From 5a0deeed5741117ee8625d6305d0034e219f102c Mon Sep 17 00:00:00 2001
From: Olivier Grenie <olivier.grenie@dibcom.fr>
Date: Tue, 3 May 2011 12:27:33 -0300
Subject: [PATCH] [media] DiBxxxx: get rid of DMA buffer on stack

This patch removes the remaining on-stack buffer for USB DMA transfer.
This patch also reduces the stack memory usage.

Cc: stable@kernel.org
Cc: Florian Mickler <florian@mickler.org>
Signed-off-by: Olivier Grenie <olivier.grenie@dibcom.fr>
Signed-off-by: Patrick Boettcher <patrick.boettcher@dibcom.fr>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
---
 drivers/media/dvb/frontends/dib0070.c        |  40 +++--
 drivers/media/dvb/frontends/dib0090.c        |  71 ++++++--
 drivers/media/dvb/frontends/dib7000m.c       |  49 ++++--
 drivers/media/dvb/frontends/dib7000p.c       |  72 +++++---
 drivers/media/dvb/frontends/dib8000.c        | 126 ++++++++++----
 drivers/media/dvb/frontends/dib9000.c        | 172 ++++++++++++-------
 drivers/media/dvb/frontends/dibx000_common.c | 109 +++++++-----
 drivers/media/dvb/frontends/dibx000_common.h |   5 +
 8 files changed, 443 insertions(+), 201 deletions(-)

diff --git a/drivers/media/dvb/frontends/dib0070.c b/drivers/media/dvb/frontends/dib0070.c
index d4e466a90e43..1d47d4da7d4c 100644
--- a/drivers/media/dvb/frontends/dib0070.c
+++ b/drivers/media/dvb/frontends/dib0070.c
@@ -73,27 +73,47 @@ struct dib0070_state {
 
     u8  wbd_gain_current;
 	u16 wbd_offset_3_3[2];
+
+	/* for the I2C transfer */
+	struct i2c_msg msg[2];
+	u8 i2c_write_buffer[3];
+	u8 i2c_read_buffer[2];
 };
 
 static uint16_t dib0070_read_reg(struct dib0070_state *state, u8 reg)
 {
-	u8 b[2];
-	struct i2c_msg msg[2] = {
-		{ .addr = state->cfg->i2c_address, .flags = 0,        .buf = &reg, .len = 1 },
-		{ .addr = state->cfg->i2c_address, .flags = I2C_M_RD, .buf = b,  .len = 2 },
-	};
-	if (i2c_transfer(state->i2c, msg, 2) != 2) {
+	state->i2c_write_buffer[0] = reg;
+
+	memset(state->msg, 0, 2 * sizeof(struct i2c_msg));
+	state->msg[0].addr = state->cfg->i2c_address;
+	state->msg[0].flags = 0;
+	state->msg[0].buf = state->i2c_write_buffer;
+	state->msg[0].len = 1;
+	state->msg[1].addr = state->cfg->i2c_address;
+	state->msg[1].flags = I2C_M_RD;
+	state->msg[1].buf = state->i2c_read_buffer;
+	state->msg[1].len = 2;
+
+	if (i2c_transfer(state->i2c, state->msg, 2) != 2) {
 		printk(KERN_WARNING "DiB0070 I2C read failed\n");
 		return 0;
 	}
-	return (b[0] << 8) | b[1];
+	return (state->i2c_read_buffer[0] << 8) | state->i2c_read_buffer[1];
 }
 
 static int dib0070_write_reg(struct dib0070_state *state, u8 reg, u16 val)
 {
-	u8 b[3] = { reg, val >> 8, val & 0xff };
-	struct i2c_msg msg = { .addr = state->cfg->i2c_address, .flags = 0, .buf = b, .len = 3 };
-	if (i2c_transfer(state->i2c, &msg, 1) != 1) {
+	state->i2c_write_buffer[0] = reg;
+	state->i2c_write_buffer[1] = val >> 8;
+	state->i2c_write_buffer[2] = val & 0xff;
+
+	memset(state->msg, 0, sizeof(struct i2c_msg));
+	state->msg[0].addr = state->cfg->i2c_address;
+	state->msg[0].flags = 0;
+	state->msg[0].buf = state->i2c_write_buffer;
+	state->msg[0].len = 3;
+
+	if (i2c_transfer(state->i2c, state->msg, 1) != 1) {
 		printk(KERN_WARNING "DiB0070 I2C write failed\n");
 		return -EREMOTEIO;
 	}
diff --git a/drivers/media/dvb/frontends/dib0090.c b/drivers/media/dvb/frontends/dib0090.c
index 52ff1a252a90..c9c935ae41e4 100644
--- a/drivers/media/dvb/frontends/dib0090.c
+++ b/drivers/media/dvb/frontends/dib0090.c
@@ -191,6 +191,11 @@ struct dib0090_state {
 	u8 wbd_calibration_gain;
 	const struct dib0090_wbd_slope *current_wbd_table;
 	u16 wbdmux;
+
+	/* for the I2C transfer */
+	struct i2c_msg msg[2];
+	u8 i2c_write_buffer[3];
+	u8 i2c_read_buffer[2];
 };
 
 struct dib0090_fw_state {
@@ -198,27 +203,48 @@ struct dib0090_fw_state {
 	struct dvb_frontend *fe;
 	struct dib0090_identity identity;
 	const struct dib0090_config *config;
+
+	/* for the I2C transfer */
+	struct i2c_msg msg;
+	u8 i2c_write_buffer[2];
+	u8 i2c_read_buffer[2];
 };
 
 static u16 dib0090_read_reg(struct dib0090_state *state, u8 reg)
 {
-	u8 b[2];
-	struct i2c_msg msg[2] = {
-		{.addr = state->config->i2c_address, .flags = 0, .buf = &reg, .len = 1},
-		{.addr = state->config->i2c_address, .flags = I2C_M_RD, .buf = b, .len = 2},
-	};
-	if (i2c_transfer(state->i2c, msg, 2) != 2) {
+	state->i2c_write_buffer[0] = reg;
+
+	memset(state->msg, 0, 2 * sizeof(struct i2c_msg));
+	state->msg[0].addr = state->config->i2c_address;
+	state->msg[0].flags = 0;
+	state->msg[0].buf = state->i2c_write_buffer;
+	state->msg[0].len = 1;
+	state->msg[1].addr = state->config->i2c_address;
+	state->msg[1].flags = I2C_M_RD;
+	state->msg[1].buf = state->i2c_read_buffer;
+	state->msg[1].len = 2;
+
+	if (i2c_transfer(state->i2c, state->msg, 2) != 2) {
 		printk(KERN_WARNING "DiB0090 I2C read failed\n");
 		return 0;
 	}
-	return (b[0] << 8) | b[1];
+
+	return (state->i2c_read_buffer[0] << 8) | state->i2c_read_buffer[1];
 }
 
 static int dib0090_write_reg(struct dib0090_state *state, u32 reg, u16 val)
 {
-	u8 b[3] = { reg & 0xff, val >> 8, val & 0xff };
-	struct i2c_msg msg = {.addr = state->config->i2c_address, .flags = 0, .buf = b, .len = 3 };
-	if (i2c_transfer(state->i2c, &msg, 1) != 1) {
+	state->i2c_write_buffer[0] = reg & 0xff;
+	state->i2c_write_buffer[1] = val >> 8;
+	state->i2c_write_buffer[2] = val & 0xff;
+
+	memset(state->msg, 0, sizeof(struct i2c_msg));
+	state->msg[0].addr = state->config->i2c_address;
+	state->msg[0].flags = 0;
+	state->msg[0].buf = state->i2c_write_buffer;
+	state->msg[0].len = 3;
+
+	if (i2c_transfer(state->i2c, state->msg, 1) != 1) {
 		printk(KERN_WARNING "DiB0090 I2C write failed\n");
 		return -EREMOTEIO;
 	}
@@ -227,20 +253,31 @@ static int dib0090_write_reg(struct dib0090_state *state, u32 reg, u16 val)
 
 static u16 dib0090_fw_read_reg(struct dib0090_fw_state *state, u8 reg)
 {
-	u8 b[2];
-	struct i2c_msg msg = {.addr = reg, .flags = I2C_M_RD, .buf = b, .len = 2 };
-	if (i2c_transfer(state->i2c, &msg, 1) != 1) {
+	state->i2c_write_buffer[0] = reg;
+
+	memset(&state->msg, 0, sizeof(struct i2c_msg));
+	state->msg.addr = reg;
+	state->msg.flags = I2C_M_RD;
+	state->msg.buf = state->i2c_read_buffer;
+	state->msg.len = 2;
+	if (i2c_transfer(state->i2c, &state->msg, 1) != 1) {
 		printk(KERN_WARNING "DiB0090 I2C read failed\n");
 		return 0;
 	}
-	return (b[0] << 8) | b[1];
+	return (state->i2c_read_buffer[0] << 8) | state->i2c_read_buffer[1];
 }
 
 static int dib0090_fw_write_reg(struct dib0090_fw_state *state, u8 reg, u16 val)
 {
-	u8 b[2] = { val >> 8, val & 0xff };
-	struct i2c_msg msg = {.addr = reg, .flags = 0, .buf = b, .len = 2 };
-	if (i2c_transfer(state->i2c, &msg, 1) != 1) {
+	state->i2c_write_buffer[0] = val >> 8;
+	state->i2c_write_buffer[1] = val & 0xff;
+
+	memset(&state->msg, 0, sizeof(struct i2c_msg));
+	state->msg.addr = reg;
+	state->msg.flags = 0;
+	state->msg.buf = state->i2c_write_buffer;
+	state->msg.len = 2;
+	if (i2c_transfer(state->i2c, &state->msg, 1) != 1) {
 		printk(KERN_WARNING "DiB0090 I2C write failed\n");
 		return -EREMOTEIO;
 	}
diff --git a/drivers/media/dvb/frontends/dib7000m.c b/drivers/media/dvb/frontends/dib7000m.c
index 289a79837f24..79cb1c20df24 100644
--- a/drivers/media/dvb/frontends/dib7000m.c
+++ b/drivers/media/dvb/frontends/dib7000m.c
@@ -50,6 +50,11 @@ struct dib7000m_state {
 	u16 revision;
 
 	u8 agc_state;
+
+	/* for the I2C transfer */
+	struct i2c_msg msg[2];
+	u8 i2c_write_buffer[4];
+	u8 i2c_read_buffer[2];
 };
 
 enum dib7000m_power_mode {
@@ -64,29 +69,39 @@ enum dib7000m_power_mode {
 
 static u16 dib7000m_read_word(struct dib7000m_state *state, u16 reg)
 {
-	u8 wb[2] = { (reg >> 8) | 0x80, reg & 0xff };
-	u8 rb[2];
-	struct i2c_msg msg[2] = {
-		{ .addr = state->i2c_addr >> 1, .flags = 0,        .buf = wb, .len = 2 },
-		{ .addr = state->i2c_addr >> 1, .flags = I2C_M_RD, .buf = rb, .len = 2 },
-	};
-
-	if (i2c_transfer(state->i2c_adap, msg, 2) != 2)
+	state->i2c_write_buffer[0] = (reg >> 8) | 0x80;
+	state->i2c_write_buffer[1] = reg & 0xff;
+
+	memset(state->msg, 0, 2 * sizeof(struct i2c_msg));
+	state->msg[0].addr = state->i2c_addr >> 1;
+	state->msg[0].flags = 0;
+	state->msg[0].buf = state->i2c_write_buffer;
+	state->msg[0].len = 2;
+	state->msg[1].addr = state->i2c_addr >> 1;
+	state->msg[1].flags = I2C_M_RD;
+	state->msg[1].buf = state->i2c_read_buffer;
+	state->msg[1].len = 2;
+
+	if (i2c_transfer(state->i2c_adap, state->msg, 2) != 2)
 		dprintk("i2c read error on %d",reg);
 
-	return (rb[0] << 8) | rb[1];
+	return (state->i2c_read_buffer[0] << 8) | state->i2c_read_buffer[1];
 }
 
 static int dib7000m_write_word(struct dib7000m_state *state, u16 reg, u16 val)
 {
-	u8 b[4] = {
-		(reg >> 8) & 0xff, reg & 0xff,
-		(val >> 8) & 0xff, val & 0xff,
-	};
-	struct i2c_msg msg = {
-		.addr = state->i2c_addr >> 1, .flags = 0, .buf = b, .len = 4
-	};
-	return i2c_transfer(state->i2c_adap, &msg, 1) != 1 ? -EREMOTEIO : 0;
+	state->i2c_write_buffer[0] = (reg >> 8) & 0xff;
+	state->i2c_write_buffer[1] = reg & 0xff;
+	state->i2c_write_buffer[2] = (val >> 8) & 0xff;
+	state->i2c_write_buffer[3] = val & 0xff;
+
+	memset(&state->msg[0], 0, sizeof(struct i2c_msg));
+	state->msg[0].addr = state->i2c_addr >> 1;
+	state->msg[0].flags = 0;
+	state->msg[0].buf = state->i2c_write_buffer;
+	state->msg[0].len = 4;
+
+	return i2c_transfer(state->i2c_adap, state->msg, 1) != 1 ? -EREMOTEIO : 0;
 }
 static void dib7000m_write_tab(struct dib7000m_state *state, u16 *buf)
 {
diff --git a/drivers/media/dvb/frontends/dib7000p.c b/drivers/media/dvb/frontends/dib7000p.c
index 900af60b9d36..0c9f40c2a251 100644
--- a/drivers/media/dvb/frontends/dib7000p.c
+++ b/drivers/media/dvb/frontends/dib7000p.c
@@ -63,6 +63,11 @@ struct dib7000p_state {
 
 	u16 tuner_enable;
 	struct i2c_adapter dib7090_tuner_adap;
+
+	/* for the I2C transfer */
+	struct i2c_msg msg[2];
+	u8 i2c_write_buffer[4];
+	u8 i2c_read_buffer[2];
 };
 
 enum dib7000p_power_mode {
@@ -76,29 +81,39 @@ static int dib7090_set_diversity_in(struct dvb_frontend *fe, int onoff);
 
 static u16 dib7000p_read_word(struct dib7000p_state *state, u16 reg)
 {
-	u8 wb[2] = { reg >> 8, reg & 0xff };
-	u8 rb[2];
-	struct i2c_msg msg[2] = {
-		{.addr = state->i2c_addr >> 1, .flags = 0, .buf = wb, .len = 2},
-		{.addr = state->i2c_addr >> 1, .flags = I2C_M_RD, .buf = rb, .len = 2},
-	};
+	state->i2c_write_buffer[0] = reg >> 8;
+	state->i2c_write_buffer[1] = reg & 0xff;
+
+	memset(state->msg, 0, 2 * sizeof(struct i2c_msg));
+	state->msg[0].addr = state->i2c_addr >> 1;
+	state->msg[0].flags = 0;
+	state->msg[0].buf = state->i2c_write_buffer;
+	state->msg[0].len = 2;
+	state->msg[1].addr = state->i2c_addr >> 1;
+	state->msg[1].flags = I2C_M_RD;
+	state->msg[1].buf = state->i2c_read_buffer;
+	state->msg[1].len = 2;
 
-	if (i2c_transfer(state->i2c_adap, msg, 2) != 2)
+	if (i2c_transfer(state->i2c_adap, state->msg, 2) != 2)
 		dprintk("i2c read error on %d", reg);
 
-	return (rb[0] << 8) | rb[1];
+	return (state->i2c_read_buffer[0] << 8) | state->i2c_read_buffer[1];
 }
 
 static int dib7000p_write_word(struct dib7000p_state *state, u16 reg, u16 val)
 {
-	u8 b[4] = {
-		(reg >> 8) & 0xff, reg & 0xff,
-		(val >> 8) & 0xff, val & 0xff,
-	};
-	struct i2c_msg msg = {
-		.addr = state->i2c_addr >> 1, .flags = 0, .buf = b, .len = 4
-	};
-	return i2c_transfer(state->i2c_adap, &msg, 1) != 1 ? -EREMOTEIO : 0;
+	state->i2c_write_buffer[0] = (reg >> 8) & 0xff;
+	state->i2c_write_buffer[1] = reg & 0xff;
+	state->i2c_write_buffer[2] = (val >> 8) & 0xff;
+	state->i2c_write_buffer[3] = val & 0xff;
+
+	memset(&state->msg[0], 0, sizeof(struct i2c_msg));
+	state->msg[0].addr = state->i2c_addr >> 1;
+	state->msg[0].flags = 0;
+	state->msg[0].buf = state->i2c_write_buffer;
+	state->msg[0].len = 4;
+
+	return i2c_transfer(state->i2c_adap, state->msg, 1) != 1 ? -EREMOTEIO : 0;
 }
 
 static void dib7000p_write_tab(struct dib7000p_state *state, u16 * buf)
@@ -1550,11 +1565,24 @@ static void dib7000p_release(struct dvb_frontend *demod)
 
 int dib7000pc_detection(struct i2c_adapter *i2c_adap)
 {
-	u8 tx[2], rx[2];
+	u8 *tx, *rx;
 	struct i2c_msg msg[2] = {
-		{.addr = 18 >> 1, .flags = 0, .buf = tx, .len = 2},
-		{.addr = 18 >> 1, .flags = I2C_M_RD, .buf = rx, .len = 2},
+		{.addr = 18 >> 1, .flags = 0, .len = 2},
+		{.addr = 18 >> 1, .flags = I2C_M_RD, .len = 2},
 	};
+	int ret = 0;
+
+	tx = kzalloc(2*sizeof(u8), GFP_KERNEL);
+	if (!tx)
+		return -ENOMEM;
+	rx = kzalloc(2*sizeof(u8), GFP_KERNEL);
+	if (!rx) {
+		goto rx_memory_error;
+		ret = -ENOMEM;
+	}
+
+	msg[0].buf = tx;
+	msg[1].buf = rx;
 
 	tx[0] = 0x03;
 	tx[1] = 0x00;
@@ -1574,7 +1602,11 @@ int dib7000pc_detection(struct i2c_adapter *i2c_adap)
 		}
 
 	dprintk("-D-  DiB7000PC not detected");
-	return 0;
+
+	kfree(rx);
+rx_memory_error:
+	kfree(tx);
+	return ret;
 }
 EXPORT_SYMBOL(dib7000pc_detection);
 
diff --git a/drivers/media/dvb/frontends/dib8000.c b/drivers/media/dvb/frontends/dib8000.c
index c1c3e26906e2..7d2ea112ae2b 100644
--- a/drivers/media/dvb/frontends/dib8000.c
+++ b/drivers/media/dvb/frontends/dib8000.c
@@ -35,6 +35,8 @@ MODULE_PARM_DESC(debug, "turn on debugging (default: 0)");
 struct i2c_device {
 	struct i2c_adapter *adap;
 	u8 addr;
+	u8 *i2c_write_buffer;
+	u8 *i2c_read_buffer;
 };
 
 struct dib8000_state {
@@ -70,6 +72,11 @@ struct dib8000_state {
 	u32 status;
 
 	struct dvb_frontend *fe[MAX_NUMBER_OF_FRONTENDS];
+
+	/* for the I2C transfer */
+	struct i2c_msg msg[2];
+	u8 i2c_write_buffer[4];
+	u8 i2c_read_buffer[2];
 };
 
 enum dib8000_power_mode {
@@ -79,22 +86,41 @@ enum dib8000_power_mode {
 
 static u16 dib8000_i2c_read16(struct i2c_device *i2c, u16 reg)
 {
-	u8 wb[2] = { reg >> 8, reg & 0xff };
-	u8 rb[2];
 	struct i2c_msg msg[2] = {
-		{.addr = i2c->addr >> 1,.flags = 0,.buf = wb,.len = 2},
-		{.addr = i2c->addr >> 1,.flags = I2C_M_RD,.buf = rb,.len = 2},
+		{.addr = i2c->addr >> 1, .flags = 0,
+			.buf = i2c->i2c_write_buffer, .len = 2},
+		{.addr = i2c->addr >> 1, .flags = I2C_M_RD,
+			.buf = i2c->i2c_read_buffer, .len = 2},
 	};
 
+	msg[0].buf[0] = reg >> 8;
+	msg[0].buf[1] = reg & 0xff;
+
 	if (i2c_transfer(i2c->adap, msg, 2) != 2)
 		dprintk("i2c read error on %d", reg);
 
-	return (rb[0] << 8) | rb[1];
+	return (msg[1].buf[0] << 8) | msg[1].buf[1];
 }
 
 static u16 dib8000_read_word(struct dib8000_state *state, u16 reg)
 {
-	return dib8000_i2c_read16(&state->i2c, reg);
+	state->i2c_write_buffer[0] = reg >> 8;
+	state->i2c_write_buffer[1] = reg & 0xff;
+
+	memset(state->msg, 0, 2 * sizeof(struct i2c_msg));
+	state->msg[0].addr = state->i2c.addr >> 1;
+	state->msg[0].flags = 0;
+	state->msg[0].buf = state->i2c_write_buffer;
+	state->msg[0].len = 2;
+	state->msg[1].addr = state->i2c.addr >> 1;
+	state->msg[1].flags = I2C_M_RD;
+	state->msg[1].buf = state->i2c_read_buffer;
+	state->msg[1].len = 2;
+
+	if (i2c_transfer(state->i2c.adap, state->msg, 2) != 2)
+		dprintk("i2c read error on %d", reg);
+
+	return (state->i2c_read_buffer[0] << 8) | state->i2c_read_buffer[1];
 }
 
 static u32 dib8000_read32(struct dib8000_state *state, u16 reg)
@@ -109,19 +135,34 @@ static u32 dib8000_read32(struct dib8000_state *state, u16 reg)
 
 static int dib8000_i2c_write16(struct i2c_device *i2c, u16 reg, u16 val)
 {
-	u8 b[4] = {
-		(reg >> 8) & 0xff, reg & 0xff,
-		(val >> 8) & 0xff, val & 0xff,
-	};
-	struct i2c_msg msg = {
-		.addr = i2c->addr >> 1,.flags = 0,.buf = b,.len = 4
-	};
-	return i2c_transfer(i2c->adap, &msg, 1) != 1 ? -EREMOTEIO : 0;
+	struct i2c_msg msg = {.addr = i2c->addr >> 1, .flags = 0,
+		.buf = i2c->i2c_write_buffer, .len = 4};
+	int ret = 0;
+
+	msg.buf[0] = (reg >> 8) & 0xff;
+	msg.buf[1] = reg & 0xff;
+	msg.buf[2] = (val >> 8) & 0xff;
+	msg.buf[3] = val & 0xff;
+
+	ret = i2c_transfer(i2c->adap, &msg, 1) != 1 ? -EREMOTEIO : 0;
+
+	return ret;
 }
 
 static int dib8000_write_word(struct dib8000_state *state, u16 reg, u16 val)
 {
-	return dib8000_i2c_write16(&state->i2c, reg, val);
+	state->i2c_write_buffer[0] = (reg >> 8) & 0xff;
+	state->i2c_write_buffer[1] = reg & 0xff;
+	state->i2c_write_buffer[2] = (val >> 8) & 0xff;
+	state->i2c_write_buffer[3] = val & 0xff;
+
+	memset(&state->msg[0], 0, sizeof(struct i2c_msg));
+	state->msg[0].addr = state->i2c.addr >> 1;
+	state->msg[0].flags = 0;
+	state->msg[0].buf = state->i2c_write_buffer;
+	state->msg[0].len = 4;
+
+	return i2c_transfer(state->i2c.adap, state->msg, 1) != 1 ? -EREMOTEIO : 0;
 }
 
 static const s16 coeff_2k_sb_1seg_dqpsk[8] = {
@@ -980,30 +1021,31 @@ static void dib8000_update_timf(struct dib8000_state *state)
 	dprintk("Updated timing frequency: %d (default: %d)", state->timf, state->timf_default);
 }
 
+static const u16 adc_target_16dB[11] = {
+	(1 << 13) - 825 - 117,
+	(1 << 13) - 837 - 117,
+	(1 << 13) - 811 - 117,
+	(1 << 13) - 766 - 117,
+	(1 << 13) - 737 - 117,
+	(1 << 13) - 693 - 117,
+	(1 << 13) - 648 - 117,
+	(1 << 13) - 619 - 117,
+	(1 << 13) - 575 - 117,
+	(1 << 13) - 531 - 117,
+	(1 << 13) - 501 - 117
+};
+static const u8 permu_seg[] = { 6, 5, 7, 4, 8, 3, 9, 2, 10, 1, 11, 0, 12 };
+
 static void dib8000_set_channel(struct dib8000_state *state, u8 seq, u8 autosearching)
 {
 	u16 mode, max_constellation, seg_diff_mask = 0, nbseg_diff = 0;
 	u8 guard, crate, constellation, timeI;
-	u8 permu_seg[] = { 6, 5, 7, 4, 8, 3, 9, 2, 10, 1, 11, 0, 12 };
 	u16 i, coeff[4], P_cfr_left_edge = 0, P_cfr_right_edge = 0, seg_mask13 = 0x1fff;	// All 13 segments enabled
 	const s16 *ncoeff = NULL, *ana_fe;
 	u16 tmcc_pow = 0;
 	u16 coff_pow = 0x2800;
 	u16 init_prbs = 0xfff;
 	u16 ana_gain = 0;
-	u16 adc_target_16dB[11] = {
-		(1 << 13) - 825 - 117,
-		(1 << 13) - 837 - 117,
-		(1 << 13) - 811 - 117,
-		(1 << 13) - 766 - 117,
-		(1 << 13) - 737 - 117,
-		(1 << 13) - 693 - 117,
-		(1 << 13) - 648 - 117,
-		(1 << 13) - 619 - 117,
-		(1 << 13) - 575 - 117,
-		(1 << 13) - 531 - 117,
-		(1 << 13) - 501 - 117
-	};
 
 	if (state->ber_monitored_layer != LAYER_ALL)
 		dib8000_write_word(state, 285, (dib8000_read_word(state, 285) & 0x60) | state->ber_monitored_layer);
@@ -2379,10 +2421,22 @@ EXPORT_SYMBOL(dib8000_get_slave_frontend);
 
 int dib8000_i2c_enumeration(struct i2c_adapter *host, int no_of_demods, u8 default_addr, u8 first_addr)
 {
-	int k = 0;
+	int k = 0, ret = 0;
 	u8 new_addr = 0;
 	struct i2c_device client = {.adap = host };
 
+	client.i2c_write_buffer = kzalloc(4 * sizeof(u8), GFP_KERNEL);
+	if (!client.i2c_write_buffer) {
+		dprintk("%s: not enough memory", __func__);
+		return -ENOMEM;
+	}
+	client.i2c_read_buffer = kzalloc(4 * sizeof(u8), GFP_KERNEL);
+	if (!client.i2c_read_buffer) {
+		dprintk("%s: not enough memory", __func__);
+		ret = -ENOMEM;
+		goto error_memory;
+	}
+
 	for (k = no_of_demods - 1; k >= 0; k--) {
 		/* designated i2c address */
 		new_addr = first_addr + (k << 1);
@@ -2394,7 +2448,8 @@ int dib8000_i2c_enumeration(struct i2c_adapter *host, int no_of_demods, u8 defau
 			client.addr = default_addr;
 			if (dib8000_identify(&client) == 0) {
 				dprintk("#%d: not identified", k);
-				return -EINVAL;
+				ret  = -EINVAL;
+				goto error;
 			}
 		}
 
@@ -2420,7 +2475,12 @@ int dib8000_i2c_enumeration(struct i2c_adapter *host, int no_of_demods, u8 defau
 		dib8000_i2c_write16(&client, 1286, 0);
 	}
 
-	return 0;
+error:
+	kfree(client.i2c_read_buffer);
+error_memory:
+	kfree(client.i2c_write_buffer);
+
+	return ret;
 }
 
 EXPORT_SYMBOL(dib8000_i2c_enumeration);
@@ -2519,6 +2579,8 @@ struct dvb_frontend *dib8000_attach(struct i2c_adapter *i2c_adap, u8 i2c_addr, s
 	memcpy(&state->cfg, cfg, sizeof(struct dib8000_config));
 	state->i2c.adap = i2c_adap;
 	state->i2c.addr = i2c_addr;
+	state->i2c.i2c_write_buffer = state->i2c_write_buffer;
+	state->i2c.i2c_read_buffer = state->i2c_read_buffer;
 	state->gpio_val = cfg->gpio_val;
 	state->gpio_dir = cfg->gpio_dir;
 
diff --git a/drivers/media/dvb/frontends/dib9000.c b/drivers/media/dvb/frontends/dib9000.c
index b25ef2bb5078..a0855883b5ce 100644
--- a/drivers/media/dvb/frontends/dib9000.c
+++ b/drivers/media/dvb/frontends/dib9000.c
@@ -27,6 +27,8 @@ MODULE_PARM_DESC(debug, "turn on debugging (default: 0)");
 struct i2c_device {
 	struct i2c_adapter *i2c_adap;
 	u8 i2c_addr;
+	u8 *i2c_read_buffer;
+	u8 *i2c_write_buffer;
 };
 
 /* lock */
@@ -92,11 +94,16 @@ struct dib9000_state {
 
 	struct dvb_frontend *fe[MAX_NUMBER_OF_FRONTENDS];
 	u16 component_bus_speed;
+
+	/* for the I2C transfer */
+	struct i2c_msg msg[2];
+	u8 i2c_write_buffer[255];
+	u8 i2c_read_buffer[255];
 };
 
-u32 fe_info[44] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
+static const u32 fe_info[44] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
 	0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
-	0, 0, 0
+	0, 0, 0, 0, 0, 0, 0, 0
 };
 
 enum dib9000_power_mode {
@@ -217,25 +224,33 @@ static u16 dib9000_read16_attr(struct dib9000_state *state, u16 reg, u8 * b, u32
 	u32 chunk_size = 126;
 	u32 l;
 	int ret;
-	u8 wb[2] = { reg >> 8, reg & 0xff };
-	struct i2c_msg msg[2] = {
-		{.addr = state->i2c.i2c_addr >> 1, .flags = 0, .buf = wb, .len = 2},
-		{.addr = state->i2c.i2c_addr >> 1, .flags = I2C_M_RD, .buf = b, .len = len},
-	};
 
 	if (state->platform.risc.fw_is_running && (reg < 1024))
 		return dib9000_risc_apb_access_read(state, reg, attribute, NULL, 0, b, len);
 
+	memset(state->msg, 0, 2 * sizeof(struct i2c_msg));
+	state->msg[0].addr = state->i2c.i2c_addr >> 1;
+	state->msg[0].flags = 0;
+	state->msg[0].buf = state->i2c_write_buffer;
+	state->msg[0].len = 2;
+	state->msg[1].addr = state->i2c.i2c_addr >> 1;
+	state->msg[1].flags = I2C_M_RD;
+	state->msg[1].buf = b;
+	state->msg[1].len = len;
+
+	state->i2c_write_buffer[0] = reg >> 8;
+	state->i2c_write_buffer[1] = reg & 0xff;
+
 	if (attribute & DATA_BUS_ACCESS_MODE_8BIT)
-		wb[0] |= (1 << 5);
+		state->i2c_write_buffer[0] |= (1 << 5);
 	if (attribute & DATA_BUS_ACCESS_MODE_NO_ADDRESS_INCREMENT)
-		wb[0] |= (1 << 4);
+		state->i2c_write_buffer[0] |= (1 << 4);
 
 	do {
 		l = len < chunk_size ? len : chunk_size;
-		msg[1].len = l;
-		msg[1].buf = b;
-		ret = i2c_transfer(state->i2c.i2c_adap, msg, 2) != 2 ? -EREMOTEIO : 0;
+		state->msg[1].len = l;
+		state->msg[1].buf = b;
+		ret = i2c_transfer(state->i2c.i2c_adap, state->msg, 2) != 2 ? -EREMOTEIO : 0;
 		if (ret != 0) {
 			dprintk("i2c read error on %d", reg);
 			return -EREMOTEIO;
@@ -253,50 +268,47 @@ static u16 dib9000_read16_attr(struct dib9000_state *state, u16 reg, u8 * b, u32
 
 static u16 dib9000_i2c_read16(struct i2c_device *i2c, u16 reg)
 {
-	u8 b[2];
-	u8 wb[2] = { reg >> 8, reg & 0xff };
 	struct i2c_msg msg[2] = {
-		{.addr = i2c->i2c_addr >> 1, .flags = 0, .buf = wb, .len = 2},
-		{.addr = i2c->i2c_addr >> 1, .flags = I2C_M_RD, .buf = b, .len = 2},
+		{.addr = i2c->i2c_addr >> 1, .flags = 0,
+			.buf = i2c->i2c_write_buffer, .len = 2},
+		{.addr = i2c->i2c_addr >> 1, .flags = I2C_M_RD,
+			.buf = i2c->i2c_read_buffer, .len = 2},
 	};
 
+	i2c->i2c_write_buffer[0] = reg >> 8;
+	i2c->i2c_write_buffer[1] = reg & 0xff;
+
 	if (i2c_transfer(i2c->i2c_adap, msg, 2) != 2) {
 		dprintk("read register %x error", reg);
 		return 0;
 	}
 
-	return (b[0] << 8) | b[1];
+	return (i2c->i2c_read_buffer[0] << 8) | i2c->i2c_read_buffer[1];
 }
 
 static inline u16 dib9000_read_word(struct dib9000_state *state, u16 reg)
 {
-	u8 b[2];
-	if (dib9000_read16_attr(state, reg, b, 2, 0) != 0)
+	if (dib9000_read16_attr(state, reg, state->i2c_read_buffer, 2, 0) != 0)
 		return 0;
-	return (b[0] << 8 | b[1]);
+	return (state->i2c_read_buffer[0] << 8) | state->i2c_read_buffer[1];
 }
 
 static inline u16 dib9000_read_word_attr(struct dib9000_state *state, u16 reg, u16 attribute)
 {
-	u8 b[2];
-	if (dib9000_read16_attr(state, reg, b, 2, attribute) != 0)
+	if (dib9000_read16_attr(state, reg, state->i2c_read_buffer, 2,
+				attribute) != 0)
 		return 0;
-	return (b[0] << 8 | b[1]);
+	return (state->i2c_read_buffer[0] << 8) | state->i2c_read_buffer[1];
 }
 
 #define dib9000_read16_noinc_attr(state, reg, b, len, attribute) dib9000_read16_attr(state, reg, b, len, (attribute) | DATA_BUS_ACCESS_MODE_NO_ADDRESS_INCREMENT)
 
 static u16 dib9000_write16_attr(struct dib9000_state *state, u16 reg, const u8 * buf, u32 len, u16 attribute)
 {
-	u8 b[255];
 	u32 chunk_size = 126;
 	u32 l;
 	int ret;
 
-	struct i2c_msg msg = {
-		.addr = state->i2c.i2c_addr >> 1, .flags = 0, .buf = b, .len = len + 2
-	};
-
 	if (state->platform.risc.fw_is_running && (reg < 1024)) {
 		if (dib9000_risc_apb_access_write
 		    (state, reg, DATA_BUS_ACCESS_MODE_16BIT | DATA_BUS_ACCESS_MODE_NO_ADDRESS_INCREMENT | attribute, buf, len) != 0)
@@ -304,20 +316,26 @@ static u16 dib9000_write16_attr(struct dib9000_state *state, u16 reg, const u8 *
 		return 0;
 	}
 
-	b[0] = (reg >> 8) & 0xff;
-	b[1] = (reg) & 0xff;
+	memset(&state->msg[0], 0, sizeof(struct i2c_msg));
+	state->msg[0].addr = state->i2c.i2c_addr >> 1;
+	state->msg[0].flags = 0;
+	state->msg[0].buf = state->i2c_write_buffer;
+	state->msg[0].len = len + 2;
+
+	state->i2c_write_buffer[0] = (reg >> 8) & 0xff;
+	state->i2c_write_buffer[1] = (reg) & 0xff;
 
 	if (attribute & DATA_BUS_ACCESS_MODE_8BIT)
-		b[0] |= (1 << 5);
+		state->i2c_write_buffer[0] |= (1 << 5);
 	if (attribute & DATA_BUS_ACCESS_MODE_NO_ADDRESS_INCREMENT)
-		b[0] |= (1 << 4);
+		state->i2c_write_buffer[0] |= (1 << 4);
 
 	do {
 		l = len < chunk_size ? len : chunk_size;
-		msg.len = l + 2;
-		memcpy(&b[2], buf, l);
+		state->msg[0].len = l + 2;
+		memcpy(&state->i2c_write_buffer[2], buf, l);
 
-		ret = i2c_transfer(state->i2c.i2c_adap, &msg, 1) != 1 ? -EREMOTEIO : 0;
+		ret = i2c_transfer(state->i2c.i2c_adap, state->msg, 1) != 1 ? -EREMOTEIO : 0;
 
 		buf += l;
 		len -= l;
@@ -331,11 +349,16 @@ static u16 dib9000_write16_attr(struct dib9000_state *state, u16 reg, const u8 *
 
 static int dib9000_i2c_write16(struct i2c_device *i2c, u16 reg, u16 val)
 {
-	u8 b[4] = { (reg >> 8) & 0xff, reg & 0xff, (val >> 8) & 0xff, val & 0xff };
 	struct i2c_msg msg = {
-		.addr = i2c->i2c_addr >> 1, .flags = 0, .buf = b, .len = 4
+		.addr = i2c->i2c_addr >> 1, .flags = 0,
+		.buf = i2c->i2c_write_buffer, .len = 4
 	};
 
+	i2c->i2c_write_buffer[0] = (reg >> 8) & 0xff;
+	i2c->i2c_write_buffer[1] = reg & 0xff;
+	i2c->i2c_write_buffer[2] = (val >> 8) & 0xff;
+	i2c->i2c_write_buffer[3] = val & 0xff;
+
 	return i2c_transfer(i2c->i2c_adap, &msg, 1) != 1 ? -EREMOTEIO : 0;
 }
 
@@ -1015,8 +1038,8 @@ static int dib9000_fw_memmbx_sync(struct dib9000_state *state, u8 i)
 		return 0;
 	dib9000_risc_mem_write(state, FE_MM_RW_SYNC, &i);
 	do {
-		dib9000_risc_mem_read(state, FE_MM_RW_SYNC, &i, 1);
-	} while (i && index_loop--);
+		dib9000_risc_mem_read(state, FE_MM_RW_SYNC, state->i2c_read_buffer, 1);
+	} while (state->i2c_read_buffer[0] && index_loop--);
 
 	if (index_loop > 0)
 		return 0;
@@ -1139,7 +1162,7 @@ static int dib9000_fw_get_channel(struct dvb_frontend *fe, struct dvb_frontend_p
 
 		s8 intlv_native;
 	};
-	struct dibDVBTChannel ch;
+	struct dibDVBTChannel *ch;
 	int ret = 0;
 
 	DibAcquireLock(&state->platform.risc.mem_mbx_lock);
@@ -1148,9 +1171,12 @@ static int dib9000_fw_get_channel(struct dvb_frontend *fe, struct dvb_frontend_p
 		ret = -EIO;
 	}
 
-	dib9000_risc_mem_read(state, FE_MM_R_CHANNEL_UNION, (u8 *) &ch, sizeof(struct dibDVBTChannel));
+	dib9000_risc_mem_read(state, FE_MM_R_CHANNEL_UNION,
+			state->i2c_read_buffer, sizeof(struct dibDVBTChannel));
+	ch = (struct dibDVBTChannel *)state->i2c_read_buffer;
+
 
-	switch (ch.spectrum_inversion & 0x7) {
+	switch (ch->spectrum_inversion & 0x7) {
 	case 1:
 		state->fe[0]->dtv_property_cache.inversion = INVERSION_ON;
 		break;
@@ -1162,7 +1188,7 @@ static int dib9000_fw_get_channel(struct dvb_frontend *fe, struct dvb_frontend_p
 		state->fe[0]->dtv_property_cache.inversion = INVERSION_AUTO;
 		break;
 	}
-	switch (ch.nfft) {
+	switch (ch->nfft) {
 	case 0:
 		state->fe[0]->dtv_property_cache.transmission_mode = TRANSMISSION_MODE_2K;
 		break;
@@ -1177,7 +1203,7 @@ static int dib9000_fw_get_channel(struct dvb_frontend *fe, struct dvb_frontend_p
 		state->fe[0]->dtv_property_cache.transmission_mode = TRANSMISSION_MODE_AUTO;
 		break;
 	}
-	switch (ch.guard) {
+	switch (ch->guard) {
 	case 0:
 		state->fe[0]->dtv_property_cache.guard_interval = GUARD_INTERVAL_1_32;
 		break;
@@ -1195,7 +1221,7 @@ static int dib9000_fw_get_channel(struct dvb_frontend *fe, struct dvb_frontend_p
 		state->fe[0]->dtv_property_cache.guard_interval = GUARD_INTERVAL_AUTO;
 		break;
 	}
-	switch (ch.constellation) {
+	switch (ch->constellation) {
 	case 2:
 		state->fe[0]->dtv_property_cache.modulation = QAM_64;
 		break;
@@ -1210,7 +1236,7 @@ static int dib9000_fw_get_channel(struct dvb_frontend *fe, struct dvb_frontend_p
 		state->fe[0]->dtv_property_cache.modulation = QAM_AUTO;
 		break;
 	}
-	switch (ch.hrch) {
+	switch (ch->hrch) {
 	case 0:
 		state->fe[0]->dtv_property_cache.hierarchy = HIERARCHY_NONE;
 		break;
@@ -1222,7 +1248,7 @@ static int dib9000_fw_get_channel(struct dvb_frontend *fe, struct dvb_frontend_p
 		state->fe[0]->dtv_property_cache.hierarchy = HIERARCHY_AUTO;
 		break;
 	}
-	switch (ch.code_rate_hp) {
+	switch (ch->code_rate_hp) {
 	case 1:
 		state->fe[0]->dtv_property_cache.code_rate_HP = FEC_1_2;
 		break;
@@ -1243,7 +1269,7 @@ static int dib9000_fw_get_channel(struct dvb_frontend *fe, struct dvb_frontend_p
 		state->fe[0]->dtv_property_cache.code_rate_HP = FEC_AUTO;
 		break;
 	}
-	switch (ch.code_rate_lp) {
+	switch (ch->code_rate_lp) {
 	case 1:
 		state->fe[0]->dtv_property_cache.code_rate_LP = FEC_1_2;
 		break;
@@ -1439,9 +1465,10 @@ static int dib9000_fw_tune(struct dvb_frontend *fe, struct dvb_frontend_paramete
 		break;
 	case CT_DEMOD_STEP_1:
 		if (search)
-			dib9000_risc_mem_read(state, FE_MM_R_CHANNEL_SEARCH_STATE, (u8 *) &i, 1);
+			dib9000_risc_mem_read(state, FE_MM_R_CHANNEL_SEARCH_STATE, state->i2c_read_buffer, 1);
 		else
-			dib9000_risc_mem_read(state, FE_MM_R_CHANNEL_TUNE_STATE, (u8 *) &i, 1);
+			dib9000_risc_mem_read(state, FE_MM_R_CHANNEL_TUNE_STATE, state->i2c_read_buffer, 1);
+		i = (s8)state->i2c_read_buffer[0];
 		switch (i) {	/* something happened */
 		case 0:
 			break;
@@ -2038,14 +2065,17 @@ static int dib9000_read_status(struct dvb_frontend *fe, fe_status_t * stat)
 static int dib9000_read_ber(struct dvb_frontend *fe, u32 * ber)
 {
 	struct dib9000_state *state = fe->demodulator_priv;
-	u16 c[16];
+	u16 *c;
 
 	DibAcquireLock(&state->platform.risc.mem_mbx_lock);
 	if (dib9000_fw_memmbx_sync(state, FE_SYNC_CHANNEL) < 0)
 		return -EIO;
-	dib9000_risc_mem_read(state, FE_MM_R_FE_MONITOR, (u8 *) c, sizeof(c));
+	dib9000_risc_mem_read(state, FE_MM_R_FE_MONITOR,
+			state->i2c_read_buffer, 16 * 2);
 	DibReleaseLock(&state->platform.risc.mem_mbx_lock);
 
+	c = (u16 *)state->i2c_read_buffer;
+
 	*ber = c[10] << 16 | c[11];
 	return 0;
 }
@@ -2054,7 +2084,7 @@ static int dib9000_read_signal_strength(struct dvb_frontend *fe, u16 * strength)
 {
 	struct dib9000_state *state = fe->demodulator_priv;
 	u8 index_frontend;
-	u16 c[16];
+	u16 *c = (u16 *)state->i2c_read_buffer;
 	u16 val;
 
 	*strength = 0;
@@ -2069,7 +2099,7 @@ static int dib9000_read_signal_strength(struct dvb_frontend *fe, u16 * strength)
 	DibAcquireLock(&state->platform.risc.mem_mbx_lock);
 	if (dib9000_fw_memmbx_sync(state, FE_SYNC_CHANNEL) < 0)
 		return -EIO;
-	dib9000_risc_mem_read(state, FE_MM_R_FE_MONITOR, (u8 *) c, sizeof(c));
+	dib9000_risc_mem_read(state, FE_MM_R_FE_MONITOR, (u8 *) c, 16 * 2);
 	DibReleaseLock(&state->platform.risc.mem_mbx_lock);
 
 	val = 65535 - c[4];
@@ -2083,14 +2113,14 @@ static int dib9000_read_signal_strength(struct dvb_frontend *fe, u16 * strength)
 static u32 dib9000_get_snr(struct dvb_frontend *fe)
 {
 	struct dib9000_state *state = fe->demodulator_priv;
-	u16 c[16];
+	u16 *c = (u16 *)state->i2c_read_buffer;
 	u32 n, s, exp;
 	u16 val;
 
 	DibAcquireLock(&state->platform.risc.mem_mbx_lock);
 	if (dib9000_fw_memmbx_sync(state, FE_SYNC_CHANNEL) < 0)
 		return -EIO;
-	dib9000_risc_mem_read(state, FE_MM_R_FE_MONITOR, (u8 *) c, sizeof(c));
+	dib9000_risc_mem_read(state, FE_MM_R_FE_MONITOR, (u8 *) c, 16 * 2);
 	DibReleaseLock(&state->platform.risc.mem_mbx_lock);
 
 	val = c[7];
@@ -2137,12 +2167,12 @@ static int dib9000_read_snr(struct dvb_frontend *fe, u16 * snr)
 static int dib9000_read_unc_blocks(struct dvb_frontend *fe, u32 * unc)
 {
 	struct dib9000_state *state = fe->demodulator_priv;
-	u16 c[16];
+	u16 *c = (u16 *)state->i2c_read_buffer;
 
 	DibAcquireLock(&state->platform.risc.mem_mbx_lock);
 	if (dib9000_fw_memmbx_sync(state, FE_SYNC_CHANNEL) < 0)
 		return -EIO;
-	dib9000_risc_mem_read(state, FE_MM_R_FE_MONITOR, (u8 *) c, sizeof(c));
+	dib9000_risc_mem_read(state, FE_MM_R_FE_MONITOR, (u8 *) c, 16 * 2);
 	DibReleaseLock(&state->platform.risc.mem_mbx_lock);
 
 	*unc = c[12];
@@ -2151,10 +2181,22 @@ static int dib9000_read_unc_blocks(struct dvb_frontend *fe, u32 * unc)
 
 int dib9000_i2c_enumeration(struct i2c_adapter *i2c, int no_of_demods, u8 default_addr, u8 first_addr)
 {
-	int k = 0;
+	int k = 0, ret = 0;
 	u8 new_addr = 0;
 	struct i2c_device client = {.i2c_adap = i2c };
 
+	client.i2c_write_buffer = kzalloc(4 * sizeof(u8), GFP_KERNEL);
+	if (!client.i2c_write_buffer) {
+		dprintk("%s: not enough memory", __func__);
+		return -ENOMEM;
+	}
+	client.i2c_read_buffer = kzalloc(4 * sizeof(u8), GFP_KERNEL);
+	if (!client.i2c_read_buffer) {
+		dprintk("%s: not enough memory", __func__);
+		ret = -ENOMEM;
+		goto error_memory;
+	}
+
 	client.i2c_addr = default_addr + 16;
 	dib9000_i2c_write16(&client, 1796, 0x0);
 
@@ -2178,7 +2220,8 @@ int dib9000_i2c_enumeration(struct i2c_adapter *i2c, int no_of_demods, u8 defaul
 			client.i2c_addr = default_addr;
 			if (dib9000_identify(&client) == 0) {
 				dprintk("DiB9000 #%d: not identified", k);
-				return -EIO;
+				ret = -EIO;
+				goto error;
 			}
 		}
 
@@ -2196,7 +2239,12 @@ int dib9000_i2c_enumeration(struct i2c_adapter *i2c, int no_of_demods, u8 defaul
 		dib9000_i2c_write16(&client, 1795, 0);
 	}
 
-	return 0;
+error:
+	kfree(client.i2c_read_buffer);
+error_memory:
+	kfree(client.i2c_write_buffer);
+
+	return ret;
 }
 EXPORT_SYMBOL(dib9000_i2c_enumeration);
 
@@ -2263,6 +2311,8 @@ struct dvb_frontend *dib9000_attach(struct i2c_adapter *i2c_adap, u8 i2c_addr, c
 	memcpy(&st->chip.d9.cfg, cfg, sizeof(struct dib9000_config));
 	st->i2c.i2c_adap = i2c_adap;
 	st->i2c.i2c_addr = i2c_addr;
+	st->i2c.i2c_write_buffer = st->i2c_write_buffer;
+	st->i2c.i2c_read_buffer = st->i2c_read_buffer;
 
 	st->gpio_dir = DIB9000_GPIO_DEFAULT_DIRECTIONS;
 	st->gpio_val = DIB9000_GPIO_DEFAULT_VALUES;
diff --git a/drivers/media/dvb/frontends/dibx000_common.c b/drivers/media/dvb/frontends/dibx000_common.c
index f6938f97feb4..dc5d17a67579 100644
--- a/drivers/media/dvb/frontends/dibx000_common.c
+++ b/drivers/media/dvb/frontends/dibx000_common.c
@@ -10,30 +10,39 @@ MODULE_PARM_DESC(debug, "turn on debugging (default: 0)");
 
 static int dibx000_write_word(struct dibx000_i2c_master *mst, u16 reg, u16 val)
 {
-	u8 b[4] = {
-		(reg >> 8) & 0xff, reg & 0xff,
-		(val >> 8) & 0xff, val & 0xff,
-	};
-	struct i2c_msg msg = {
-		.addr = mst->i2c_addr,.flags = 0,.buf = b,.len = 4
-	};
-
-	return i2c_transfer(mst->i2c_adap, &msg, 1) != 1 ? -EREMOTEIO : 0;
+	mst->i2c_write_buffer[0] = (reg >> 8) & 0xff;
+	mst->i2c_write_buffer[1] = reg & 0xff;
+	mst->i2c_write_buffer[2] = (val >> 8) & 0xff;
+	mst->i2c_write_buffer[3] = val & 0xff;
+
+	memset(mst->msg, 0, sizeof(struct i2c_msg));
+	mst->msg[0].addr = mst->i2c_addr;
+	mst->msg[0].flags = 0;
+	mst->msg[0].buf = mst->i2c_write_buffer;
+	mst->msg[0].len = 4;
+
+	return i2c_transfer(mst->i2c_adap, mst->msg, 1) != 1 ? -EREMOTEIO : 0;
 }
 
 static u16 dibx000_read_word(struct dibx000_i2c_master *mst, u16 reg)
 {
-	u8 wb[2] = { reg >> 8, reg & 0xff };
-	u8 rb[2];
-	struct i2c_msg msg[2] = {
-		{.addr = mst->i2c_addr, .flags = 0, .buf = wb, .len = 2},
-		{.addr = mst->i2c_addr, .flags = I2C_M_RD, .buf = rb, .len = 2},
-	};
-
-	if (i2c_transfer(mst->i2c_adap, msg, 2) != 2)
+	mst->i2c_write_buffer[0] = reg >> 8;
+	mst->i2c_write_buffer[1] = reg & 0xff;
+
+	memset(mst->msg, 0, 2 * sizeof(struct i2c_msg));
+	mst->msg[0].addr = mst->i2c_addr;
+	mst->msg[0].flags = 0;
+	mst->msg[0].buf = mst->i2c_write_buffer;
+	mst->msg[0].len = 2;
+	mst->msg[1].addr = mst->i2c_addr;
+	mst->msg[1].flags = I2C_M_RD;
+	mst->msg[1].buf = mst->i2c_read_buffer;
+	mst->msg[1].len = 2;
+
+	if (i2c_transfer(mst->i2c_adap, mst->msg, 2) != 2)
 		dprintk("i2c read error on %d", reg);
 
-	return (rb[0] << 8) | rb[1];
+	return (mst->i2c_read_buffer[0] << 8) | mst->i2c_read_buffer[1];
 }
 
 static int dibx000_is_i2c_done(struct dibx000_i2c_master *mst)
@@ -248,26 +257,32 @@ static int dibx000_i2c_gated_gpio67_xfer(struct i2c_adapter *i2c_adap,
 					struct i2c_msg msg[], int num)
 {
 	struct dibx000_i2c_master *mst = i2c_get_adapdata(i2c_adap);
-	struct i2c_msg m[2 + num];
-	u8 tx_open[4], tx_close[4];
 
-	memset(m, 0, sizeof(struct i2c_msg) * (2 + num));
+	if (num > 32) {
+		dprintk("%s: too much I2C message to be transmitted (%i).\
+				Maximum is 32", __func__, num);
+		return -ENOMEM;
+	}
+
+	memset(mst->msg, 0, sizeof(struct i2c_msg) * (2 + num));
 
 	dibx000_i2c_select_interface(mst, DIBX000_I2C_INTERFACE_GPIO_6_7);
 
-	dibx000_i2c_gate_ctrl(mst, tx_open, msg[0].addr, 1);
-	m[0].addr = mst->i2c_addr;
-	m[0].buf = tx_open;
-	m[0].len = 4;
+	/* open the gate */
+	dibx000_i2c_gate_ctrl(mst, &mst->i2c_write_buffer[0], msg[0].addr, 1);
+	mst->msg[0].addr = mst->i2c_addr;
+	mst->msg[0].buf = &mst->i2c_write_buffer[0];
+	mst->msg[0].len = 4;
 
-	memcpy(&m[1], msg, sizeof(struct i2c_msg) * num);
+	memcpy(&mst->msg[1], msg, sizeof(struct i2c_msg) * num);
 
-	dibx000_i2c_gate_ctrl(mst, tx_close, 0, 0);
-	m[num + 1].addr = mst->i2c_addr;
-	m[num + 1].buf = tx_close;
-	m[num + 1].len = 4;
+	/* close the gate */
+	dibx000_i2c_gate_ctrl(mst, &mst->i2c_write_buffer[4], 0, 0);
+	mst->msg[num + 1].addr = mst->i2c_addr;
+	mst->msg[num + 1].buf = &mst->i2c_write_buffer[4];
+	mst->msg[num + 1].len = 4;
 
-	return i2c_transfer(mst->i2c_adap, m, 2 + num) == 2 + num ? num : -EIO;
+	return i2c_transfer(mst->i2c_adap, mst->msg, 2 + num) == 2 + num ? num : -EIO;
 }
 
 static struct i2c_algorithm dibx000_i2c_gated_gpio67_algo = {
@@ -279,26 +294,32 @@ static int dibx000_i2c_gated_tuner_xfer(struct i2c_adapter *i2c_adap,
 					struct i2c_msg msg[], int num)
 {
 	struct dibx000_i2c_master *mst = i2c_get_adapdata(i2c_adap);
-	struct i2c_msg m[2 + num];
-	u8 tx_open[4], tx_close[4];
 
-	memset(m, 0, sizeof(struct i2c_msg) * (2 + num));
+	if (num > 32) {
+		dprintk("%s: too much I2C message to be transmitted (%i).\
+				Maximum is 32", __func__, num);
+		return -ENOMEM;
+	}
+
+	memset(mst->msg, 0, sizeof(struct i2c_msg) * (2 + num));
 
 	dibx000_i2c_select_interface(mst, DIBX000_I2C_INTERFACE_TUNER);
 
-	dibx000_i2c_gate_ctrl(mst, tx_open, msg[0].addr, 1);
-	m[0].addr = mst->i2c_addr;
-	m[0].buf = tx_open;
-	m[0].len = 4;
+	/* open the gate */
+	dibx000_i2c_gate_ctrl(mst, &mst->i2c_write_buffer[0], msg[0].addr, 1);
+	mst->msg[0].addr = mst->i2c_addr;
+	mst->msg[0].buf = &mst->i2c_write_buffer[0];
+	mst->msg[0].len = 4;
 
-	memcpy(&m[1], msg, sizeof(struct i2c_msg) * num);
+	memcpy(&mst->msg[1], msg, sizeof(struct i2c_msg) * num);
 
-	dibx000_i2c_gate_ctrl(mst, tx_close, 0, 0);
-	m[num + 1].addr = mst->i2c_addr;
-	m[num + 1].buf = tx_close;
-	m[num + 1].len = 4;
+	/* close the gate */
+	dibx000_i2c_gate_ctrl(mst, &mst->i2c_write_buffer[4], 0, 0);
+	mst->msg[num + 1].addr = mst->i2c_addr;
+	mst->msg[num + 1].buf = &mst->i2c_write_buffer[4];
+	mst->msg[num + 1].len = 4;
 
-	return i2c_transfer(mst->i2c_adap, m, 2 + num) == 2 + num ? num : -EIO;
+	return i2c_transfer(mst->i2c_adap, mst->msg, 2 + num) == 2 + num ? num : -EIO;
 }
 
 static struct i2c_algorithm dibx000_i2c_gated_tuner_algo = {
diff --git a/drivers/media/dvb/frontends/dibx000_common.h b/drivers/media/dvb/frontends/dibx000_common.h
index 977d343369aa..f031165c0459 100644
--- a/drivers/media/dvb/frontends/dibx000_common.h
+++ b/drivers/media/dvb/frontends/dibx000_common.h
@@ -28,6 +28,11 @@ struct dibx000_i2c_master {
 	u8 i2c_addr;
 
 	u16 base_reg;
+
+	/* for the I2C transfer */
+	struct i2c_msg msg[34];
+	u8 i2c_write_buffer[8];
+	u8 i2c_read_buffer[2];
 };
 
 extern int dibx000_init_i2c_master(struct dibx000_i2c_master *mst,
-- 
2.39.5