Input: edt-ft5x06: prevent using on-stack buffer for I2C transfer

Using this driver with a DMA enabled I2C controller produces the
following warning (with CONFIG_DMA_API_DEBUG enabled):
|at91_i2c f8014000.i2c: DMA-API: device driver maps memory from stack [addr=8f847e29]

Prevent this by using a preallocated buffer.

diff --git a/drivers/input/touchscreen/edt-ft5x06.c b/drivers/input/touchscreen/edt-ft5x06.c
index e6aef3e48bd9207f982a73da37e60537c491835c..a1b08ea2d6f3a392e447d7610fbfb0fe378469b5 100644 (file)
--- a/drivers/input/touchscreen/edt-ft5x06.c
+++ b/drivers/input/touchscreen/edt-ft5x06.c
@@ -71,6 +71,8 @@
 #define EDT_RAW_DATA_RETRIES           100
 #define EDT_RAW_DATA_DELAY             1 /* msec */
 
+#define XFER_BUF_SIZE                  4
+
 enum edt_ver {
        M06,
        M09,
@@ -94,6 +96,7 @@ struct edt_ft5x06_ts_data {
        int reset_pin;
        int irq_pin;
        int wake_pin;
+       u8 xfer_buf[XFER_BUF_SIZE];
 
 #if defined(CONFIG_DEBUG_FS)
        struct dentry *debug_dir;
@@ -257,7 +260,7 @@ out:
 static int edt_ft5x06_register_write(struct edt_ft5x06_ts_data *tsdata,
                                     u8 addr, u8 value)
 {
-       u8 wrbuf[4];
+       u8 *wrbuf = &tsdata->xfer_buf[0];
 
        switch (tsdata->version) {
        case M06:
@@ -282,7 +285,8 @@ static int edt_ft5x06_register_write(struct edt_ft5x06_ts_data *tsdata,
 static int edt_ft5x06_register_read(struct edt_ft5x06_ts_data *tsdata,
                                    u8 addr)
 {
-       u8 wrbuf[2], rdbuf[2];
+       u8 *wrbuf = &tsdata->xfer_buf[0];
+       u8 *rdbuf = &tsdata->xfer_buf[2];
        int error;
 
        switch (tsdata->version) {
@@ -639,7 +643,7 @@ static ssize_t edt_ft5x06_debugfs_raw_data_read(struct file *file,
        int val, i, error;
        size_t read = 0;
        int colbytes;
-       char wrbuf[3];
+       char *wrbuf = &tsdata->xfer_buf[0];
        u8 *rdbuf;
 
        if (*off < 0 || *off >= tsdata->raw_bufsize)
@@ -687,8 +691,7 @@ static ssize_t edt_ft5x06_debugfs_raw_data_read(struct file *file,
        wrbuf[1] = 0x0e;
        for (i = 0; i < tsdata->num_x; i++) {
                wrbuf[2] = i;  /* column index */
-               error = edt_ft5x06_ts_readwrite(tsdata->client,
-                                               sizeof(wrbuf), wrbuf,
+               error = edt_ft5x06_ts_readwrite(tsdata->client, 4, wrbuf,
                                                colbytes, rdbuf);
                if (error)
                        goto out;
@@ -795,20 +798,19 @@ static int edt_ft5x06_ts_identify(struct i2c_client *client,
                                        struct edt_ft5x06_ts_data *tsdata,
                                        char *fw_version)
 {
-       u8 rdbuf[EDT_NAME_LEN];
+       u8 *rdbuf = kzalloc(EDT_NAME_LEN, GFP_KERNEL);
        char *p;
        int error;
        char *model_name = tsdata->name;
 
-       /* see what we find if we assume it is a M06 *
-        * if we get less than EDT_NAME_LEN, we don't want
-        * to have garbage in there
-        */
-       memset(rdbuf, 0, sizeof(rdbuf));
+       if (rdbuf == NULL)
+               return -ENOMEM;
+
+       /* see what we find if we assume it is an M06 */
        error = edt_ft5x06_ts_readwrite(client, 1, "\xbb",
                                        EDT_NAME_LEN - 1, rdbuf);
        if (error)
-               return error;
+               goto out;
 
        /* if we find something consistent, stay with that assumption
         * at least M09 won't send 3 bytes here
@@ -817,7 +819,6 @@ static int edt_ft5x06_ts_identify(struct i2c_client *client,
                tsdata->version = M06;
 
                /* remove last '$' end marker */
-               rdbuf[EDT_NAME_LEN - 1] = '\0';
                if (rdbuf[EDT_NAME_LEN - 2] == '$')
                        rdbuf[EDT_NAME_LEN - 2] = '\0';
 
@@ -834,20 +835,21 @@ static int edt_ft5x06_ts_identify(struct i2c_client *client,
                error = edt_ft5x06_ts_readwrite(client, 1, "\xA6",
                                                2, rdbuf);
                if (error)
-                       return error;
+                       goto out;
 
                strlcpy(fw_version, rdbuf, 2);
 
                error = edt_ft5x06_ts_readwrite(client, 1, "\xA8",
                                                1, rdbuf);
                if (error)
-                       return error;
+                       goto out;
 
                snprintf(model_name, EDT_NAME_LEN, "EP0%i%i0M09",
                        rdbuf[0] >> 4, rdbuf[0] & 0x0F);
        }
-
-       return 0;
+out:
+       kfree(rdbuf);
+       return error;
 }
 
 #define EDT_ATTR_CHECKSET(name, reg) \