mmc: sdio: fix setting card data bus width as 4-bit

SDIO_CCCR_IF[1:0] in SDIO card is used for card data bus width
setting as below:

     00b: 1-bit bus
     01b: Reserved
     10b: 4-bit bus
     11b: 8-bit bus (only for embedded SDIO)

And sdio_enable_wide is for setting data bus width as 4-bit.
But currently, it first reads the register, second OR' 1b with
SDIO_CCCR_IF[1], and then writes it back.

As we can see, this is based on such assumption that the
SDIO_CCCR_IF[0] is always 0. Apparently, this is not right.

Signed-off-by: Yong Ding <yongd@marvell.com>
Acked-by: Philip Rakity <prakity@marvell.com>
Signed-off-by: Chris Ball <cjb@laptop.org>

diff --git a/drivers/mmc/core/sdio.c b/drivers/mmc/core/sdio.c
index 13d0e95380ab8f73d601060c3415b82bb253d12b..41c5fd8848f4d72c171d9e001b2171607e13eb83 100644 (file)
--- a/drivers/mmc/core/sdio.c
+++ b/drivers/mmc/core/sdio.c
@@ -218,6 +218,12 @@ static int sdio_enable_wide(struct mmc_card *card)
        if (ret)
                return ret;
 
+       if ((ctrl & SDIO_BUS_WIDTH_MASK) == SDIO_BUS_WIDTH_RESERVED)
+               pr_warning("%s: SDIO_CCCR_IF is invalid: 0x%02x\n",
+                          mmc_hostname(card->host), ctrl);
+
+       /* set as 4-bit bus width */
+       ctrl &= ~SDIO_BUS_WIDTH_MASK;
        ctrl |= SDIO_BUS_WIDTH_4BIT;
 
        ret = mmc_io_rw_direct(card, 1, 0, SDIO_CCCR_IF, ctrl, NULL);

diff --git a/include/linux/mmc/sdio.h b/include/linux/mmc/sdio.h
index c9fe66c58f8fc718e68b2147733a0acab750d5aa..17446d3c36027ccac99f70c097af2948390800ec 100644 (file)
--- a/include/linux/mmc/sdio.h
+++ b/include/linux/mmc/sdio.h
@@ -98,7 +98,9 @@
 
 #define SDIO_CCCR_IF           0x07    /* bus interface controls */
 
+#define  SDIO_BUS_WIDTH_MASK   0x03    /* data bus width setting */
 #define  SDIO_BUS_WIDTH_1BIT   0x00
+#define  SDIO_BUS_WIDTH_RESERVED 0x01
 #define  SDIO_BUS_WIDTH_4BIT   0x02
 #define  SDIO_BUS_ECSI         0x20    /* Enable continuous SPI interrupt */
 #define  SDIO_BUS_SCSI         0x40    /* Support continuous SPI interrupt */