mmc: rtsx_pci_sdmmc: fix incorrect last byte in R2 response

Current code erroneously fill the last byte of R2 response with an undefined
value. In addition, the controller actually 'offloads' the last byte
(CRC7, end bit) while receiving R2 response and thus it's impossible to get the
actual value. This could cause mmc stack to obtain inconsistent CID from the
same card after resume and misidentify it as a different card.

Fix by assigning dummy CRC and end bit: {7'b0, 1} = 0x1 to the last byte of R2.

Cc: <stable@vger.kernel.org> # v3.8+
Fixes: ff984e57d36e ("mmc: Add realtek pcie sdmmc host driver")
Signed-off-by: Roger Tseng <rogerable@realtek.com>
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

diff --git a/drivers/mmc/host/rtsx_pci_sdmmc.c b/drivers/mmc/host/rtsx_pci_sdmmc.c
index dfde4a21023864ae26aa68336001772d51e41209..b2537e2f26b1992e3ba7618e9624213df9036f67 100644 (file)
--- a/drivers/mmc/host/rtsx_pci_sdmmc.c
+++ b/drivers/mmc/host/rtsx_pci_sdmmc.c
@@ -412,6 +412,13 @@ static void sd_send_cmd_get_rsp(struct realtek_pci_sdmmc *host,
        }
 
        if (rsp_type == SD_RSP_TYPE_R2) {
+               /*
+                * The controller offloads the last byte {CRC-7, end bit 1'b1}
+                * of response type R2. Assign dummy CRC, 0, and end bit to the
+                * byte(ptr[16], goes into the LSB of resp[3] later).
+                */
+               ptr[16] = 1;
+
                for (i = 0; i < 4; i++) {
                        cmd->resp[i] = get_unaligned_be32(ptr + 1 + i * 4);
                        dev_dbg(sdmmc_dev(host), "cmd->resp[%d] = 0x%08x\n",