[3.13.y.z extended stable] Patch "mmc: rtsx_pci_sdmmc: fix incorrect last byte in R2 response" has been added to staging queue

Kamal Mostafa kamal at canonical.com
Tue Oct 21 20:09:11 UTC 2014

This is a note to let you know that I have just added a patch titled

    mmc: rtsx_pci_sdmmc: fix incorrect last byte in R2 response

to the linux-3.13.y-queue branch of the 3.13.y.z extended stable tree 
which can be found at:


This patch is scheduled to be released in version

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.13.y.z tree, see



>From 02323579069ef76a28aa085a55319b138019f3db Mon Sep 17 00:00:00 2001
From: Roger Tseng <rogerable at realtek.com>
Date: Fri, 15 Aug 2014 14:06:00 +0800
Subject: mmc: rtsx_pci_sdmmc: fix incorrect last byte in R2 response

commit d1419d50c1bf711e9fd27b516a739c86b23f7cf9 upstream.

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.

Fixes: ff984e57d36e ("mmc: Add realtek pcie sdmmc host driver")
Signed-off-by: Roger Tseng <rogerable at realtek.com>
Signed-off-by: Ulf Hansson <ulf.hansson at linaro.org>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
 drivers/mmc/host/rtsx_pci_sdmmc.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/mmc/host/rtsx_pci_sdmmc.c b/drivers/mmc/host/rtsx_pci_sdmmc.c
index c46feda..bdbac02 100644
--- a/drivers/mmc/host/rtsx_pci_sdmmc.c
+++ b/drivers/mmc/host/rtsx_pci_sdmmc.c
@@ -339,6 +339,13 @@ 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",

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