linux-kernel - [PATCH 3.13 014/105] mmc: rtsx_pci_sdmmc: fix incorrect last byte in R2 response

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Message-Id: <1414436240-13879-15-git-send-email-kamal@canonical.com>
Date:	Mon, 27 Oct 2014 11:55:49 -0700
From:	Kamal Mostafa <kamal@...onical.com>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org,
	kernel-team@...ts.ubuntu.com
Cc:	Roger Tseng <rogerable@...ltek.com>,
	Ulf Hansson <ulf.hansson@...aro.org>,
	Kamal Mostafa <kamal@...onical.com>
Subject: [PATCH 3.13 014/105] mmc: rtsx_pci_sdmmc: fix incorrect last byte in R2 response

3.13.11.10 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Roger Tseng <rogerable@...ltek.com>

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@...ltek.com>
Signed-off-by: Ulf Hansson <ulf.hansson@...aro.org>
Signed-off-by: Kamal Mostafa <kamal@...onical.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",
-- 
1.9.1

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