linux-kernel - [PATCH 4.5 193/238] mmc: sdhci: fix command response CRC error handling

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Message-Id: <20160410183506.944274869@linuxfoundation.org>
Date:	Sun, 10 Apr 2016 11:36:10 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Russell King <rmk+kernel@....linux.org.uk>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Gregory CLEMENT <gregory.clement@...e-electrons.com>,
	Ulf Hansson <ulf.hansson@...aro.org>
Subject: [PATCH 4.5 193/238] mmc: sdhci: fix command response CRC error handling

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

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

From: Russell King <rmk+kernel@....linux.org.uk>

commit 71fcbda0fcddd0896c4982a484f6c8aa802d28b1 upstream.

When we get a response CRC error on a command, it means that the
response we received back from the card was not correct.  It does not
mean that the card did not receive the command correctly.  If the
command is one which initiates a data transfer, the card can enter the
data transfer state, and start sending data.

Moreover, if the request contained a data phase, we do not clean this
up, and this results in the driver triggering DMA API debug warnings,
and also creates a race condition in the driver, between running the
finish_tasklet and the data transfer interrupts, which can trigger a
"Got data interrupt" state dump.

Fix this by handing a response CRC error slightly differently: record
the failure of the data initiating command, but allow the remainder of
the request to be processed normally.  This is safe as core MMC checks
the status of all commands and data transfer phases of the request.

If the card does not initiate a data transfer, then we should time out
according to the data transfer parameters.

Signed-off-by: Russell King <rmk+kernel@....linux.org.uk>
[ Fix missing parenthesis around bitwise-AND expression, and tweak subject ]
Signed-off-by: Adrian Hunter <adrian.hunter@...el.com>
Tested-by: Gregory CLEMENT <gregory.clement@...e-electrons.com>
Signed-off-by: Ulf Hansson <ulf.hansson@...aro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/mmc/host/sdhci.c |   17 +++++++++++++++++
 1 file changed, 17 insertions(+)

--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -2330,6 +2330,23 @@ static void sdhci_cmd_irq(struct sdhci_h
 		else
 			host->cmd->error = -EILSEQ;

+		/*
+		 * If this command initiates a data phase and a response
+		 * CRC error is signalled, the card can start transferring
+		 * data - the card may have received the command without
+		 * error.  We must not terminate the mmc_request early.
+		 *
+		 * If the card did not receive the command or returned an
+		 * error which prevented it sending data, the data phase
+		 * will time out.
+		 */
+		if (host->cmd->data &&
+		    (intmask & (SDHCI_INT_CRC | SDHCI_INT_TIMEOUT)) ==
+		     SDHCI_INT_CRC) {
+			host->cmd = NULL;
+			return;
+		}
+
 		tasklet_schedule(&host->finish_tasklet);
 		return;
 	}