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    Subject[PATCH 4.5 193/238] mmc: sdhci: fix command response CRC error handling
    Date
    4.5-stable review patch.  If anyone has any objections, please let me know.

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

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

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