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    Subject[PATCH AUTOSEL 4.20 182/304] mmc: bcm2835: Recover from MMC_SEND_EXT_CSD
    Date
    From: Phil Elwell <phil@raspberrypi.org>

    [ Upstream commit 07d405769afea5718529fc9e341f0b13b3189b6f ]

    If the user issues an "mmc extcsd read", the SD controller receives
    what it thinks is a SEND_IF_COND command with an unexpected data block.
    The resulting operations leave the FSM stuck in READWAIT, a state which
    persists until the MMC framework resets the controller, by which point
    the root filesystem is likely to have been unmounted.

    A less heavyweight solution is to detect the condition and nudge the
    FSM by asserting the (self-clearing) FORCE_DATA_MODE bit.

    Link: https://github.com/raspberrypi/linux/issues/2728
    Signed-off-by: Phil Elwell <phil@raspberrypi.org>
    Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
    Acked-by: Eric Anholt <eric@anholt.net>
    Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>
    Signed-off-by: Sasha Levin <sashal@kernel.org>
    ---
    drivers/mmc/host/bcm2835.c | 9 +++++++++
    1 file changed, 9 insertions(+)

    diff --git a/drivers/mmc/host/bcm2835.c b/drivers/mmc/host/bcm2835.c
    index 768972af8b85..aef40e1739ee 100644
    --- a/drivers/mmc/host/bcm2835.c
    +++ b/drivers/mmc/host/bcm2835.c
    @@ -772,6 +772,8 @@ static void bcm2835_finish_command(struct bcm2835_host *host)

    if (!(sdhsts & SDHSTS_CRC7_ERROR) ||
    (host->cmd->opcode != MMC_SEND_OP_COND)) {
    + u32 edm, fsm;
    +
    if (sdhsts & SDHSTS_CMD_TIME_OUT) {
    host->cmd->error = -ETIMEDOUT;
    } else {
    @@ -780,6 +782,13 @@ static void bcm2835_finish_command(struct bcm2835_host *host)
    bcm2835_dumpregs(host);
    host->cmd->error = -EILSEQ;
    }
    + edm = readl(host->ioaddr + SDEDM);
    + fsm = edm & SDEDM_FSM_MASK;
    + if (fsm == SDEDM_FSM_READWAIT ||
    + fsm == SDEDM_FSM_WRITESTART1)
    + /* Kick the FSM out of its wait */
    + writel(edm | SDEDM_FORCE_DATA_MODE,
    + host->ioaddr + SDEDM);
    bcm2835_finish_request(host);
    return;
    }
    --
    2.19.1
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