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    Subject[PATCH 061/104] mmc: tmio_mmc_dma: fix PIO fallback on SDHI
    Date
    3.5.7.22 -stable review patch.  If anyone has any objections, please let me know.

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

    From: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>

    commit f936f9b67b7f8c2eae01dd303a0e90bd777c4679 upstream.

    I'm testing SH-Mobile SDHI driver in DMA mode with a new DMA controller using
    'bonnie++' and getting DMA error after which the tmio_mmc_dma.c code falls back
    to PIO but all commands time out after that. It turned out that the fallback
    code calls tmio_mmc_enable_dma() with RX/TX channels already freed and pointers
    to them cleared, so that the function bails out early instead of clearing the
    DMA bit in the CTL_DMA_ENABLE register. The regression was introduced by commit
    162f43e31c5a376ec16336e5d0ac973373d54c89 (mmc: tmio: fix a deadlock).
    Moving tmio_mmc_enable_dma() calls to the top of the PIO fallback code in
    tmio_mmc_start_dma_{rx|tx}() helps.

    Signed-off-by: Sergei Shtylyov <sergei.shtylyov@cogentembedded.com>
    Acked-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
    Signed-off-by: Chris Ball <cjb@laptop.org>
    Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
    ---
    drivers/mmc/host/tmio_mmc_dma.c | 4 ++--
    1 file changed, 2 insertions(+), 2 deletions(-)

    diff --git a/drivers/mmc/host/tmio_mmc_dma.c b/drivers/mmc/host/tmio_mmc_dma.c
    index fff9286..491e9ec 100644
    --- a/drivers/mmc/host/tmio_mmc_dma.c
    +++ b/drivers/mmc/host/tmio_mmc_dma.c
    @@ -104,6 +104,7 @@ static void tmio_mmc_start_dma_rx(struct tmio_mmc_host *host)
    pio:
    if (!desc) {
    /* DMA failed, fall back to PIO */
    + tmio_mmc_enable_dma(host, false);
    if (ret >= 0)
    ret = -EIO;
    host->chan_rx = NULL;
    @@ -116,7 +117,6 @@ pio:
    }
    dev_warn(&host->pdev->dev,
    "DMA failed: %d, falling back to PIO\n", ret);
    - tmio_mmc_enable_dma(host, false);
    }

    dev_dbg(&host->pdev->dev, "%s(): desc %p, cookie %d, sg[%d]\n", __func__,
    @@ -185,6 +185,7 @@ static void tmio_mmc_start_dma_tx(struct tmio_mmc_host *host)
    pio:
    if (!desc) {
    /* DMA failed, fall back to PIO */
    + tmio_mmc_enable_dma(host, false);
    if (ret >= 0)
    ret = -EIO;
    host->chan_tx = NULL;
    @@ -197,7 +198,6 @@ pio:
    }
    dev_warn(&host->pdev->dev,
    "DMA failed: %d, falling back to PIO\n", ret);
    - tmio_mmc_enable_dma(host, false);
    }

    dev_dbg(&host->pdev->dev, "%s(): desc %p, cookie %d\n", __func__,
    --
    1.8.3.2


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