On Sat, 3 Aug 2013, Sergei Shtylyov wrote:
> 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 <[email protected]>
> Cc: [email protected] # 3.1+
Acked-by: Guennadi Liakhovetski <[email protected]>
Not sure though how far back in stable this really has to go. We don't
have any real-life problem reports with older kernels, do we? I think
approach to which patches should get into stable changed recently.
Thanks
Guennadi
>
> ---
> The patch is against Chris Ball's 'mmc.git' repo, 'master' branch.
>
> Changes in version 2:
> - removed extra check from tmio_mmc_enable_dma();
> - moved tmio_mmc_enable_dma() calls to the top of the PIO fallback code in
> tmio_mmc_start_dma_{rx|tx}().
>
> drivers/mmc/host/tmio_mmc_dma.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> Index: renesas/drivers/mmc/host/tmio_mmc_dma.c
> ===================================================================
> --- renesas.orig/drivers/mmc/host/tmio_mmc_dma.c
> +++ renesas/drivers/mmc/host/tmio_mmc_dma.c
> @@ -104,6 +104,7 @@ static void tmio_mmc_start_dma_rx(struct
> 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
> 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__,
> --
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>
---
Guennadi Liakhovetski, Ph.D.
Freelance Open-Source Software Developer
http://www.open-technology.de/
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