[ 3.5.y.z extended stable ] Patch "mmc: tmio_mmc_dma: fix PIO fallback on SDHI" has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    mmc: tmio_mmc_dma: fix PIO fallback on SDHI

to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.5.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From b56867e95ab2486149c763833becb00cbbe112c3 Mon Sep 17 00:00:00 2001
From: Sergei Shtylyov <sergei.shtylyov at cogentembedded.com>
Date: Sat, 24 Aug 2013 23:38:15 -0400
Subject: [PATCH] mmc: tmio_mmc_dma: fix PIO fallback on SDHI

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 at cogentembedded.com>
Acked-by: Guennadi Liakhovetski <g.liakhovetski at gmx.de>
Signed-off-by: Chris Ball <cjb at laptop.org>
Signed-off-by: Luis Henriques <luis.henriques at 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