This is a note to let you know that I've just added the patch titled
mmc: atmel-mci: fix timeout errors in SDIO mode when using DMA
to the 3.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
mmc-atmel-mci-fix-timeout-errors-in-sdio-mode-when-using-dma.patch
and it can be found in the queue-3.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 66b512eda74d59b17eac04c4da1b38d82059e6c9 Mon Sep 17 00:00:00 2001
From: Ludovic Desroches <ludovic.desroches@xxxxxxxxx>
Date: Wed, 20 Nov 2013 16:01:11 +0100
Subject: mmc: atmel-mci: fix timeout errors in SDIO mode when using DMA
From: Ludovic Desroches <ludovic.desroches@xxxxxxxxx>
commit 66b512eda74d59b17eac04c4da1b38d82059e6c9 upstream.
With some SDIO devices, timeout errors can happen when reading data.
To solve this issue, the DMA transfer has to be activated before sending
the command to the device. This order is incorrect in PDC mode. So we
have to take care if we are using DMA or PDC to know when to send the
MMC command.
Signed-off-by: Ludovic Desroches <ludovic.desroches@xxxxxxxxx>
Acked-by: Nicolas Ferre <nicolas.ferre@xxxxxxxxx>
Signed-off-by: Chris Ball <cjb@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/mmc/host/atmel-mci.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)
--- a/drivers/mmc/host/atmel-mci.c
+++ b/drivers/mmc/host/atmel-mci.c
@@ -1022,11 +1022,22 @@ static void atmci_start_request(struct a
iflags |= ATMCI_CMDRDY;
cmd = mrq->cmd;
cmdflags = atmci_prepare_command(slot->mmc, cmd);
- atmci_send_command(host, cmd, cmdflags);
+
+ /*
+ * DMA transfer should be started before sending the command to avoid
+ * unexpected errors especially for read operations in SDIO mode.
+ * Unfortunately, in PDC mode, command has to be sent before starting
+ * the transfer.
+ */
+ if (host->submit_data != &atmci_submit_data_dma)
+ atmci_send_command(host, cmd, cmdflags);
if (data)
host->submit_data(host, data);
+ if (host->submit_data == &atmci_submit_data_dma)
+ atmci_send_command(host, cmd, cmdflags);
+
if (mrq->stop) {
host->stop_cmdr = atmci_prepare_command(slot->mmc, mrq->stop);
host->stop_cmdr |= ATMCI_CMDR_STOP_XFER;
Patches currently in stable-queue which might be from ludovic.desroches@xxxxxxxxx are
queue-3.4/mmc-atmel-mci-fix-timeout-errors-in-sdio-mode-when-using-dma.patch
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