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mmc: atmel-mci: fix timeout errors in SDIO mode when using DMA

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commit 66b512eda7 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@atmel.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>
Signed-off-by: Chris Ball <cjb@laptop.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Ludovic Desroches 2013-11-20 16:01:11 +01:00 • committed by Greg Kroah-Hartman
commit 6bf1831dae
1 changed files with 12 additions and 1 deletions
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13
drivers/mmc/host/atmel-mci.c
View file

@ -1188,11 +1188,22 @@ static void atmci_start_request(struct atmel_mci *host,
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;