mmc: atmel-mci: fix timeout errors in SDIO mode when using DMA
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.
Cc: stable <stable@vger.kernel.org> # 3.2+
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>
diff --git a/drivers/mmc/host/atmel-mci.c b/drivers/mmc/host/atmel-mci.c
index 2cbb451..945a31d 100644
--- a/drivers/mmc/host/atmel-mci.c
+++ b/drivers/mmc/host/atmel-mci.c
@@ -1192,11 +1192,22 @@
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;
