There are several situations when dw_mci_submit_data_dma() decides to
fall back to PIO mode instead of using DMA, due to a short (to avoid
overhead) or "complex" (e.g. with unaligned buffers) transaction, even
though host->use_dma is set. However dw_mci_stop_dma() decides whether
to stop DMA or set the EVENT_XFER_COMPLETE event based on host->use_dma.
When falling back to PIO mode this results in data timeout errors
getting missed and the driver locking up.
Therefore add host->using_dma to indicate whether the current
transaction is using dma or not, and adjust dw_mci_stop_dma() to use
that instead.
Signed-off-by: James Hogan <james.hogan@xxxxxxxxxx>
---
drivers/mmc/host/dw_mmc.c | 6 +++++-
include/linux/mmc/dw_mmc.h | 2 ++
2 files changed, 7 insertions(+), 1 deletions(-)
diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
index 10b6979..fcff3c0 100644
--- a/drivers/mmc/host/dw_mmc.c
+++ b/drivers/mmc/host/dw_mmc.c
@@ -287,7 +287,7 @@ static void send_stop_cmd(struct dw_mci *host, struct mmc_data *data)
/* DMA interface functions */
static void dw_mci_stop_dma(struct dw_mci *host)
{
- if (host->use_dma) {
+ if (host->using_dma) {
host->dma_ops->stop(host);
host->dma_ops->cleanup(host);
} else {
@@ -435,6 +435,8 @@ static int dw_mci_submit_data_dma(struct dw_mci *host, struct mmc_data *data)
unsigned int i, direction, sg_len;
u32 temp;
+ host->using_dma = 0;
+
/* If we don't have a channel, we can't do DMA */
if (!host->use_dma)
return -ENODEV;
@@ -454,6 +456,8 @@ static int dw_mci_submit_data_dma(struct dw_mci *host, struct mmc_data *data)
return -EINVAL;
}
+ host->using_dma = 1;
+
if (data->flags & MMC_DATA_READ)
direction = DMA_FROM_DEVICE;
else
diff --git a/include/linux/mmc/dw_mmc.h b/include/linux/mmc/dw_mmc.h
index f3f68ee..6b46819 100644
--- a/include/linux/mmc/dw_mmc.h
+++ b/include/linux/mmc/dw_mmc.h
@@ -48,6 +48,7 @@ struct mmc_data;
* @data: The data currently being transferred, or NULL if no data
* transfer is in progress.
* @use_dma: Whether DMA channel is initialized or not.
+ * @using_dma: Whether DMA is in use for the current transfer.
* @sg_dma: Bus address of DMA buffer.
* @sg_cpu: Virtual address of DMA buffer.
* @dma_ops: Pointer to platform-specific DMA callbacks.
@@ -121,6 +122,7 @@ struct dw_mci {
/* DMA interface members*/
int use_dma;
+ int using_dma;
dma_addr_t sg_dma;
void *sg_cpu;
--
1.7.2.3
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