[PATCH 4.20 081/145] spi: bcm2835: Fix book-keeping of DMA termination

From: Greg Kroah-Hartman
Date: Mon Jan 07 2019 - 07:40:36 EST

4.20-stable review patch. If anyone has any objections, please let me know.


From: Lukas Wunner <lukas@xxxxxxxxx>

commit dbc944115eed48af110646992893dc43321368d8 upstream.

If submission of a DMA TX transfer succeeds but submission of the
corresponding RX transfer does not, the BCM2835 SPI driver terminates
the TX transfer but neglects to reset the dma_pending flag to false.

Thus, if the next transfer uses interrupt mode (because it is shorter
than BCM2835_SPI_DMA_MIN_LENGTH) and runs into a timeout,
dmaengine_terminate_all() will be called both for TX (once more) and
for RX (which was never started in the first place). Fix it.

Signed-off-by: Lukas Wunner <lukas@xxxxxxxxx>
Fixes: 3ecd37edaa2a ("spi: bcm2835: enable dma modes for transfers meeting certain conditions")
Cc: stable@xxxxxxxxxxxxxxx # v4.2+
Cc: Mathias Duckeck <m.duckeck@xxxxxxxxx>
Cc: Frank Pavlic <f.pavlic@xxxxxxxxx>
Cc: Martin Sperl <kernel@xxxxxxxxxxxxxxxx>
Cc: Noralf TrÃnnes <noralf@xxxxxxxxxxx>
Signed-off-by: Mark Brown <broonie@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

drivers/spi/spi-bcm2835.c | 1 +
1 file changed, 1 insertion(+)

--- a/drivers/spi/spi-bcm2835.c
+++ b/drivers/spi/spi-bcm2835.c
@@ -341,6 +341,7 @@ static int bcm2835_spi_transfer_one_dma(
if (ret) {
/* need to reset on errors */
+ bs->dma_pending = false;
return ret;