[PATCH] mmc: core: Only set maximum DMA segment size if DMA is supported

[Guenter Roeck <linux@roeck-us.net>]

Since upstream commit 334304ac2bac ("dma-mapping: don't return errors
from dma_set_max_seg_size") calling dma_set_max_seg_size() on a device
not supporting DMA results in a warning traceback. This is seen when
booting the sifive_u machine from SD. The underlying SPI controller
(sifive,spi0 compatible) explicitly sets dma_mask to NULL.

Avoid the backtrace by only calling dma_set_max_seg_size() if DMA is
supported.

Cc: Christoph Hellwig <hch@lst.de>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Ulf Hansson <ulf.hansson@linaro.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
 drivers/mmc/core/queue.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/mmc/core/queue.c b/drivers/mmc/core/queue.c
index d0b3ca8a11f0..4d6844261912 100644
--- a/drivers/mmc/core/queue.c
+++ b/drivers/mmc/core/queue.c
@@ -388,7 +388,8 @@ static struct gendisk *mmc_alloc_disk(struct mmc_queue *mq,
 
 	blk_queue_rq_timeout(mq->queue, 60 * HZ);
 
-	dma_set_max_seg_size(mmc_dev(host), queue_max_segment_size(mq->queue));
+	if (mmc_dev(host)->dma_parms)
+		dma_set_max_seg_size(mmc_dev(host), queue_max_segment_size(mq->queue));
 
 	INIT_WORK(&mq->recovery_work, mmc_mq_recovery_handler);
 	INIT_WORK(&mq->complete_work, mmc_blk_mq_complete_work);
-- 
2.45.2