dmaengine: sprd: Fix the incorrect start for 2-stage destination channels [Linux 5.2]

dmaengine: sprd: Fix the incorrect start for 2-stage destination channels [Linux 5.2]

This Linux kernel change "dmaengine: sprd: Fix the incorrect start for 2-stage destination channels" is included in the Linux 5.2 release. This change is authored by Eric Long <eric.long [at] unisoc.com> on Mon May 6 15:28:30 2019 +0800. The commit for this change in Linux stable tree is 3d626a9 (patch).

dmaengine: sprd: Fix the incorrect start for 2-stage destination channels

The 2-stage destination channel will be triggered by source channel
automatically, which means we should not trigger it by software request.

Signed-off-by: Eric Long <[email protected]>
Signed-off-by: Baolin Wang <[email protected]>
Signed-off-by: Vinod Koul <[email protected]>

There are 4 lines of Linux source code added/deleted in this change. Code changes to Linux kernel are as follows.

 drivers/dma/sprd-dma.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/dma/sprd-dma.c b/drivers/dma/sprd-dma.c
index 431e289..0f92e60 100644
--- a/drivers/dma/sprd-dma.c
+++ b/drivers/dma/sprd-dma.c
@@ -510,7 +510,9 @@ static void sprd_dma_start(struct sprd_dma_chn *schan)
    sprd_dma_set_uid(schan);
    sprd_dma_enable_chn(schan);

-   if (schan->dev_id == SPRD_DMA_SOFTWARE_UID)
+   if (schan->dev_id == SPRD_DMA_SOFTWARE_UID &&
+       schan->chn_mode != SPRD_DMA_DST_CHN0 &&
+       schan->chn_mode != SPRD_DMA_DST_CHN1)
        sprd_dma_soft_request(schan);
 }

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