[PATCH 2/2] dmaengine: imx-sdma: fix cyclic buffer race condition

["Tomasz Moń" <tomasz.mon@camlingroup.com>]

Assign buffer ownership to SDMA after invoking descriptor callback to
make sure that SDMA does not write to the buffer before it is read by
the CPU.

Signed-off-by: Tomasz Moń <tomasz.mon@camlingroup.com>
---
 drivers/dma/imx-sdma.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/drivers/dma/imx-sdma.c b/drivers/dma/imx-sdma.c
index 330ff41cd614..8cc5103193c3 100644
--- a/drivers/dma/imx-sdma.c
+++ b/drivers/dma/imx-sdma.c
@@ -847,7 +847,6 @@ static void sdma_update_channel_loop(struct sdma_channel *sdmac)
 		*/
 
 		desc->chn_real_count = bd->mode.count;
-		bd->mode.status |= BD_DONE;
 		bd->mode.count = desc->period_len;
 		desc->buf_ptail = desc->buf_tail;
 		desc->buf_tail = (desc->buf_tail + 1) % desc->num_bd;
@@ -862,6 +861,9 @@ static void sdma_update_channel_loop(struct sdma_channel *sdmac)
 		dmaengine_desc_get_callback_invoke(&desc->vd.tx, NULL);
 		spin_lock(&sdmac->vc.lock);
 
+		/* Assign buffer ownership to SDMA */
+		bd->mode.status |= BD_DONE;
+
 		if (error)
 			sdmac->status = old_status;
 	}
-- 
2.25.1