[PATCH 17/33] dmaengine: at_hdmac: Fix descriptor handling when issuing it to hardware

Tudor Ambarus
2022-08-20T12:59:28Z

As it was before, the descriptor was issued to the hardware without adding
it to the active (issued) list. This could result in a completion of other
descriptor, or/and in the descriptor never being completed.

Fixes: dc78baa2b90b ("dmaengine: at_hdmac: new driver for the Atmel AHB DMA Controller")
Reported-by: Peter Rosin <peda@axentia.se>
Cc: stable@vger.kernel.org
Signed-off-by: Tudor Ambarus <tudor.ambarus@microchip.com>
Link: https://lore.kernel.org/lkml/13c6c9a2-6db5-c3bf-349b-4c127ad3496a@axentia.se/
---
drivers/dma/at_hdmac.c | 15 +++++++++++----
1 file changed, 11 insertions(+), 4 deletions(-)

diff --git a/drivers/dma/at_hdmac.c b/drivers/dma/at_hdmac.c
index 635c3be74399..e5ac73768d13 100644
--- a/drivers/dma/at_hdmac.c
+++ b/drivers/dma/at_hdmac.c
@@ -945,8 +945,11 @@ static void atc_advance_work(struct at_dma_chan *atchan)

/* advance work */
spin_lock_irqsave(&atchan->lock, flags);
- if (!list_empty(&atchan->active_list))
- atc_dostart(atchan, atc_first_active(atchan));
+ if (!list_empty(&atchan->active_list)) {
+ desc = atc_first_queued(atchan);
+ list_move_tail(&desc->desc_node, &atchan->active_list);
+ atc_dostart(atchan, desc);
+ }
spin_unlock_irqrestore(&atchan->lock, flags);
}

@@ -958,6 +961,7 @@ static void atc_advance_work(struct at_dma_chan *atchan)
static void atc_handle_error(struct at_dma_chan *atchan)
{
struct at_desc *bad_desc;
+ struct at_desc *desc;
struct at_desc *child;
unsigned long flags;

@@ -975,8 +979,11 @@ static void atc_handle_error(struct at_dma_chan *atchan)
list_splice_init(&atchan->queue, atchan->active_list.prev);

/* Try to restart the controller */
- if (!list_empty(&atchan->active_list))
- atc_dostart(atchan, atc_first_active(atchan));
+ if (!list_empty(&atchan->active_list)) {
+ desc = atc_first_queued(atchan);
+ list_move_tail(&desc->desc_node, &atchan->active_list);
+ atc_dostart(atchan, desc);
+ }

/*
* KERN_CRITICAL may seem harsh, but since this only happens
--
2.25.1