Hi,
On 28/02/2024 06:21, Vishal Sagar wrote:
From: Neel Gandhi <neel.gandhi@xxxxxxxxxx>
The vchan_next_desc() function, called from
xilinx_dpdma_chan_queue_transfer(), must be called with
virt_dma_chan.lock held. This isn't correctly handled in all code paths,
resulting in a race condition between the .device_issue_pending()
handler and the IRQ handler which causes DMA to randomly stop. Fix it by
taking the lock around xilinx_dpdma_chan_queue_transfer() calls that are
missing it.
Signed-off-by: Neel Gandhi <neel.gandhi@xxxxxxx>
Signed-off-by: Radhey Shyam Pandey <radhey.shyam.pandey@xxxxxxx>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@xxxxxxxxxxxxxxxx>
Signed-off-by: Vishal Sagar <vishal.sagar@xxxxxxx>
Link: https://lore.kernel.org/all/20220122121407.11467-1-neel.gandhi@xxxxxxxxxx
---
drivers/dma/xilinx/xilinx_dpdma.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
This fixes a lockdep warning:
WARNING: CPU: 1 PID: 466 at drivers/dma/xilinx/xilinx_dpdma.c:834
Afaics, this issue has been around since the initial commit, in v5.10,
and the fix applies on top of v5.10. I have tested this on v6.2, which
is where the DP support was added to the board I have.
So I think you can add:
Fixes: 7cbb0c63de3f ("dmaengine: xilinx: dpdma: Add the Xilinx
DisplayPort DMA engine driver")
Tomi
diff --git a/drivers/dma/xilinx/xilinx_dpdma.c b/drivers/dma/xilinx/xilinx_dpdma.c
index b82815e64d24..28d9af8f00f0 100644
--- a/drivers/dma/xilinx/xilinx_dpdma.c
+++ b/drivers/dma/xilinx/xilinx_dpdma.c
@@ -1097,12 +1097,14 @@ static void xilinx_dpdma_chan_vsync_irq(struct xilinx_dpdma_chan *chan)
* Complete the active descriptor, if any, promote the pending
* descriptor to active, and queue the next transfer, if any.
*/
+ spin_lock(&chan->vchan.lock);
if (chan->desc.active)
vchan_cookie_complete(&chan->desc.active->vdesc);
chan->desc.active = pending;
chan->desc.pending = NULL;
xilinx_dpdma_chan_queue_transfer(chan);
+ spin_unlock(&chan->vchan.lock);
out:
spin_unlock_irqrestore(&chan->lock, flags);
@@ -1264,10 +1266,12 @@ static void xilinx_dpdma_issue_pending(struct dma_chan *dchan)
struct xilinx_dpdma_chan *chan = to_xilinx_chan(dchan);
unsigned long flags;
- spin_lock_irqsave(&chan->vchan.lock, flags);
+ spin_lock_irqsave(&chan->lock, flags);
+ spin_lock(&chan->vchan.lock);
if (vchan_issue_pending(&chan->vchan))
xilinx_dpdma_chan_queue_transfer(chan);
- spin_unlock_irqrestore(&chan->vchan.lock, flags);
+ spin_unlock(&chan->vchan.lock);
+ spin_unlock_irqrestore(&chan->lock, flags);
}
static int xilinx_dpdma_config(struct dma_chan *dchan,
@@ -1495,7 +1499,9 @@ static void xilinx_dpdma_chan_err_task(struct tasklet_struct *t)
XILINX_DPDMA_EINTR_CHAN_ERR_MASK << chan->id);
spin_lock_irqsave(&chan->lock, flags);
+ spin_lock(&chan->vchan.lock);
xilinx_dpdma_chan_queue_transfer(chan);
+ spin_unlock(&chan->vchan.lock);
spin_unlock_irqrestore(&chan->lock, flags);
}
