From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To: dmaengine@vger.kernel.org
Cc: Vinod Koul <vkoul@kernel.org>,
Michal Simek <michal.simek@xilinx.com>,
Jianqiang Chen <jianqian@xilinx.com>,
linux-arm-kernel@lists.infradead.org
Subject: [PATCH 3/4] dmaengine: xilinx: dpdma: Print debug message when losing vsync race
Date: Thu, 20 May 2021 18:24:19 +0300 [thread overview]
Message-ID: <20210520152420.23986-4-laurent.pinchart@ideasonboard.com> (raw)
In-Reply-To: <20210520152420.23986-1-laurent.pinchart@ideasonboard.com>
The hardware retrigger is inherently racy with the vsync interrupt. This
isn't an issue as the hardware provides a way to detect a race loss and
handle it correctly. When debugging issues related to this, it's useful
to get a notification of the race loss. Add a debug message to do so.
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
---
drivers/dma/xilinx/xilinx_dpdma.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/drivers/dma/xilinx/xilinx_dpdma.c b/drivers/dma/xilinx/xilinx_dpdma.c
index ea56c3b35782..5834f8614a58 100644
--- a/drivers/dma/xilinx/xilinx_dpdma.c
+++ b/drivers/dma/xilinx/xilinx_dpdma.c
@@ -1095,8 +1095,12 @@ static void xilinx_dpdma_chan_vsync_irq(struct xilinx_dpdma_chan *chan)
/* If the retrigger raced with vsync, retry at the next frame. */
sw_desc = list_first_entry(&pending->descriptors,
struct xilinx_dpdma_sw_desc, node);
- if (sw_desc->hw.desc_id != desc_id)
+ if (sw_desc->hw.desc_id != desc_id) {
+ dev_dbg(chan->xdev->dev,
+ "chan%u: vsync race lost (%u != %u), retrying\n",
+ chan->id, sw_desc->hw.desc_id, desc_id);
goto out;
+ }
/*
* Complete the active descriptor, if any, promote the pending
--
Regards,
Laurent Pinchart
next prev parent reply other threads:[~2021-05-20 15:25 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-05-20 15:24 [PATCH 0/4] dmaengine: xilinx: dpdma: Fix freeze after 64k frames Laurent Pinchart
2021-05-20 15:24 ` [PATCH 1/4] dmaengine: xilinx: dpdma: Add missing dependencies to Kconfig Laurent Pinchart
2021-05-20 15:24 ` [PATCH 2/4] dmaengine: xilinx: dpdma: Print channel number in kernel log messages Laurent Pinchart
2021-05-20 15:24 ` Laurent Pinchart [this message]
2021-05-20 15:24 ` [PATCH 4/4] dmaengine: xilinx: dpdma: Limit descriptor IDs to 16 bits Laurent Pinchart
2021-05-27 16:35 ` [PATCH 0/4] dmaengine: xilinx: dpdma: Fix freeze after 64k frames Jianqiang Chen
2021-05-31 4:08 ` Vinod Koul
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