[PATCH] fbdev: via: return an error when DMA copy times out

[PATCH] fbdev: via: return an error when DMA copy times out

[Pengpeng Hou]

viafb_dma_copy_out_sg() logs a VIA DMA timeout when the DONE bit is not
set after the completion wait and grace delay, but still returns success
to the caller.

Preserve the existing cleanup sequence and return -ETIMEDOUT when the DMA
engine did not report completion.

Signed-off-by: Pengpeng Hou <pengpeng@iscas.ac.cn>
---
 drivers/video/fbdev/via/via-core.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/video/fbdev/via/via-core.c b/drivers/video/fbdev/via/via-core.c
index a8d4a3e2c..ff691f83e 100644
--- a/drivers/video/fbdev/via/via-core.c
+++ b/drivers/video/fbdev/via/via-core.c
@@ -234,6 +234,7 @@ int viafb_dma_copy_out_sg(unsigned int offset, struct scatterlist *sg, int nsg)
 	dma_addr_t descr_handle;
 	unsigned long flags;
 	int i;
+	int ret = 0;
 	struct scatterlist *sgentry;
 	dma_addr_t nextdesc;
 
@@ -290,8 +291,10 @@ int viafb_dma_copy_out_sg(unsigned int offset, struct scatterlist *sg, int nsg)
 	 */
 	wait_for_completion_timeout(&viafb_dma_completion, 1);
 	msleep(1);
-	if ((viafb_mmio_read(VDMA_CSR0)&VDMA_C_DONE) == 0)
+	if ((viafb_mmio_read(VDMA_CSR0) & VDMA_C_DONE) == 0) {
 		printk(KERN_ERR "VIA DMA timeout!\n");
+		ret = -ETIMEDOUT;
+	}
 	/*
 	 * Clean up and we're done.
 	 */
@@ -301,7 +304,7 @@ int viafb_dma_copy_out_sg(unsigned int offset, struct scatterlist *sg, int nsg)
 	dma_free_coherent(&global_dev.pdev->dev,
 			nsg*sizeof(struct viafb_vx855_dma_descr), descrpages,
 			descr_handle);
-	return 0;
+	return ret;
 }
 EXPORT_SYMBOL_GPL(viafb_dma_copy_out_sg);
 #endif /* CONFIG_VIDEO_VIA_CAMERA */
-- 
2.50.1 (Apple Git-155)

Re: [PATCH] fbdev: via: return an error when DMA copy times out

[Helge Deller]

On 6/24/26 16:43, Pengpeng Hou wrote:
> viafb_dma_copy_out_sg() logs a VIA DMA timeout when the DONE bit is not
> set after the completion wait and grace delay, but still returns success
> to the caller.
> 
> Preserve the existing cleanup sequence and return -ETIMEDOUT when the DMA
> engine did not report completion.
> 
> Signed-off-by: Pengpeng Hou <pengpeng@iscas.ac.cn>
> ---
>   drivers/video/fbdev/via/via-core.c | 7 +++++--
>   1 file changed, 5 insertions(+), 2 deletions(-)

Note that the return value isn't checked by the caller.
Nevertheless, it's a cleanup, so I applied it.

Thanks!
Helge