Hi Hartmut,
Em Sun, 01 Nov 2009 16:59:26 +0100
e9hack <e9hack@xxxxxxxxxxxxxx> escreveu:
> Hi,
>
> something is wrong in changeset 13239:54535665f94b. After applying it, I get page faults
> in various applications:
> ...
>
> If I remove the call to release_all_pagetables() in buffer_release(), I don't see this
> page faults.
Em Mon, 2 Nov 2009 21:27:44 +0100
e9hack@xxxxxxxxxxxxxx escreveu:
> the BUG is in vidioc_streamoff() for the saa7146. This function
> releases all buffers first, and stops the capturing and dma tranfer of
> the saa7146 as second. If the page table, which is currently used by
> the saa7146, is modified by another thread, the saa7146 writes
> anywhere to the physical RAM. IMHO vidioc_streamoff() must stop the
> saa7146 first and may then release the buffers.
I agree. We need first to stop DMA activity, and then release the page tables.
Could you please test if the enclosed patch fixes the issue?
Cheers,
Mauro
saa7146: stop DMA before de-allocating DMA scatter/gather page buffers
Signed-off-by: Mauro Carvalho Chehab <mchehab@xxxxxxxxxx>
diff --git a/linux/drivers/media/common/saa7146_video.c b/linux/drivers/media/common/saa7146_video.c
--- a/linux/drivers/media/common/saa7146_video.c
+++ b/linux/drivers/media/common/saa7146_video.c
@@ -1334,9 +1334,9 @@ static void buffer_release(struct videob
DEB_CAP(("vbuf:%p\n",vb));
+ saa7146_dma_free(dev,q,buf);
+
release_all_pagetables(dev, buf);
-
- saa7146_dma_free(dev,q,buf);
}
static struct videobuf_queue_ops video_qops = {
--
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