This seems ok. This portion of code was based on vivi.c, so that might
be checked also.
Mike Isely wrote:
# HG changeset patch
# User Mike Isely <isely@xxxxxxxxx>
# Date 1253739604 18000
# Node ID 522a74147753ba59c7f45e368439928090a286f2
# Parent e349075171ddf939381fad432c23c1269abc4899
s2255drv: Don't conditionalize video buffer completion on waiting processes
From: Mike Isely <isely@xxxxxxxxx>
The s2255 driver had logic which aborted processing of a video frame
if there was no process waiting on the video buffer in question. That
simply doesn't work when the application is doing things in an
asynchronous manner. If the application went to the trouble to queue
the buffer in the first place, then the driver should always attempt
to complete it - even if the application at that moment has its
attention turned elsewhere. Applications which always blocked waiting
for I/O on the capture device would not have been affected by this.
Applications which *mostly* blocked waiting for I/O on the capture
device probably only would have been somewhat affected (frame lossage,
at a rate which goes up as the application blocks less). Applications
which never blocked on the capture device (e.g. polling only) however
would never have been able to receive any video frames, since in that
case this "is anyone waiting on this?" check on the buffer never would
have evalutated true. This patch just deletes that harmful check
against the buffer's wait queue.
Priority: high
Signed-off-by: Mike Isely <isely@xxxxxxxxx>
diff -r e349075171dd -r 522a74147753 linux/drivers/media/video/s2255drv.c
--- a/linux/drivers/media/video/s2255drv.c Mon Sep 21 10:42:22 2009 -0500
+++ b/linux/drivers/media/video/s2255drv.c Wed Sep 23 16:00:04 2009 -0500
@@ -599,11 +599,6 @@
buf = list_entry(dma_q->active.next,
struct s2255_buffer, vb.queue);
- if (!waitqueue_active(&buf->vb.done)) {
- /* no one active */
- rc = -1;
- goto unlock;
- }
list_del(&buf->vb.queue);
do_gettimeofday(&buf->vb.ts);
dprintk(100, "[%p/%d] wakeup\n", buf, buf->vb.i);
--
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