[igt-dev] [PATCH i-g-t] lib/igt_debugfs: Add timeouts to opening pipe CRC fd.

[Souza, Jose]

On Thu, 2018-04-05 at 22:15 +0100, Chris Wilson wrote:
> Quoting Souza, Jose (2018-04-05 22:03:46)
> > On Thu, 2018-04-05 at 12:49 +0200, Maarten Lankhorst wrote:
> > > This will fix the PSR tests to fail slightly faster, since they
> > > wait
> > > indefinitely for a CRC that never comes during open.
> > > 
> > > Signed-off-by: Maarten Lankhorst <maarten.lankhorst at linux.intel.c
> > > om>
> > > ---
> > >  lib/igt_debugfs.c | 3 +++
> > >  1 file changed, 3 insertions(+)
> > > 
> > > diff --git a/lib/igt_debugfs.c b/lib/igt_debugfs.c
> > > index 8adc02e9cc47..094df564b6f4 100644
> > > --- a/lib/igt_debugfs.c
> > > +++ b/lib/igt_debugfs.c
> > > @@ -757,7 +757,10 @@ void igt_pipe_crc_start(igt_pipe_crc_t
> > > *pipe_crc)
> > >  
> > >       sprintf(buf, "crtc-%d/crc/data", pipe_crc->pipe);
> > >  
> > > +     igt_set_timeout(5, "Opening crc fd, which waits for first
> > > CRC.");
> > >       pipe_crc->crc_fd = openat(pipe_crc->dir, buf, pipe_crc-
> > > > flags);
> > > 
> > > +     igt_reset_timeout();
> > 
> > Hum I was able to reproduce this one too in a KBL, I was thinking
> > in
> > add a timeout in the kernel side, if it don't get the CRC buffer
> > filled
> > it would return a error.
> 
> That would be unexpected behaviour for a read() interface. If you
> want a
> timeout, implement poll().

Not change the read() but return a error in open() when timeout
happens:

"
diff --git a/drivers/gpu/drm/drm_debugfs_crc.c
b/drivers/gpu/drm/drm_debugfs_crc.c
index 9f8312137cad..223cd45b3aff 100644
--- a/drivers/gpu/drm/drm_debugfs_crc.c
+++ b/drivers/gpu/drm/drm_debugfs_crc.c
@@ -206,9 +206,10 @@ static int crtc_crc_open(struct inode *inode,
struct file *filep)
 	 * guess when this particular piece of HW will be ready to
start
 	 * generating CRCs.
 	 */
-	ret = wait_event_interruptible_lock_irq(crc->wq,
-						crtc_crc_data_count(cr
c),
-						crc->lock);
+	ret = wait_event_interruptible_lock_irq_timeout(crc->wq,
+							crtc_crc_data_
count(crc),
+							crc->lock,
+							msecs_to_jiffi
es(2500));
 	spin_unlock_irq(&crc->lock);
 
 	if (ret)
"


> -Chris