Re: [PATCH i-g-t 1/2] tests/kms_setmode: Request the intiial vbl count with RELATIVE instead of ABSOLUTE

From: "Ville Syrjälä" <ville.syrjala@linux.intel.com>
To: Daniel Vetter <daniel@ffwll.ch>
Cc: intel-gfx@lists.freedesktop.org
Subject: Re: [PATCH i-g-t 1/2] tests/kms_setmode: Request the intiial vbl count with RELATIVE instead of ABSOLUTE
Date: Tue, 10 Oct 2017 12:24:06 +0300	[thread overview]
Message-ID: <20171010092406.GO10981@intel.com> (raw)
In-Reply-To: <20171010091623.di56pedxk4xtxwsy@phenom.ffwll.local>

On Tue, Oct 10, 2017 at 11:16:23AM +0200, Daniel Vetter wrote:
> On Mon, Oct 09, 2017 at 07:33:49PM +0300, Ville Syrjala wrote:
> > From: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > 
> > Asking for the initial vblank count by specifying and absolute vblank count of 0
> > doesn't make much sense. Switch to a relative query instead.
> > 
> > Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> > ---
> >  tests/kms_setmode.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/tests/kms_setmode.c b/tests/kms_setmode.c
> > index 206d360607bb..ed5d97442255 100644
> > --- a/tests/kms_setmode.c
> > +++ b/tests/kms_setmode.c
> > @@ -431,7 +431,7 @@ static void check_timings(int crtc_idx, const drmModeModeInfo *kmode)
> >  
> >  	memset(&wait, 0, sizeof(wait));
> >  	wait.request.type = kmstest_get_vbl_flag(crtc_idx);
> > -	wait.request.type |= DRM_VBLANK_ABSOLUTE | DRM_VBLANK_NEXTONMISS;
> > +	wait.request.type |= DRM_VBLANK_RELATIVE | DRM_VBLANK_NEXTONMISS;
> 
> Looking at drm_wait_vblank_is_query() in drm_vblank.c you also want to
> drop NEXTONMISS.

Hmm. I think we may want to line things up to a vblank boundary here
(but I'd have to re-read the code to confirm that). Without the
NEXTONMISS we would just query the current count and continue
immediately. Alternative I guess we could drop the NEXTONMISS but
instead wait for seq+1.

> With that:
> 
> Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch> on both.
> 
> Cheers, Daniel
> >  	do_or_die(drmWaitVBlank(drm_fd, &wait));
> >  
> >  	last_seq = wait.reply.sequence;
> > -- 
> > 2.13.5
> > 
> > _______________________________________________
> > Intel-gfx mailing list
> > Intel-gfx@lists.freedesktop.org
> > https://lists.freedesktop.org/mailman/listinfo/intel-gfx
> 
> -- 
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch

-- 
Ville Syrjälä
Intel OTC
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