Re: [igt-dev] [RESEND PATCH v6 i-g-t] tests/kms_flip: Skip VBlank tests in modules without VBlank

From: Rodrigo Siqueira <rodrigosiqueiramelo@gmail.com>
To: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Petri Latvala <petri.latvala@intel.com>,
	intel-gfx@lists.freedesktop.org, igt-dev@lists.freedesktop.org
Subject: Re: [igt-dev] [RESEND PATCH v6 i-g-t] tests/kms_flip: Skip VBlank tests in modules without VBlank
Date: Thu, 18 Apr 2019 14:05:18 -0300	[thread overview]
Message-ID: <20190418170518.fsjtvduqvvxrxewg@smtp.gmail.com> (raw)
In-Reply-To: <155560190887.7644.3682179601045366401@skylake-alporthouse-com>

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On 04/18, Chris Wilson wrote:
> Quoting Rodrigo Siqueira (2019-04-18 15:01:49)
> > +bool kms_has_vblank(int fd)
> > +{
> > +       drmVBlank dummy_vbl;
> > +
> > +       memset(&dummy_vbl, 0, sizeof(drmVBlank));
> > +       dummy_vbl.request.type = DRM_VBLANK_RELATIVE;
> > +
> > +       drmWaitVBlank(fd, &dummy_vbl);
> > +       return (errno != EOPNOTSUPP);
> 
> errno is only set on error. It is conceivably that drmWaitVBlank()
> suceeed but errno is still set to EOPNOTSUPP from an earlier syscall.
> -Chris

Nice catch!

Before I send a V7, how about this fix:

bool kms_has_vblank(int fd)
{
  ...
  errno = 0;
  drmWaitVBlank(fd, &dummy_vbl);
  return (errno != EOPNOTSUPP);
}

--
Rodrigo Siqueira
https://siqueira.tech

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