Re: [igt-dev] [PATCH i-g-t 4/4] lib/igt_fb: Generalize the slow read from gtt mmap handling

From: "Ville Syrjälä" <ville.syrjala@linux.intel.com>
To: Chris Wilson <chris@chris-wilson.co.uk>
Cc: igt-dev@lists.freedesktop.org
Subject: Re: [igt-dev] [PATCH i-g-t 4/4] lib/igt_fb: Generalize the slow read from gtt mmap handling
Date: Fri, 2 Nov 2018 21:37:14 +0200	[thread overview]
Message-ID: <20181102193714.GE9144@intel.com> (raw)
In-Reply-To: <154118712205.30246.6540566950532000022@skylake-alporthouse-com>

On Fri, Nov 02, 2018 at 07:32:02PM +0000, Chris Wilson wrote:
> Quoting Ville Syrjälä (2018-11-02 19:30:29)
> > On Fri, Nov 02, 2018 at 07:17:03PM +0000, Chris Wilson wrote:
> > > Quoting Ville Syrjala (2018-11-02 19:06:51)
> > > > +static void *convert_src_get(const struct fb_convert *cvt)
> > > > +{
> > > > +       void *buf;
> > > > +
> > > > +       if (!cvt->src.slow_reads)
> > > > +               return cvt->src.ptr;
> > > > +
> > > > +       /*
> > > > +        * Reading from the BO is awfully slow because of lack of read caching,
> > > > +        * it's faster to copy the whole BO to a temporary buffer and convert
> > > > +        * from there.
> > > > +        */
> > > > +       buf = malloc(cvt->src.fb->size);
> > > 
> > > if (!buf)
> > >       return cvt->src.ptr;
> > 
> > Sure, why not.
> 
> The other choice being igt_assert(buf) or igt_xmalloc() :)

I figured the NULL ptr explosion is as good as an assert. But
since it's trivial to handle it gracefully let's do that.

-- 
Ville Syrjälä
Intel
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