[Intel-gfx] [PATCH] drm/i915: check to see if SIMD registers are available before using SIMD

Jason A. Donenfeld Jason at zx2c4.com
Sun May 3 20:35:03 UTC 2020

On Sun, May 3, 2020 at 2:30 PM Chris Wilson <chris at chris-wilson.co.uk> wrote:
> Quoting Jason A. Donenfeld (2020-04-30 23:10:16)
> > Sometimes it's not okay to use SIMD registers, the conditions for which
> > have changed subtly from kernel release to kernel release. Usually the
> > pattern is to check for may_use_simd() and then fallback to using
> > something slower in the unlikely case SIMD registers aren't available.
> > So, this patch fixes up i915's accelerated memcpy routines to fallback
> > to boring memcpy if may_use_simd() is false.
> >
> > Cc: stable at vger.kernel.org
> The same argument as on the previous submission is that we return to the
> caller if we can't use movntqda as their fallback path should be faster
> than uncached memcpy.

Oh, THAT's what you meant before. Okay, will follow up.

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