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

Chris Wilson chris at chris-wilson.co.uk
Sun May 3 20:20:19 UTC 2020

Quoting Christoph Hellwig (2020-05-01 19:07:31)
> On Thu, Apr 30, 2020 at 04:10:16PM -0600, Jason A. Donenfeld wrote:
> > 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.
> Err, why does i915 implements its own uncached memcpy instead of relying
> on core functionality to start with?

What is this core functionality that provides movntqda?

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