Messages in this thread | | | Date | Fri, 1 May 2020 12:42:15 +0200 | From | Sebastian Andrzej Siewior <> | Subject | Re: [PATCH] drm/i915: check to see if SIMD registers are available before using SIMD |
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On 2020-04-30 16:10:16 [-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.
That would indicate that these functions are used from IRQ/softirq which break otherwise if the kernel is also using the registers. The crypto code uses it for that purpose.
So Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
May I ask how large the memcpy can be? I'm asking in case it is large and an explicit rescheduling point might be needed.
> Cc: stable@vger.kernel.org > Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Sebastian
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