[Intel-gfx] [PATCH 2/2] drm/i915: Set adjustment to zero on Up/Down interrupts if freq is already max/min

Chris Wilson chris at chris-wilson.co.uk
Fri Jan 20 09:35:44 UTC 2017

On Fri, Jan 20, 2017 at 09:18:24AM +0530, Sagar Arun Kamble wrote:
> When we reach the user's RPS limits, stop requesting an adjustment. Even
> though we will clamp the requested frequency later, we rely on interrupt
> masking to disable further adjustments in the same direction. Even
> though it is unlikely (one scenario is a bug in the driver, another is
> careful manipulation through the uAPI) if we keep exponentially
> increasing the adjustment value, it will wrap and cause a negative
> adjustment.
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Reviewed-by: Sagar Arun Kamble <sagar.a.kamble at intel.com>

Grabbed this one because I know it is safe. There's some underlying
trouble fouling guc so judging results for patch 1 is tricky. A single
run suggests that all guc machines are affected by an unrecoverable
hang following that patch - but the same issue seems present without the
patch just on isolated machines.

Chris Wilson, Intel Open Source Technology Centre

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