Re: [PATCH v2 4/6] drm/i915/guc: remove writes to GEN8_DRBREG registers

[Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>]

On 10/06/16 17:50, Dave Gordon wrote:
> These registers are not actually writable by the CPU; only the GuC can
> actually program them. So let's not do writes that have no effect.
>
> Signed-off-by: Dave Gordon <david.s.gordon@intel.com>
> ---
>   drivers/gpu/drm/i915/i915_guc_submission.c | 5 -----
>   1 file changed, 5 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_guc_submission.c b/drivers/gpu/drm/i915/i915_guc_submission.c
> index e198599..45b33f8 100644
> --- a/drivers/gpu/drm/i915/i915_guc_submission.c
> +++ b/drivers/gpu/drm/i915/i915_guc_submission.c
> @@ -197,14 +197,9 @@ static void guc_disable_doorbell(struct intel_guc *guc,
>
>   	doorbell->db_status = GUC_DOORBELL_DISABLED;
>
> -	I915_WRITE(drbreg, I915_READ(drbreg) & ~GEN8_DRB_VALID);
> -
>   	value = I915_READ(drbreg);
>   	WARN_ON((value & GEN8_DRB_VALID) != 0);
>
> -	I915_WRITE(GEN8_DRBREGU(client->doorbell_id), 0);
> -	I915_WRITE(drbreg, 0);
> -
>   	/* XXX: wait for any interrupts */
>   	/* XXX: wait for workqueue to drain */
>   }
>

I have to trust you on this one. :)

Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>

Regards,

Tvrtko
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