On Fri, Apr 07, 2017 at 01:32:12PM +0000, Michal Wajdeczko wrote:
> Waiting for the response status in scratch register can be done
> using our generic function that waits for the expected register
> state. Since completion of the GuC commands can take longer than
> 2us mark that wait as bit slower to extend atomic wait to 10us.
>
> Signed-off-by: Michal Wajdeczko <michal.wajdeczko@xxxxxxxxx>
> Suggested-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
> Cc: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx>
> Cc: Joonas Lahtinen <joonas.lahtinen@xxxxxxxxxxxxxxx>
> Cc: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
> ---
> drivers/gpu/drm/i915/intel_uc.c | 27 ++++++++-------------------
> 1 file changed, 8 insertions(+), 19 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_uc.c b/drivers/gpu/drm/i915/intel_uc.c
> index c117424..432b540 100644
> --- a/drivers/gpu/drm/i915/intel_uc.c
> +++ b/drivers/gpu/drm/i915/intel_uc.c
> @@ -360,19 +360,6 @@ void intel_uc_fini_hw(struct drm_i915_private *dev_priv)
> }
>
> /*
> - * Read GuC command/status register (SOFT_SCRATCH_0)
> - * Return true if it contains a response rather than a command
> - */
> -static bool guc_recv(struct intel_guc *guc, u32 *status)
> -{
> - struct drm_i915_private *dev_priv = guc_to_i915(guc);
> -
> - u32 val = I915_READ(SOFT_SCRATCH(0));
> - *status = val;
> - return INTEL_GUC_RECV_IS_RESPONSE(val);
> -}
> -
> -/*
> * This function implements the MMIO based host to GuC interface.
> */
> int intel_guc_send_mmio(struct intel_guc *guc, const u32 *action, u32 len)
> @@ -399,13 +386,15 @@ int intel_guc_send_mmio(struct intel_guc *guc, const u32 *action, u32 len)
> I915_WRITE(GUC_SEND_INTERRUPT, GUC_SEND_TRIGGER);
>
> /*
> - * Fast commands should complete in less than 10us, so sample quickly
> - * up to that length of time, then switch to a slower sleep-wait loop.
> - * No inte_guc_send command should ever take longer than 10ms.
> + * No GuC command should ever take longer than 10ms.
> + * Fast commands should still complete in 10us.
> */
> - ret = wait_for_us(guc_recv(guc, &status), 10);
> - if (ret)
> - ret = wait_for(guc_recv(guc, &status), 10);
> + ret = intel_wait_for_register_fw(dev_priv,
> + SOFT_SCRATCH(0),
> + INTEL_GUC_RECV_MASK,
> + INTEL_GUC_RECV_MASK,
> + false, 10);
> + status = I915_READ(SOFT_SCRATCH(0));
Reporting the final register value is common -- I think most of the
remaining wait_for_us() holdouts are because they wanted to interpret
the value after the loop. I wonder if adding an out param for the value
to wait_for_register would cover the remaining missing users?
-Chris
--
Chris Wilson, Intel Open Source Technology Centre
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