Re: [PATCH 4/5] drm/i915/guc: Increase wait timeout for doorbell release status update

[Sagar Arun Kamble <sagar.a.kamble@intel.com>]

On 11/5/2017 9:25 PM, Michal Wajdeczko wrote:
> On Sun, 05 Nov 2017 14:39:42 +0100, Sagar Arun Kamble 
> <sagar.a.kamble@intel.com> wrote:
>
>> Current wait timeout of 10us is very tight as seen on SKL/KBL randomly
>> for pm_rpm@basic-pci-d3-state. Increase it to 50us.
>>
>> Signed-off-by: Sagar Arun Kamble <sagar.a.kamble@intel.com>
>> Cc: Chris Wilson <chris@chris-wilson.co.uk>
>> Cc: Michał Winiarski <michal.winiarski@intel.com>
>> Cc: Michel Thierry <michel.thierry@intel.com>
>> Cc: Michal Wajdeczko <michal.wajdeczko@intel.com>
>> Cc: Arkadiusz Hiler <arkadiusz.hiler@intel.com>
>> Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
>> ---
>>  drivers/gpu/drm/i915/i915_guc_submission.c | 3 ++-
>>  1 file changed, 2 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpu/drm/i915/i915_guc_submission.c 
>> b/drivers/gpu/drm/i915/i915_guc_submission.c
>> index 21f7fa7..3914415 100644
>> --- a/drivers/gpu/drm/i915/i915_guc_submission.c
>> +++ b/drivers/gpu/drm/i915/i915_guc_submission.c
>> @@ -222,7 +222,8 @@ static int __destroy_doorbell(struct 
>> i915_guc_client *client, bool notify_guc)
>>      /* Doorbell release flow requires that we wait for 
>> GEN8_DRB_VALID bit
>>       * to go to zero after updating db_status before we call the GuC to
>>       * release the doorbell */
>> -    if (wait_for_us(!(I915_READ(GEN8_DRBREGL(db_id)) & 
>> GEN8_DRB_VALID), 10))
>> +    if (wait_for_us(!(I915_READ(GEN8_DRBREGL(db_id)) & GEN8_DRB_VALID),
>> +            50))
>
> Can we use intel_wait_for_register() here ?
Yes. Since wait timeout is expected to be in the order of uS (50us for 
now) will be using __intel_wait_for_register_fw.

+        if (__intel_wait_for_register_fw(dev_priv, GEN8_DRBREGL(db_id), 
GEN8_DRB_VALID, 0,
+ 50, 1, NULL))

Is this fine (with slow timeout of 1ms)?

>>          WARN_ONCE(true, "Doorbell never became invalid after 
>> disable\n");
>>     if (notify_guc)

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