On Mon, 24 Mar 2014, Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> wrote:
> On Mon, Mar 24, 2014 at 01:43:38PM +0530, Arun R Murthy wrote:
>> In wait for vblank use usleep_range, which will use hrtimers instead of
>> msleep. Using msleep(1~20) there are more chances of sleeping for 20ms.
>> Using usleep_range uses hrtimers and hence are precise, worst case will
>> trigger an interrupt at the higher/max timeout.
>>
>> Signed-off-by: Arun R Murthy <arun.r.murthy@xxxxxxxxx>
>> ---
>> drivers/gpu/drm/i915/intel_drv.h | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
>> index 44067bc..079280a 100644
>> --- a/drivers/gpu/drm/i915/intel_drv.h
>> +++ b/drivers/gpu/drm/i915/intel_drv.h
>> @@ -52,7 +52,7 @@
>> break; \
>> } \
>> if (W && drm_can_sleep()) { \
>> - msleep(W); \
>> + usleep_range(W * 1000, W * 2 * 1000); \
>> } else { \
>> cpu_relax(); \
>> } \
>
> Ok. But W is still just a random value we picked for being the mininum
> legal value for msleep(). So just usleep_range(500, 2000) or somesuch
> will be fine. We can rename W to CAN_SLEEP it that helps.
We do use _wait_for directly from intel_dp.c with W == 10 to not retry
so many times on what's expected to be a long wait.
BR,
Jani.
> -Chris
>
> --
> Chris Wilson, Intel Open Source Technology Centre
--
Jani Nikula, Intel Open Source Technology Center
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