2014-09-24 19:16 GMT-03:00 Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>:
> Let's make sure PSR is propperly disabled before to re-enabled it.
>
> According to Spec, after disabled PSR CTL, the Idle state might occur
> up to 24ms, that is one full frame time (1/refresh rate),
> plus SRD exit training time (max of 6ms),
> plus SRD aux channel handshake (max of 1.5ms).
>
> So if something went wrong PSR will be disabled until next full
> enable/disable setup.
>
> v2: The 24ms above takes in account 16ms for refresh rate on 60Hz mode. However
> on low frequency modes this can take longer. So let's use 50ms for safeness.
>
> v3: Move wait out of psr.lock critical area.
>
> Cc: Daniel Vetter <daniel.vetter@xxxxxxxx>
> Cc: Paulo Zanoni <paulo.r.zanoni@xxxxxxxxx>
> Signed-off-by: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
Again, since we already waited for 100ms while queueing
intel_edp_psr_work, an additional 50ms is basically useless. I'd
really like this function to just have an I915_READ instead of yet
another wait, so any necessary wait-time-tuning would be part of the
schedule_delayed_work(dev_priv->psr.work) call.
That said, the current patch is already an improvement, so:
Reviewed-by: Paulo Zanoni <paulo.r.zanoni@xxxxxxxxx>
But I'd prefer the solution I proposed :)
> ---
> drivers/gpu/drm/i915/intel_dp.c | 11 +++++++++++
> 1 file changed, 11 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c
> index a119b9b..b8699b0 100644
> --- a/drivers/gpu/drm/i915/intel_dp.c
> +++ b/drivers/gpu/drm/i915/intel_dp.c
> @@ -2208,6 +2208,17 @@ static void intel_edp_psr_work(struct work_struct *work)
> container_of(work, typeof(*dev_priv), psr.work.work);
> struct intel_dp *intel_dp = dev_priv->psr.enabled;
>
> + /* We have to make sure PSR is ready for re-enable
> + * otherwise it keeps disabled until next full enable/disable cycle.
> + * PSR might take some time to get fully disabled
> + * and be ready for re-enable.
> + */
> + if (wait_for((I915_READ(EDP_PSR_STATUS_CTL(dev_priv->dev)) &
> + EDP_PSR_STATUS_STATE_MASK) == 0, 50)) {
> + DRM_ERROR("Timed out waiting for PSR Idle for re-enable\n");
> + return;
> + }
> +
> mutex_lock(&dev_priv->psr.lock);
> intel_dp = dev_priv->psr.enabled;
>
> --
> 1.9.3
>
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--
Paulo Zanoni
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