[Intel-gfx] [PATCH v2 2/6] drm/i915/psr: Always wait for idle state when disabling PSR

[Dhinakaran Pandiyan]

On Wednesday, October 10, 2018 5:41:20 PM PDT José Roberto de Souza wrote:
> It should always wait for idle state when disabling PSR because PSR
> could be inactive due a call to intel_psr_exit() and while PSR is
> still being disabled asynchronously userspace could change the
> modeset causing a call to psr_disable() that will not wait for PSR
> idle and then PSR will be enabled again while PSR is still not idle.
> 
> v2: rebased on top of the patch reusing psr_exit()
> 
> Cc: Rodrigo Vivi <rodrigo.vivi at intel.com>
> Cc: Dhinakaran Pandiyan <dhinakaran.pandiyan at intel.com>
> Signed-off-by: José Roberto de Souza <jose.souza at intel.com>
> ---
>  drivers/gpu/drm/i915/intel_psr.c | 41 ++++++++++++++------------------
>  1 file changed, 18 insertions(+), 23 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/intel_psr.c
> b/drivers/gpu/drm/i915/intel_psr.c index f698b3f45c6d..16d0e3df7de0 100644
> --- a/drivers/gpu/drm/i915/intel_psr.c
> +++ b/drivers/gpu/drm/i915/intel_psr.c
> @@ -661,8 +661,12 @@ static void intel_psr_exit(struct drm_i915_private
> *dev_priv) {
>  	u32 val;
> 
> -	if (!dev_priv->psr.active)
> +	if (!dev_priv->psr.active) {
> +		if (INTEL_GEN(dev_priv) >= 9)
> +			WARN_ON(I915_READ(EDP_PSR2_CTL) & EDP_PSR2_ENABLE);
> +		WARN_ON(I915_READ(EDP_PSR_CTL) & EDP_PSR_ENABLE);

Do we really need so many WARN_ONs needing MMIO reads? There are almost as 
many lines of warnings as code in this function. I think at this point, we 
know this code works and the warnings in psr_exit() should be removed.

>  		return;
> +	}
> 
>  	if (dev_priv->psr.psr2_enabled) {
>  		val = I915_READ(EDP_PSR2_CTL);
> @@ -680,32 +684,23 @@ static void
>  intel_psr_disable_source(struct intel_dp *intel_dp)
>  {
>  	struct drm_i915_private *dev_priv = dp_to_i915(intel_dp);
> +	i915_reg_t psr_status;
> +	u32 psr_status_mask;
> 
> -	if (dev_priv->psr.active) {
> -		i915_reg_t psr_status;
> -		u32 psr_status_mask;
> -
> -		intel_psr_exit(dev_priv);
> +	intel_psr_exit(dev_priv);
> 
> -		if (dev_priv->psr.psr2_enabled) {
> -			psr_status = EDP_PSR2_STATUS;
> -			psr_status_mask = EDP_PSR2_STATUS_STATE_MASK;
> -		} else {
> -			psr_status = EDP_PSR_STATUS;
> -			psr_status_mask = EDP_PSR_STATUS_STATE_MASK;
> -		}
> -
> -		/* Wait till PSR is idle */
> -		if (intel_wait_for_register(dev_priv,
> -					    psr_status, psr_status_mask, 0,
> -					    2000))
> -			DRM_ERROR("Timed out waiting for PSR Idle State\n");
> +	if (dev_priv->psr.psr2_enabled) {
> +		psr_status = EDP_PSR2_STATUS;
> +		psr_status_mask = EDP_PSR2_STATUS_STATE_MASK;
>  	} else {
> -		if (dev_priv->psr.psr2_enabled)
> -			WARN_ON(I915_READ(EDP_PSR2_CTL) & EDP_PSR2_ENABLE);
> -		else
> -			WARN_ON(I915_READ(EDP_PSR_CTL) & EDP_PSR_ENABLE);
> +		psr_status = EDP_PSR_STATUS;
> +		psr_status_mask = EDP_PSR_STATUS_STATE_MASK;
>  	}
> +
> +	/* Wait till PSR is idle */
> +	if (intel_wait_for_register(dev_priv, psr_status, psr_status_mask, 0,
> +				    2000))
> +		DRM_ERROR("Timed out waiting for PSR Idle State\n");
>  }
> 
>  static void intel_psr_disable_locked(struct intel_dp *intel_dp)