Re: [PATCH v2 3/6] drm/i915/psr: Make intel_psr_set_debugfs_mode() only handle PSR mode

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Op 04-01-2019 om 14:28 schreef Souza, Jose:
> On Fri, 2019-01-04 at 07:53 +0100, Maarten Lankhorst wrote:
>> Op 03-01-2019 om 15:21 schreef José Roberto de Souza:
>>> intel_psr_set_debugfs_mode() don't just handle the PSR mode but it
>>> is
>>> also handling input validation, setting the new debug value and
>>> changing PSR IRQ masks.
>>> Lets move the roles listed above to the caller to make the function
>>> name and what it does accurate.
>>>
>>> Cc: Dhinakaran Pandiyan <dhinakaran.pandiyan@xxxxxxxxx>
>>> Cc: Rodrigo Vivi <rodrigo.vivi@xxxxxxxxx>
>>> Cc: Maarten Lankhorst <maarten.lankhorst@xxxxxxxxxxxxxxx>
>>> Signed-off-by: José Roberto de Souza <jose.souza@xxxxxxxxx>
>>> ---
>>>  drivers/gpu/drm/i915/i915_debugfs.c | 22 ++++++++++++++++++++--
>>>  drivers/gpu/drm/i915/intel_drv.h    |  2 +-
>>>  drivers/gpu/drm/i915/intel_psr.c    | 26 ++++++++++---------------
>>> -
>>>  3 files changed, 31 insertions(+), 19 deletions(-)
>>>
>>> diff --git a/drivers/gpu/drm/i915/i915_debugfs.c
>>> b/drivers/gpu/drm/i915/i915_debugfs.c
>>> index 1a31921598e7..77b097b50fd5 100644
>>> --- a/drivers/gpu/drm/i915/i915_debugfs.c
>>> +++ b/drivers/gpu/drm/i915/i915_debugfs.c
>>> @@ -2639,19 +2639,29 @@ i915_edp_psr_debug_set(void *data, u64 val)
>>>  {
>>>  	struct drm_i915_private *dev_priv = data;
>>>  	struct drm_modeset_acquire_ctx ctx;
>>> -	int ret;
>>> +	const u32 mode = val & I915_PSR_DEBUG_MODE_MASK;
>>> +	int ret = 0;
>>>  
>>>  	if (!CAN_PSR(dev_priv))
>>>  		return -ENODEV;
>>>  
>>>  	DRM_DEBUG_KMS("Setting PSR debug to %llx\n", val);
>>>  
>>> +	if (val & ~(I915_PSR_DEBUG_IRQ | I915_PSR_DEBUG_MODE_MASK) ||
>>> +	    mode > I915_PSR_DEBUG_FORCE_PSR1) {
>>> +		DRM_DEBUG_KMS("Invalid debug mask %llx\n", val);
>>> +		return -EINVAL;
>>> +	}
>> This would only work for (psr.debug & MASK) == (val & MASK).
>>
>> So you need to take the lock before you can be sure.
>>
>> While at it, you probably also need the intel_runtime_pm_get()
>> reference.. so you really don't complicate locking much.
>>
>> I would honestly just grab the extra locks unnecessarily for
>> simplicity. It's only used from debugfs after all.
> Thanks for the catch.
>
> Something like this?
>
> diff --git a/drivers/gpu/drm/i915/i915_debugfs.c
> b/drivers/gpu/drm/i915/i915_debugfs.c
> index 938ad2107ead..3a6ccf815ee1 100644
> --- a/drivers/gpu/drm/i915/i915_debugfs.c
> +++ b/drivers/gpu/drm/i915/i915_debugfs.c
> @@ -2656,11 +2656,13 @@ i915_edp_psr_debug_set(void *data, u64 val)
>                 return -EINVAL;
>         }
>
> -       if (!mode)
> -               goto skip_mode;
> -
>         intel_runtime_pm_get(dev_priv);
>
> +       mutex_lock(&dev_priv->psr.lock);
> +       if (mode == (dev_priv->psr.debug & I915_PSR_DEBUG_MODE_MASK))
> +               goto skip_mode;
> +       mutex_unlock(&dev_priv->psr.lock);
> +
>         drm_modeset_acquire_init(&ctx,
> DRM_MODESET_ACQUIRE_INTERRUPTIBLE);
>
>  retry:
> @@ -2674,8 +2676,6 @@ i915_edp_psr_debug_set(void *data, u64 val)
>         drm_modeset_drop_locks(&ctx);
>         drm_modeset_acquire_fini(&ctx);
>
> -       intel_runtime_pm_put(dev_priv);
> -
>  skip_mode:
>         if (!ret) {
>                 mutex_lock(&dev_priv->psr.lock);
> @@ -2684,6 +2684,8 @@ i915_edp_psr_debug_set(void *data, u64 val)
>                 mutex_unlock(&dev_priv->psr.lock);
>         }
>
> +       intel_runtime_pm_put(dev_priv);
> +
>         return ret;
>  }
>
>
>
>
>>> +
>>> +	if (!mode)
>>> +		goto skip_mode;
>>> +
>>>  	intel_runtime_pm_get(dev_priv);
>>>  
>>>  	drm_modeset_acquire_init(&ctx,
>>> DRM_MODESET_ACQUIRE_INTERRUPTIBLE);
>>>  
>>>  retry:
>>> -	ret = intel_psr_set_debugfs_mode(dev_priv, &ctx, val);
>>> +	ret = intel_psr_set_debugfs_mode(dev_priv, &ctx, mode);
>>>  	if (ret == -EDEADLK) {
>>>  		ret = drm_modeset_backoff(&ctx);
>>>  		if (!ret)
>>> @@ -2663,6 +2673,14 @@ i915_edp_psr_debug_set(void *data, u64 val)
>>>  
>>>  	intel_runtime_pm_put(dev_priv);
>>>  
>>> +skip_mode:
>>> +	if (!ret) {
>>> +		mutex_lock(&dev_priv->psr.lock);
>>> +		dev_priv->psr.debug = val;
>>> +		intel_psr_irq_control(dev_priv, dev_priv->psr.debug);
>>> +		mutex_unlock(&dev_priv->psr.lock);
>>> +	}
>>> +
>>>  	return ret;
>>>  }
>>>  
>>> diff --git a/drivers/gpu/drm/i915/intel_drv.h
>>> b/drivers/gpu/drm/i915/intel_drv.h
>>> index 1a11c2beb7f3..2367f07ba29e 100644
>>> --- a/drivers/gpu/drm/i915/intel_drv.h
>>> +++ b/drivers/gpu/drm/i915/intel_drv.h
>>> @@ -2063,7 +2063,7 @@ void intel_psr_disable(struct intel_dp
>>> *intel_dp,
>>>  		      const struct intel_crtc_state *old_crtc_state);
>>>  int intel_psr_set_debugfs_mode(struct drm_i915_private *dev_priv,
>>>  			       struct drm_modeset_acquire_ctx *ctx,
>>> -			       u64 value);
>>> +			       u32 mode);
>>>  void intel_psr_invalidate(struct drm_i915_private *dev_priv,
>>>  			  unsigned frontbuffer_bits,
>>>  			  enum fb_op_origin origin);
>>> diff --git a/drivers/gpu/drm/i915/intel_psr.c
>>> b/drivers/gpu/drm/i915/intel_psr.c
>>> index 0ef6c5f8c298..bba4f7da68b3 100644
>>> --- a/drivers/gpu/drm/i915/intel_psr.c
>>> +++ b/drivers/gpu/drm/i915/intel_psr.c
>>> @@ -69,13 +69,14 @@ static bool psr_global_enabled(u32 debug)
>>>  }
>>>  
>>>  static bool intel_psr2_enabled(struct drm_i915_private *dev_priv,
>>> -			       const struct intel_crtc_state
>>> *crtc_state)
>>> +			       const struct intel_crtc_state
>>> *crtc_state,
>>> +			       u32 debug)
>>>  {
>>>  	/* Cannot enable DSC and PSR2 simultaneously */
>>>  	WARN_ON(crtc_state->dsc_params.compression_enable &&
>>>  		crtc_state->has_psr2);
>>>  
>>> -	switch (dev_priv->psr.debug & I915_PSR_DEBUG_MODE_MASK) {
>>> +	switch (debug & I915_PSR_DEBUG_MODE_MASK) {
>>>  	case I915_PSR_DEBUG_DISABLE:
>>>  	case I915_PSR_DEBUG_FORCE_PSR1:
>>>  		return false;
>>> @@ -758,7 +759,8 @@ void intel_psr_enable(struct intel_dp
>>> *intel_dp,
>>>  		goto unlock;
>>>  	}
>>>  
>>> -	dev_priv->psr.psr2_enabled = intel_psr2_enabled(dev_priv,
>>> crtc_state);
>>> +	dev_priv->psr.psr2_enabled = intel_psr2_enabled(dev_priv,
>>> crtc_state,
>>> +							dev_priv-
>>>> psr.debug);
>>>  	dev_priv->psr.busy_frontbuffer_bits = 0;
>>>  	dev_priv->psr.prepared = true;
>>>  	dev_priv->psr.pipe = to_intel_crtc(crtc_state->base.crtc)-
>>>> pipe;
>>> @@ -944,7 +946,7 @@ static bool switching_psr(struct
>>> drm_i915_private *dev_priv,
>>>  
>>>  int intel_psr_set_debugfs_mode(struct drm_i915_private *dev_priv,
>>>  			       struct drm_modeset_acquire_ctx *ctx,
>>> -			       u64 val)
>>> +			       u32 mode)
>>>  {
>>>  	struct drm_device *dev = &dev_priv->drm;
>>>  	struct drm_connector_state *conn_state;
>>> @@ -954,13 +956,6 @@ int intel_psr_set_debugfs_mode(struct
>>> drm_i915_private *dev_priv,
>>>  	struct intel_dp *dp;
>>>  	int ret;
>>>  	bool enable;
>>> -	u32 mode = val & I915_PSR_DEBUG_MODE_MASK;
>>> -
>>> -	if (val & ~(I915_PSR_DEBUG_IRQ | I915_PSR_DEBUG_MODE_MASK) ||
>>> -	    mode > I915_PSR_DEBUG_FORCE_PSR1) {
>>> -		DRM_DEBUG_KMS("Invalid debug mask %llx\n", val);
>>> -		return -EINVAL;
>>> -	}
>>>  
>>>  	ret = drm_modeset_lock(&dev->mode_config.connection_mutex,
>>> ctx);
>>>  	if (ret)
>>> @@ -990,16 +985,15 @@ int intel_psr_set_debugfs_mode(struct
>>> drm_i915_private *dev_priv,
>>>  	if (ret)
>>>  		return ret;
>>>  
>>> -	enable = psr_global_enabled(val);
>>> +	enable = psr_global_enabled(mode);
>>>  
>>>  	if (!enable || switching_psr(dev_priv, crtc_state, mode))
>>>  		intel_psr_disable_locked(dev_priv->psr.dp);
>>>  
>>> -	dev_priv->psr.debug = val;
>>>  	if (crtc)
>>> -		dev_priv->psr.psr2_enabled =
>>> intel_psr2_enabled(dev_priv, crtc_state);
>>> -
>>> -	intel_psr_irq_control(dev_priv, dev_priv->psr.debug);
>>> +		dev_priv->psr.psr2_enabled =
>>> intel_psr2_enabled(dev_priv,
>>> +								crtc_st
>>> ate,
>>> +								mode);
>>>  
>>>  	if (dev_priv->psr.prepared && enable)
>>>  		intel_psr_enable_locked(dev_priv, crtc_state);
>>
Hm I would change the psr irq inside the lock, then jump to pm_put to finish and call that label out. Most race-free way to do so. :)

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