Re: [PATCH 2/3] drm/i915: Use atomic helpers for suspend.

[Maarten Lankhorst <maarten.lankhorst@linux.intel.com>]

Op 09-02-16 om 14:37 schreef Ville Syrjälä:
> On Tue, Feb 09, 2016 at 01:52:22PM +0100, Maarten Lankhorst wrote:
>> Instead of duplicating the functionality now that we no longer need
>> to preserve dpll state we can move to using the upstream suspend helper.
>>
>> Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
>> ---
>>  drivers/gpu/drm/drm_atomic_helper.c  |   3 +
>>  drivers/gpu/drm/i915/i915_drv.c      |   8 ---
>>  drivers/gpu/drm/i915/i915_drv.h      |   1 +
>>  drivers/gpu/drm/i915/intel_display.c | 117 ++++++++++++-----------------------
>>  4 files changed, 42 insertions(+), 87 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
>> index 2b430b05f35d..a2d3b094f27c 100644
>> --- a/drivers/gpu/drm/drm_atomic_helper.c
>> +++ b/drivers/gpu/drm/drm_atomic_helper.c
>> @@ -2102,6 +2102,9 @@ int drm_atomic_helper_resume(struct drm_device *dev,
>>  	err = drm_atomic_commit(state);
>>  	drm_modeset_unlock_all(dev);
>>  
>> +	if (err)
>> +		drm_atomic_state_free(state);
>> +
>>  	return err;
>>  }
>>  EXPORT_SYMBOL(drm_atomic_helper_resume);
>> diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
>> index 11d8414edbbe..fc9b552bfcd1 100644
>> --- a/drivers/gpu/drm/i915/i915_drv.c
>> +++ b/drivers/gpu/drm/i915/i915_drv.c
>> @@ -600,13 +600,7 @@ static int i915_drm_suspend(struct drm_device *dev)
>>  
>>  	intel_suspend_gt_powersave(dev);
>>  
>> -	/*
>> -	 * Disable CRTCs directly since we want to preserve sw state
>> -	 * for _thaw. Also, power gate the CRTC power wells.
>> -	 */
>> -	drm_modeset_lock_all(dev);
>>  	intel_display_suspend(dev);
>> -	drm_modeset_unlock_all(dev);
>>  
>>  	intel_dp_mst_suspend(dev);
>>  
>> @@ -761,9 +755,7 @@ static int i915_drm_resume(struct drm_device *dev)
>>  		dev_priv->display.hpd_irq_setup(dev);
>>  	spin_unlock_irq(&dev_priv->irq_lock);
>>  
>> -	drm_modeset_lock_all(dev);
>>  	intel_display_resume(dev);
>> -	drm_modeset_unlock_all(dev);
>>  
>>  	intel_dp_mst_resume(dev);
>>  
>> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
>> index 8216665405eb..ef289514b97e 100644
>> --- a/drivers/gpu/drm/i915/i915_drv.h
>> +++ b/drivers/gpu/drm/i915/i915_drv.h
>> @@ -1848,6 +1848,7 @@ struct drm_i915_private {
>>  
>>  	enum modeset_restore modeset_restore;
>>  	struct mutex modeset_restore_lock;
>> +	struct drm_atomic_state *modeset_restore_state;
>>  
>>  	struct list_head vm_list; /* Global list of all address spaces */
>>  	struct i915_gtt gtt; /* VM representing the global address space */
>> diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
>> index e496c130364d..4c91fd1c5222 100644
>> --- a/drivers/gpu/drm/i915/intel_display.c
>> +++ b/drivers/gpu/drm/i915/intel_display.c
>> @@ -6393,58 +6393,19 @@ static void intel_crtc_disable_noatomic(struct drm_crtc *crtc)
>>   */
>>  int intel_display_suspend(struct drm_device *dev)
>>  {
>> -	struct drm_mode_config *config = &dev->mode_config;
>> -	struct drm_modeset_acquire_ctx *ctx = config->acquire_ctx;
>> -	struct drm_atomic_state *state;
>> -	struct drm_crtc *crtc;
>> -	unsigned crtc_mask = 0;
>> -	int ret = 0;
>> -
>> -	if (WARN_ON(!ctx))
>> -		return 0;
>> -
>> -	lockdep_assert_held(&ctx->ww_ctx);
>> -	state = drm_atomic_state_alloc(dev);
>> -	if (WARN_ON(!state))
>> -		return -ENOMEM;
>> -
>> -	state->acquire_ctx = ctx;
>> -	state->allow_modeset = true;
>> -
>> -	for_each_crtc(dev, crtc) {
>> -		struct drm_crtc_state *crtc_state =
>> -			drm_atomic_get_crtc_state(state, crtc);
>> -
>> -		ret = PTR_ERR_OR_ZERO(crtc_state);
>> -		if (ret)
>> -			goto free;
>> -
>> -		if (!crtc_state->active)
>> -			continue;
>> -
>> -		crtc_state->active = false;
>> -		crtc_mask |= 1 << drm_crtc_index(crtc);
>> -	}
>> -
>> -	if (crtc_mask) {
>> -		ret = drm_atomic_commit(state);
>> -
>> -		if (!ret) {
>> -			for_each_crtc(dev, crtc)
>> -				if (crtc_mask & (1 << drm_crtc_index(crtc)))
>> -					crtc->state->active = true;
>> -
>> -			return ret;
>> -		}
>> -	}
>> +	struct drm_i915_private *dev_priv = to_i915(dev);
>> +	int ret;
>>  
>> -free:
>> -	if (ret)
>> +	dev_priv->modeset_restore_state = drm_atomic_helper_suspend(dev);
>> +	ret = PTR_ERR_OR_ZERO(dev_priv->modeset_restore_state);
>> +	if (ret) {
>>  		DRM_ERROR("Suspending crtc's failed with %i\n", ret);
>> -	drm_atomic_state_free(state);
>> +		dev_priv->modeset_restore_state = NULL;
>> +	}
> I would use a local state pointer and only assign it to
> modeset_restore_state once we know it's good.
>
>>  	return ret;
>>  }
>>  
>> +
> Spurious newline.
>
>>  void intel_encoder_destroy(struct drm_encoder *encoder)
>>  {
>>  	struct intel_encoder *intel_encoder = to_intel_encoder(encoder);
>> @@ -15909,51 +15870,49 @@ intel_modeset_setup_hw_state(struct drm_device *dev)
>>  
>>  void intel_display_resume(struct drm_device *dev)
>>  {
>> -	struct drm_atomic_state *state = drm_atomic_state_alloc(dev);
>> -	struct intel_connector *conn;
>> -	struct intel_plane *plane;
>> +	struct drm_i915_private *dev_priv = to_i915(dev);
>> +	struct drm_atomic_state *state = dev_priv->modeset_restore_state;
>> +	struct drm_modeset_acquire_ctx ctx;
>>  	struct drm_crtc *crtc;
>> -	int ret;
>> +	struct drm_crtc_state *crtc_state;
>> +	int ret, i;
>> +
>> +	intel_modeset_setup_hw_state(dev);
> Isn't something in there going to scream about locking?
I was hoping to find out by running it through CI..

I don't see what possibly could scream however, from a glance it seems nothing depends on it.
>> +	i915_redisable_vga(dev);
>> +	dev_priv->modeset_restore_state = NULL;
>>  
>>  	if (!state)
>>  		return;
>>  
>> -	state->acquire_ctx = dev->mode_config.acquire_ctx;
>> -
>> -	for_each_crtc(dev, crtc) {
>> -		struct drm_crtc_state *crtc_state =
>> -			drm_atomic_get_crtc_state(state, crtc);
>> -
>> -		ret = PTR_ERR_OR_ZERO(crtc_state);
>> -		if (ret)
>> -			goto err;
>> +	drm_modeset_acquire_init(&ctx, 0);
>> +	state->acquire_ctx = &ctx;
>>  
>> -		/* force a restore */
>> +	for_each_crtc_in_state(state, crtc, crtc_state, i) {
>> +		/*
>> +		 * Force recalculation even if we restore
>> +		 * current state. With fast modeset this may not result
>> +		 * in a modeset when the state is compatible.
>> +		 */
>>  		crtc_state->mode_changed = true;
>>  	}
> Hmm. Why do we need to set that exactly? If the current state doesn't
> match the "to be restored" state, shouldn't something somewhere figure
> out that we really need a modeset?
We have a whole bunch of hw state from suspend that may be different from the hw readout in resume. This is not handled by the core because it doesn't know about driver specific pll's etc. So that's what the mode_changed = true is for. It's a hint to intel_atomic_check that might get downgraded to update_pipe if i915.fastboot is true and the hw readout and resume states are compatible.

~Maarten
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