Re: [PATCH 4/5] drm: Use mode_valid() in atomic modeset

[Ville Syrjälä]

On Thu, May 04, 2017 at 03:11:41PM +0100, Jose Abreu wrote:
> This patches makes use of the new mode_valid() callbacks introduced
> previously to validate the full video pipeline when modesetting.
> 
> This calls the connector->mode_valid(), encoder->mode_valid(),
> bridge->mode_valid() and crtc->mode_valid() so that we can
> make sure that the mode will be accepted in every components.
> 
> Signed-off-by: Jose Abreu <joabreu@xxxxxxxxxxxx>
> Cc: Carlos Palminha <palminha@xxxxxxxxxxxx>
> Cc: Alexey Brodkin <abrodkin@xxxxxxxxxxxx>
> Cc: Ville Syrjälä <ville.syrjala@xxxxxxxxxxxxxxx>
> Cc: Daniel Vetter <daniel.vetter@xxxxxxxx>
> Cc: Dave Airlie <airlied@xxxxxxxx>
> Cc: Andrzej Hajda <a.hajda@xxxxxxxxxxx>
> Cc: Archit Taneja <architt@xxxxxxxxxxxxxx>
> ---
>  drivers/gpu/drm/drm_atomic_helper.c | 92 +++++++++++++++++++++++++++++++++++--
>  1 file changed, 89 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_atomic_helper.c b/drivers/gpu/drm/drm_atomic_helper.c
> index 8be9719..6eb305d 100644
> --- a/drivers/gpu/drm/drm_atomic_helper.c
> +++ b/drivers/gpu/drm/drm_atomic_helper.c
> @@ -452,6 +452,85 @@ static int handle_conflicting_encoders(struct drm_atomic_state *state,
>  	return 0;
>  }
>  
> +static enum drm_mode_status mode_valid_pipe(struct drm_connector *connector,

The name feels off. Pipe means crtc for i915, and for drm_irq.c as well.

> +					    struct drm_encoder *encoder,
> +					    struct drm_crtc *crtc,
> +					    struct drm_display_mode *mode)
> +{
> +	const struct drm_crtc_helper_funcs *crtc_funcs = crtc->helper_private;
> +	const struct drm_connector_helper_funcs *connector_funcs =
> +		connector->helper_private;
> +	const struct drm_encoder_helper_funcs *encoder_funcs =
> +		encoder->helper_private;
> +	enum drm_mode_status ret = MODE_OK;
> +
> +	if (connector_funcs && connector_funcs->mode_valid)
> +		ret = connector_funcs->mode_valid(connector, mode);

As I mentioned earlier, this would break i915. We either can't call the 
connector hook at all here, or we have to make it somehow opt-in if some
drivers really want to do it.

> +
> +	if (ret != MODE_OK) {
> +		DRM_DEBUG_ATOMIC("[CONNECTOR:%d:%s] mode_valid() failed\n",
> +				connector->base.id, connector->name);
> +		return ret;
> +	}
> +
> +	if (encoder_funcs && encoder_funcs->mode_valid)
> +		ret = encoder_funcs->mode_valid(encoder, mode);
> +
> +	if (ret != MODE_OK) {
> +		DRM_DEBUG_ATOMIC("[ENCODER:%d:%s] mode_valid() failed\n",
> +				encoder->base.id, encoder->name);
> +		return ret;
> +	}
> +
> +	ret = drm_bridge_mode_valid(encoder->bridge, mode);
> +	if (ret != MODE_OK) {
> +		DRM_DEBUG_ATOMIC("[BRIDGE] mode_valid() failed\n");
> +		return ret;
> +	}
> +
> +	if (crtc_funcs && crtc_funcs->mode_valid)
> +		ret = crtc_funcs->mode_valid(crtc, mode);
> +
> +	if (ret != MODE_OK) {
> +		DRM_DEBUG_ATOMIC("[CRTC:%d:%s] mode_valid() failed\n",
> +				crtc->base.id, crtc->name);
> +		return ret;
> +	}
> +
> +	return ret;
> +}
> +
> +static int
> +mode_valid(struct drm_atomic_state *state)
> +{
> +	struct drm_connector_state *conn_state;
> +	struct drm_connector *connector;
> +	int i;
> +
> +	for_each_connector_in_state(state, connector, conn_state, i) {

for_each_new...

> +		struct drm_encoder *encoder = conn_state->best_encoder;
> +		struct drm_crtc *crtc = conn_state->crtc;
> +		struct drm_crtc_state *crtc_state;
> +		enum drm_mode_status mode_status;
> +		struct drm_display_mode *mode;
> +
> +		if (!crtc || !encoder)
> +			continue;
> +
> +		crtc_state = drm_atomic_get_new_crtc_state(state, crtc);
> +		if (!crtc_state)
> +			continue;


Maybe?

if (!mode_changed && !connectors_changed)
	continue;

> +
> +		mode = &crtc_state->mode;

Seems like a fairly pointless variable.

> +
> +		mode_status = mode_valid_pipe(connector, encoder, crtc, mode);
> +		if (mode_status != MODE_OK)
> +			return -EINVAL;
> +	}
> +
> +	return 0;
> +}
> +
>  /**
>   * drm_atomic_helper_check_modeset - validate state object for modeset changes
>   * @dev: DRM device
> @@ -466,13 +545,16 @@ static int handle_conflicting_encoders(struct drm_atomic_state *state,
>   * 2. &drm_connector_helper_funcs.atomic_check to validate the connector state.
>   * 3. If it's determined a modeset is needed then all connectors on the affected crtc
>   *    crtc are added and &drm_connector_helper_funcs.atomic_check is run on them.
> - * 4. &drm_bridge_funcs.mode_fixup is called on all encoder bridges.
> - * 5. &drm_encoder_helper_funcs.atomic_check is called to validate any encoder state.
> + * 4. &drm_connector_helper_funcs.mode_valid, &drm_encoder_helper_funcs.mode_valid,
> + *    &drm_bridge_funcs.mode_valid and &drm_crtc_helper_funcs.mode_valid are called
> + *    on the affected components.
> + * 5. &drm_bridge_funcs.mode_fixup is called on all encoder bridges.
> + * 6. &drm_encoder_helper_funcs.atomic_check is called to validate any encoder state.
>   *    This function is only called when the encoder will be part of a configured crtc,
>   *    it must not be used for implementing connector property validation.
>   *    If this function is NULL, &drm_atomic_encoder_helper_funcs.mode_fixup is called
>   *    instead.
> - * 6. &drm_crtc_helper_funcs.mode_fixup is called last, to fix up the mode with crtc constraints.
> + * 7. &drm_crtc_helper_funcs.mode_fixup is called last, to fix up the mode with crtc constraints.
>   *
>   * &drm_crtc_state.mode_changed is set when the input mode is changed.
>   * &drm_crtc_state.connectors_changed is set when a connector is added or
> @@ -617,6 +699,10 @@ static int handle_conflicting_encoders(struct drm_atomic_state *state,
>  			return ret;
>  	}
>  
> +	ret = mode_valid(state);
> +	if (ret)
> +		return ret;
> +
>  	return mode_fixup(state);
>  }
>  EXPORT_SYMBOL(drm_atomic_helper_check_modeset);
> -- 
> 1.9.1
> 

-- 
Ville Syrjälä
Intel OTC