Re: [v3 3/5] drm/bridge: add psr support during panel bridge enable & disable sequence

[Dmitry Baryshkov <dmitry.baryshkov@linaro.org>]

On 21/06/2022 13:53, Vinod Polimera wrote:
> This change avoids panel prepare/unprepare based on self-refresh
> state.
> 
> Signed-off-by: Sankeerth Billakanti <quic_sbillaka@quicinc.com>
> Signed-off-by: Kalyan Thota <quic_kalyant@quicinc.com>
> Signed-off-by: Vinod Polimera <quic_vpolimer@quicinc.com>
> ---
>   drivers/gpu/drm/bridge/panel.c | 102 +++++++++++++++++++++++++++++++++++++++--
>   1 file changed, 98 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/gpu/drm/bridge/panel.c b/drivers/gpu/drm/bridge/panel.c
> index 59a3496..6b09ae0 100644
> --- a/drivers/gpu/drm/bridge/panel.c
> +++ b/drivers/gpu/drm/bridge/panel.c
> @@ -41,6 +41,40 @@ static int panel_bridge_connector_get_modes(struct drm_connector *connector)
>   	return drm_panel_get_modes(panel_bridge->panel, connector);
>   }
>   
> +static struct drm_crtc *bridge_drm_get_old_connector_crtc(struct drm_encoder *encoder,
> +							struct drm_atomic_state *state)
> +{
> +	struct drm_connector *connector;
> +	struct drm_connector_state *conn_state;
> +
> +	connector = drm_atomic_get_old_connector_for_encoder(state, encoder);
> +	if (!connector)
> +		return NULL;
> +
> +	conn_state = drm_atomic_get_old_connector_state(state, connector);
> +	if (!conn_state)
> +		return NULL;
> +
> +	return conn_state->crtc;
> +}
> +
> +static struct drm_crtc *bridge_drm_get_new_connector_crtc(struct drm_encoder *encoder,
> +							struct drm_atomic_state *state)
> +{
> +	struct drm_connector *connector;
> +	struct drm_connector_state *conn_state;
> +
> +	connector = drm_atomic_get_new_connector_for_encoder(state, encoder);
> +	if (!connector)
> +		return NULL;
> +
> +	conn_state = drm_atomic_get_new_connector_state(state, connector);
> +	if (!conn_state)
> +		return NULL;
> +
> +	return conn_state->crtc;
> +}

As I wrote earlier, this should become generic drm helpers.

> +
>   static const struct drm_connector_helper_funcs
>   panel_bridge_connector_helper_funcs = {
>   	.get_modes = panel_bridge_connector_get_modes,
> @@ -108,30 +142,90 @@ static void panel_bridge_detach(struct drm_bridge *bridge)
>   		drm_connector_cleanup(connector);
>   }
>   
> -static void panel_bridge_atomic_pre_enable(struct drm_bridge *bridge)
> +static void panel_bridge_atomic_pre_enable(struct drm_bridge *bridge,
> +					struct drm_bridge_state *old_bridge_state)

This must be a part of the previous patch?

>   {
>   	struct panel_bridge *panel_bridge = drm_bridge_to_panel_bridge(bridge);
> +	struct drm_atomic_state *old_state = old_bridge_state->base.state;
> +	struct drm_encoder *encoder = bridge->encoder;
> +	struct drm_crtc *crtc;
> +	struct drm_crtc_state *old_crtc_state;
> +
> +	crtc = bridge_drm_get_new_connector_crtc(encoder, old_state);
> +	if (!crtc)
> +		return;

Why? And why do you ask for the new crtc from the old state?

> +
> +	old_crtc_state = drm_atomic_get_old_crtc_state(old_state, crtc);
> +
> +	/* Don't touch the panel if we're coming back from self refresh state */
> +	if (old_crtc_state && old_crtc_state->self_refresh_active)
> +		return;
>   
>   	drm_panel_prepare(panel_bridge->panel);
>   }
>   
> -static void panel_bridge_atomic_enable(struct drm_bridge *bridge)
> +static void panel_bridge_atomic_enable(struct drm_bridge *bridge,
> +					struct drm_bridge_state *old_bridge_state)
>   {
>   	struct panel_bridge *panel_bridge = drm_bridge_to_panel_bridge(bridge);
> +	struct drm_atomic_state *old_state = old_bridge_state->base.state;
> +	struct drm_encoder *encoder = bridge->encoder;
> +	struct drm_crtc *crtc;
> +	struct drm_crtc_state *old_crtc_state;
> +
> +	crtc = bridge_drm_get_new_connector_crtc(encoder, old_state);
> +	if (!crtc)
> +		return;
> +
> +	old_crtc_state = drm_atomic_get_old_crtc_state(old_state, crtc);
> +
> +	/* Don't touch the panel if we're coming back from self refresh state */
> +	if (old_crtc_state && old_crtc_state->self_refresh_active)
> +		return;
>   
>   	drm_panel_enable(panel_bridge->panel);
>   }
>   
> -static void panel_bridge_atomic_disable(struct drm_bridge *bridge)
> +static void panel_bridge_atomic_disable(struct drm_bridge *bridge,
> +					struct drm_bridge_state *old_bridge_state)
>   {
>   	struct panel_bridge *panel_bridge = drm_bridge_to_panel_bridge(bridge);
> +	struct drm_atomic_state *old_state = old_bridge_state->base.state;
> +	struct drm_encoder *encoder = bridge->encoder;
> +	struct drm_crtc *crtc;
> +	struct drm_crtc_state *new_crtc_state;
> +
> +	crtc = bridge_drm_get_old_connector_crtc(encoder, old_state);
> +	if (!crtc)
> +		return;
> +
> +	new_crtc_state = drm_atomic_get_new_crtc_state(old_state, crtc);

This doesn't sound right too.

> +
> +	/* Don't do a full disable on PSR transitions if new state is self refresh state */
> +	if (new_crtc_state && new_crtc_state->self_refresh_active)
> +		return;
>   
>   	drm_panel_disable(panel_bridge->panel);
>   }
>   
> -static void panel_bridge_atomic_post_disable(struct drm_bridge *bridge)
> +static void panel_bridge_atomic_post_disable(struct drm_bridge *bridge,
> +					struct drm_bridge_state *old_bridge_state)
>   {
>   	struct panel_bridge *panel_bridge = drm_bridge_to_panel_bridge(bridge);
> +	struct drm_atomic_state *old_state = old_bridge_state->base.state;
> +	struct drm_encoder *encoder = bridge->encoder;
> +	struct drm_crtc *crtc;
> +	struct drm_crtc_state *new_crtc_state;
> +
> +	crtc = bridge_drm_get_old_connector_crtc(encoder, old_state);
> +	if (!crtc)
> +		return;
> +
> +	new_crtc_state = drm_atomic_get_new_crtc_state(old_state, crtc);
> +
> +	/* Don't do unprepare on PSR transitions if new state is self refresh state */
> +	if (new_crtc_state && new_crtc_state->self_refresh_active)
> +		return;
>   
>   	drm_panel_unprepare(panel_bridge->panel);
>   }


-- 
With best wishes
Dmitry