Commit 899f9d7b authored by Ville Syrjälä's avatar Ville Syrjälä
Browse files

drm/i915: Readout conn_state->max_bpc 



Populate conn_state->max_bpc with something sensible from the start.
Otherwise it's possible that we get to compute_sink_pipe_bpp() with
max_bpc==0.

The specific scenario goes as follows:
1. Initial connector state allocated with max_bpc==0
2. Trigger a modeset on the crtc feeding the connector, without
   actually adding the connector to the commit
3. drm_atomic_connector_check() is skipped because the
   connector has not yet been added, hence conn_state->max_bpc
   retains its current value
4. drm_atomic_helper_check_modeset() ->
   drm_atomic_add_affected_connectors() -> the connector
   is now part of the commit
5. compute_baseline_pipe_bpp() -> MISSING_CASE(max_bpc==0)

Note that pipe_bpp itself may not be populated on pre-g4x machines,
in which case we just fall back to max_bpc==8 and let .compute_config()
limit the resulting pipe_bpp further if necessary.

Cc: Daniel Vetter <daniel@ffwll.ch>
Reported-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: default avatarVille Syrjälä <ville.syrjala@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210216160035.4780-1-ville.syrjala@linux.intel.com


Tested-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: default avatarJosé Roberto de Souza <jose.souza@intel.com>
parent cec3295b

drivers/gpu/drm/i915/display/intel_display.c

+16 −8
Original line number Diff line number Diff line
@@ -7991,19 +7991,27 @@ static void intel_modeset_update_connector_atomic_state(struct drm_device *dev) 


	drm_connector_list_iter_begin(dev, &conn_iter);

	for_each_intel_connector_iter(connector, &conn_iter) {

		if (connector->base.state->crtc)

		struct drm_connector_state *conn_state = connector->base.state;

		struct intel_encoder *encoder =

			to_intel_encoder(connector->base.encoder);



		if (conn_state->crtc)

			drm_connector_put(&connector->base);



		if (connector->base.encoder) {

			connector->base.state->best_encoder =

				connector->base.encoder;

			connector->base.state->crtc =

				connector->base.encoder->crtc;

		if (encoder) {

			struct intel_crtc *crtc =

				to_intel_crtc(encoder->base.crtc);

			const struct intel_crtc_state *crtc_state =

				to_intel_crtc_state(crtc->base.state);



			conn_state->best_encoder = &encoder->base;

			conn_state->crtc = &crtc->base;

			conn_state->max_bpc = (crtc_state->pipe_bpp ?: 24) / 3;



			drm_connector_get(&connector->base);

		} else {

			connector->base.state->best_encoder = NULL;

			connector->base.state->crtc = NULL;

			conn_state->best_encoder = NULL;

			conn_state->crtc = NULL;

		}

	}

	drm_connector_list_iter_end(&conn_iter);