From c94cd0620a922156c9ff9af9c3301b174b287677 Mon Sep 17 00:00:00 2001 From: Dom Cobley Date: Mon, 13 Jun 2022 16:47:58 +0200 Subject: [PATCH] drm/vc4: hdmi: Force modeset when bpc or format changes Whenever the maximum BPC is changed, vc4_hdmi_encoder_compute_config() might pick up a different BPC or format depending on the display capabilities. That change will have a number of side effects, including the clock rates and whether the scrambling is enabled. However, only drm_crtc_state.connectors_changed will be set to true, since that properly only affects the connector. This means that while drm_atomic_crtc_needs_modeset() will return true, and thus drm_atomic_helper_commit_modeset_enables() will call our encoder atomic_enable() hook, mode_changed will be false. So crtc_set_mode() will not call our encoder .atomic_mode_set() hook. We use this hook in vc4 to set the vc4_hdmi_connector_state.output_bpc (and output_format), and will then reuse the value in .atomic_enable() to select whether or not scrambling should be enabled. However, since our clock rate is pre-computed during .atomic_check(), we end up with the clocks properly configured, but the scrambling disabled, leading to a blank screen. Let's set mode_changed to true in our HDMI driver to force the update of output_bpc, and thus prevent the issue entirely. Fixes: ba8c0faebbb0 ("drm/vc4: hdmi: Enable 10/12 bpc output") Signed-off-by: Dom Cobley Link: https://lore.kernel.org/r/20220613144800.326124-32-maxime@cerno.tech Signed-off-by: Maxime Ripard --- drivers/gpu/drm/vc4/vc4_hdmi.c | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/vc4/vc4_hdmi.c b/drivers/gpu/drm/vc4/vc4_hdmi.c index 6f71310..c1714a3 100644 --- a/drivers/gpu/drm/vc4/vc4_hdmi.c +++ b/drivers/gpu/drm/vc4/vc4_hdmi.c @@ -1605,9 +1605,14 @@ static int vc4_hdmi_encoder_atomic_check(struct drm_encoder *encoder, struct drm_crtc_state *crtc_state, struct drm_connector_state *conn_state) { + struct vc4_hdmi *vc4_hdmi = encoder_to_vc4_hdmi(encoder); + struct drm_connector *connector = &vc4_hdmi->connector; + struct drm_connector_state *old_conn_state = + drm_atomic_get_old_connector_state(conn_state->state, connector); + struct vc4_hdmi_connector_state *old_vc4_state = + conn_state_to_vc4_hdmi_conn_state(old_conn_state); struct vc4_hdmi_connector_state *vc4_state = conn_state_to_vc4_hdmi_conn_state(conn_state); struct drm_display_mode *mode = &crtc_state->adjusted_mode; - struct vc4_hdmi *vc4_hdmi = encoder_to_vc4_hdmi(encoder); unsigned long long tmds_char_rate = mode->clock * 1000; unsigned long long tmds_bit_rate; int ret; @@ -1636,6 +1641,11 @@ static int vc4_hdmi_encoder_atomic_check(struct drm_encoder *encoder, if (ret) return ret; + /* vc4_hdmi_encoder_compute_config may have changed output_bpc and/or output_format */ + if (vc4_state->output_bpc != old_vc4_state->output_bpc || + vc4_state->output_format != old_vc4_state->output_format) + crtc_state->mode_changed = true; + return 0; } -- 2.7.4