When encoder validation of a display mode fails, retry with less bandwidth
heavy YCbCr420 color mode, if available. This enables some HDMI 1.4 setups
to support 4k60Hz output, which previously failed silently.
AMDGPU had nearly the exact same issue. This problem description is
therefore copied from my commit message of the AMDGPU patch.
On some setups, while the monitor and the gpu support display modes with
pixel clocks of up to 600MHz, the link encoder might not. This prevents
YCbCr444 and RGB encoding for 4k60Hz, but YCbCr420 encoding might still be
possible. However, which color mode is used is decided before the link
encoder capabilities are checked. This patch fixes the problem by retrying
to find a display mode with YCbCr420 enforced and using it, if it is
valid.
This patchset is revision 5. Only change to 4 is a small whitespace error fix.
Couples the decission between RGB and YCbCr420 mode and the check if the port
clock can archive the required frequency. Other checks and configuration steps
that where previously done in between can also be done before or after.
This allows for are cleaner implementation of retrying different color
encodings.
Slight change in behaviour: If YCbCr420 is not allowed but display is YCbCr420
only it no longer fails, but just prints an error and tries to fallback on RGB.
Signed-off-by: Werner Sembach <[email protected]>
---
Imho an error message in when YCbCR420 not allowed meets YCbCr420 only can be
a usefull bugfinding tool for cases of blackscreen on exotic configurations.
I'm unsure if this should be a warning instead.
From 883678ef703b6bb15cd2883eb2c5ce27d07911d3 Mon Sep 17 00:00:00 2001
From: Werner Sembach <[email protected]>
Date: Mon, 3 May 2021 15:30:40 +0200
Subject: [PATCH 2/3] Restructure output format computation for better
expandability
---
drivers/gpu/drm/i915/display/intel_hdmi.c | 65 ++++++++++++-----------
1 file changed, 34 insertions(+), 31 deletions(-)
diff --git a/drivers/gpu/drm/i915/display/intel_hdmi.c b/drivers/gpu/drm/i915/display/intel_hdmi.c
index 576d3d910d06..b0201d4f27eb 100644
--- a/drivers/gpu/drm/i915/display/intel_hdmi.c
+++ b/drivers/gpu/drm/i915/display/intel_hdmi.c
@@ -1999,29 +1999,6 @@ static bool hdmi_deep_color_possible(const struct intel_crtc_state *crtc_state,
INTEL_OUTPUT_FORMAT_YCBCR420);
}
-static int
-intel_hdmi_ycbcr420_config(struct intel_crtc_state *crtc_state,
- const struct drm_connector_state *conn_state)
-{
- struct drm_connector *connector = conn_state->connector;
- struct drm_i915_private *i915 = to_i915(connector->dev);
- const struct drm_display_mode *adjusted_mode =
- &crtc_state->hw.adjusted_mode;
-
- if (!drm_mode_is_420_only(&connector->display_info, adjusted_mode))
- return 0;
-
- if (!connector->ycbcr_420_allowed) {
- drm_err(&i915->drm,
- "Platform doesn't support YCBCR420 output\n");
- return -EINVAL;
- }
-
- crtc_state->output_format = INTEL_OUTPUT_FORMAT_YCBCR420;
-
- return intel_pch_panel_fitting(crtc_state, conn_state);
-}
-
static int intel_hdmi_compute_bpc(struct intel_encoder *encoder,
struct intel_crtc_state *crtc_state,
int clock)
@@ -2128,6 +2105,30 @@ static bool intel_hdmi_has_audio(struct intel_encoder *encoder,
return intel_conn_state->force_audio == HDMI_AUDIO_ON;
}
+static int intel_hdmi_compute_output_format(struct intel_encoder *encoder,
+ struct intel_crtc_state *crtc_state,
+ const struct drm_connector_state *conn_state)
+{
+ struct drm_connector *connector = conn_state->connector;
+ struct drm_i915_private *i915 = to_i915(connector->dev);
+ const struct drm_display_mode *adjusted_mode = &crtc_state->hw.adjusted_mode;
+ int ret;
+ bool ycbcr_420_only;
+
+ ycbcr_420_only = drm_mode_is_420_only(&connector->display_info, adjusted_mode);
+ if (connector->ycbcr_420_allowed && ycbcr_420_only)
+ crtc_state->output_format = INTEL_OUTPUT_FORMAT_YCBCR420;
+ else {
+ if (!connector->ycbcr_420_allowed && ycbcr_420_only)
+ drm_err(&i915->drm, "Display only supports YCbCr420 output, but connector does not allow it. Fallback to RGB, but this will likely fail.\n");
+ crtc_state->output_format = INTEL_OUTPUT_FORMAT_RGB;
+ }
+
+ ret = intel_hdmi_compute_clock(encoder, crtc_state);
+
+ return ret;
+}
+
int intel_hdmi_compute_config(struct intel_encoder *encoder,
struct intel_crtc_state *pipe_config,
struct drm_connector_state *conn_state)
@@ -2152,23 +2153,25 @@ int intel_hdmi_compute_config(struct intel_encoder *encoder,
if (adjusted_mode->flags & DRM_MODE_FLAG_DBLCLK)
pipe_config->pixel_multiplier = 2;
- ret = intel_hdmi_ycbcr420_config(pipe_config, conn_state);
- if (ret)
- return ret;
-
- pipe_config->limited_color_range =
- intel_hdmi_limited_color_range(pipe_config, conn_state);
-
if (HAS_PCH_SPLIT(dev_priv) && !HAS_DDI(dev_priv))
pipe_config->has_pch_encoder = true;
pipe_config->has_audio =
intel_hdmi_has_audio(encoder, pipe_config, conn_state);
- ret = intel_hdmi_compute_clock(encoder, pipe_config);
+ ret = intel_hdmi_compute_output_format(encoder, pipe_config, conn_state);
if (ret)
return ret;
+ if (pipe_config->output_format == INTEL_OUTPUT_FORMAT_YCBCR420) {
+ ret = intel_pch_panel_fitting(pipe_config, conn_state);
+ if (ret)
+ return ret;
+ }
+
+ pipe_config->limited_color_range =
+ intel_hdmi_limited_color_range(pipe_config, conn_state);
+
if (conn_state->picture_aspect_ratio)
adjusted_mode->picture_aspect_ratio =
conn_state->picture_aspect_ratio;
--
2.25.1