From 388b863509f76f6a5ecedd7ffdaf184aa813241e Mon Sep 17 00:00:00 2001 From: Werner Sembach Date: Mon, 10 May 2021 15:33:49 +0200 Subject: [PATCH] drm/i915/display: Use YCbCr420 as fallback when RGB fails MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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. Signed-off-by: Werner Sembach Signed-off-by: Ville Syrjälä Link: https://patchwork.freedesktop.org/patch/msgid/20210510133349.14491-4-wse@tuxedocomputers.com --- drivers/gpu/drm/i915/display/intel_hdmi.c | 25 ++++++++++++++++++++++--- 1 file changed, 22 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/i915/display/intel_hdmi.c b/drivers/gpu/drm/i915/display/intel_hdmi.c index 79ebb58..98da94a 100644 --- a/drivers/gpu/drm/i915/display/intel_hdmi.c +++ b/drivers/gpu/drm/i915/display/intel_hdmi.c @@ -1900,6 +1900,7 @@ intel_hdmi_mode_valid(struct drm_connector *connector, int clock = mode->clock; int max_dotclk = to_i915(connector->dev)->max_dotclk_freq; bool has_hdmi_sink = intel_has_hdmi_sink(hdmi, connector->state); + bool ycbcr_420_only; if (mode->flags & DRM_MODE_FLAG_DBLSCAN) return MODE_NO_DBLESCAN; @@ -1916,12 +1917,22 @@ intel_hdmi_mode_valid(struct drm_connector *connector, clock *= 2; } - if (drm_mode_is_420_only(&connector->display_info, mode)) + ycbcr_420_only = drm_mode_is_420_only(&connector->display_info, mode); + if (ycbcr_420_only) clock /= 2; status = intel_hdmi_mode_clock_valid(hdmi, clock, has_hdmi_sink); - if (status != MODE_OK) - return status; + if (status != MODE_OK) { + if (ycbcr_420_only || + !connector->ycbcr_420_allowed || + !drm_mode_is_420_also(&connector->display_info, mode)) + return status; + + clock /= 2; + status = intel_hdmi_mode_clock_valid(hdmi, clock, has_hdmi_sink); + if (status != MODE_OK) + return status; + } return intel_mode_valid_max_plane_size(dev_priv, mode, false); } @@ -2129,6 +2140,14 @@ static int intel_hdmi_compute_output_format(struct intel_encoder *encoder, } ret = intel_hdmi_compute_clock(encoder, crtc_state); + if (ret) { + if (crtc_state->output_format != INTEL_OUTPUT_FORMAT_YCBCR420 && + connector->ycbcr_420_allowed && + drm_mode_is_420_also(&connector->display_info, adjusted_mode)) { + crtc_state->output_format = INTEL_OUTPUT_FORMAT_YCBCR420; + ret = intel_hdmi_compute_clock(encoder, crtc_state); + } + } return ret; } -- 2.7.4