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mx.zohomail.com; dkim=pass header.i=collabora.com; spf=pass smtp.mailfrom=nicolas.frattaroli@collabora.com; dmarc=pass header.from= DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; t=1776074941; s=zohomail; d=collabora.com; i=nicolas.frattaroli@collabora.com; h=From:From:Date:Date:Subject:Subject:MIME-Version:Content-Type:Content-Transfer-Encoding:Message-Id:Message-Id:References:In-Reply-To:To:To:Cc:Cc:Reply-To; bh=MC7m65enPeoK56w15mZU/jnX37Exa8SW0qeHJO7INHM=; b=VWjK57pDGc8E9uy/2bjZWIJ0ckYhMtjPQidsS1yNnstKZ8e0ILXtkqasgD/sn1BB I+t6GJWijnGintb3yxBHgMz11cH5fiJnNdTPJLQeLXlA2pLQSVXw6GIGbzQ9fVlVQle f4erS/EcAc3k01XSIv5adacDxy8kLLtlefATEZ70= Received: by mx.zohomail.com with SMTPS id 1776074940799470.07694868646433; Mon, 13 Apr 2026 03:09:00 -0700 (PDT) From: Nicolas Frattaroli Date: Mon, 13 Apr 2026 12:07:23 +0200 Subject: [PATCH v13 09/27] drm/display: hdmi-state-helper: Try subsampling in mode_valid MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260413-color-format-v13-9-ab37d4dfba48@collabora.com> References: <20260413-color-format-v13-0-ab37d4dfba48@collabora.com> In-Reply-To: <20260413-color-format-v13-0-ab37d4dfba48@collabora.com> To: Harry Wentland , Leo Li , Rodrigo Siqueira , Alex Deucher , =?utf-8?q?Christian_K=C3=B6nig?= , David Airlie , Simona Vetter , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , Andrzej Hajda , Neil Armstrong , Robert Foss , Laurent Pinchart , Jonas Karlman , Jernej Skrabec , Sandy Huang , =?utf-8?q?Heiko_St=C3=BCbner?= , Andy Yan , Jani Nikula , Rodrigo Vivi , Joonas Lahtinen , Tvrtko Ursulin , Dmitry Baryshkov , Sascha Hauer , Rob Herring , Jonathan Corbet , Shuah Khan Cc: kernel@collabora.com, amd-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-rockchip@lists.infradead.org, intel-gfx@lists.freedesktop.org, intel-xe@lists.freedesktop.org, linux-doc@vger.kernel.org, Nicolas Frattaroli , Dmitry Baryshkov X-Mailer: b4 0.15.2 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260413_030933_882576_60D2225B X-CRM114-Status: GOOD ( 13.49 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org drm_hdmi_connector_mode_valid assumes modes are only valid if they work with RGB. The reality is more complex however: YCbCr 4:2:0 chroma-subsampled modes only require half the pixel clock that the same mode would require in RGB. This leads to drm_hdmi_connector_mode_valid rejecting perfectly valid 420-only or 420-also modes. Fix this by checking whether the mode is 420-capable first. If so, then proceed by checking it with DRM_OUTPUT_COLOR_FORMAT_YCBCR420 so long as the connector has legalized 420, otherwise error out. If the mode is not 420-capable, check with RGB as was previously always the case. Fixes: 47368ab437fd ("drm/display: hdmi: add generic mode_valid helper") Reviewed-by: Maxime Ripard Reviewed-by: Dmitry Baryshkov Signed-off-by: Nicolas Frattaroli --- drivers/gpu/drm/display/drm_hdmi_state_helper.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/display/drm_hdmi_state_helper.c b/drivers/gpu/drm/display/drm_hdmi_state_helper.c index 954f8b2973fc..5cc30da30989 100644 --- a/drivers/gpu/drm/display/drm_hdmi_state_helper.c +++ b/drivers/gpu/drm/display/drm_hdmi_state_helper.c @@ -942,8 +942,21 @@ drm_hdmi_connector_mode_valid(struct drm_connector *connector, const struct drm_display_mode *mode) { unsigned long long clock; + enum drm_output_color_format fmt; + + if (drm_mode_is_420_only(&connector->display_info, mode)) { + if (connector->ycbcr_420_allowed) + fmt = DRM_OUTPUT_COLOR_FORMAT_YCBCR420; + else + return MODE_NO_420; + } else if (drm_mode_is_420_also(&connector->display_info, mode) && + connector->ycbcr_420_allowed) { + fmt = DRM_OUTPUT_COLOR_FORMAT_YCBCR420; + } else { + fmt = DRM_OUTPUT_COLOR_FORMAT_RGB444; + } - clock = drm_hdmi_compute_mode_clock(mode, 8, DRM_OUTPUT_COLOR_FORMAT_RGB444); + clock = drm_hdmi_compute_mode_clock(mode, 8, fmt); if (!clock) return MODE_ERROR; -- 2.53.0