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[2001:4c4e:1b91:4600:1c92:980e:e711:98ab]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-49d20fce7a7sm251593715e9.4.2026.09.10.00.51.58 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 10 Sep 2026 00:52:00 -0700 (PDT) From: Igor Paunovic To: Chaoyi Chen Cc: Igor Paunovic , dri-devel@lists.freedesktop.org, linux-rockchip@lists.infradead.org, intel-gfx@lists.freedesktop.org, intel-xe@lists.freedesktop.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Maxime Ripard , Dmitry Baryshkov , Laurent Pinchart , Andrzej Hajda , Neil Armstrong , Robert Foss , Jonas Karlman , Jernej Skrabec , Luca Ceresoli , Maarten Lankhorst , Thomas Zimmermann , David Airlie , Simona Vetter , Sandy Huang , Heiko Stuebner , Andy Yan , Sebastian Reichel , Cristian Ciocaltea , Jani Nikula , Rodrigo Vivi , Ville Syrjala , Imre Deak , Ankit Nautiyal Subject: Re: [PATCH v2 3/3] drm/rockchip: dw_dp: Attach "max bpc" connector property Date: Thu, 10 Sep 2026 09:51:40 +0200 Message-ID: <20260910075141.48803-1-royalnet026@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <9e77b5c5-f1d9-484b-ae02-846fae1b3642@rock-chips.com> References: <9e77b5c5-f1d9-484b-ae02-846fae1b3642@rock-chips.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260910_005203_291288_E16E1A63 X-CRM114-Status: GOOD ( 19.07 ) 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 Hi Chaoyi, On 9/10/26 09:16, Chaoyi Chen wrote: > I don't think this is the correct way to go. > > I believe max_bpc should be handled in drm_bridge_connector_init(). > Take a look at its implementation. HDMI already does max_bpc there, > so DP should probably do something similar. Agreed - that is the question I left open in my reply to the bot. v3 moves it into drm_bridge_connector_init() and drops this glue patch. Three points I would rather ask than guess, since it is shared code: 1. How the bridge advertises it. drm_bridge.max_bpc is documented as "only relevant if DRM_BRIDGE_OP_HDMI is set" and the helper only reads it inside the OP_HDMI block. I intend to honour it on the non-HDMI path too, relax that doc sentence, and have dw-dp set bridge->max_bpc = 10. If you prefer to keep the field HDMI-only, a separate field is easy - I just did not want to add one unasked. 2. The range. HDMI attaches 8..max_bpc. dw-dp's format table goes down to 6 bpc RGB and i915 attaches 6..N on its DP connectors, so I intend 6..max_bpc when connector_type is DisplayPort, 8..max_bpc otherwise - the same gate Dmitry used for the DP subconnector property in his msm series [1]. Nothing is attached unless a bridge declared max_bpc, so existing non-HDMI bridge connectors are unchanged. 3. Where the default lives. 2/3 restores max_requested_bpc from connector->max_bpc after drm_mode_config_reset(), but Cristian's v11 71/74 removes that field [2] (HDMI keeps it in hdmi.funcs). I intend to keep the value in struct drm_bridge_connector and restore it from there in drm_bridge_connector_create_state(), which folds 2/3 into the same patch. 1/3 is unaffected. The state still has to exist before the property is attached, so the non-HDMI path gets the same create-state block drmm_connector_hdmi_init() has. If you would rather see that block factored into a helper for both callers, say so and I will do that instead. [1] https://lore.kernel.org/all/20260722-drm-msm-display-interface-v1-24-368c10fe62fd@oss.qualcomm.com/ [2] https://lore.kernel.org/all/20260901-dw-hdmi-qp-scramb-v11-71-bc12954a0688@collabora.com/ Thanks, Igor