Re: [PATCH v2 3/3] drm/rockchip: dw_dp: Attach "max bpc" connector property

From: Igor Paunovic <royalnet026@gmail.com>
To: Chaoyi Chen <chaoyi.chen@rock-chips.com>,
	Maxime Ripard <mripard@kernel.org>,
	Cristian Ciocaltea <cristian.ciocaltea@collabora.com>
Cc: Igor Paunovic <royalnet026@gmail.com>,
	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,
	Dmitry Baryshkov <dmitry.baryshkov@oss.qualcomm.com>,
	Laurent Pinchart <Laurent.pinchart@ideasonboard.com>,
	Andrzej Hajda <andrzej.hajda@intel.com>,
	Neil Armstrong <neil.armstrong@linaro.org>,
	Robert Foss <rfoss@kernel.org>, Jonas Karlman <jonas@kwiboo.se>,
	Jernej Skrabec <jernej.skrabec@gmail.com>,
	Luca Ceresoli <luca.ceresoli@bootlin.com>,
	Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
	Thomas Zimmermann <tzimmermann@suse.de>,
	David Airlie <airlied@gmail.com>, Simona Vetter <simona@ffwll.ch>,
	Sandy Huang <hjc@rock-chips.com>,
	Heiko Stuebner <heiko@sntech.de>,
	Andy Yan <andy.yan@rock-chips.com>,
	Sebastian Reichel <sebastian.reichel@collabora.com>,
	Jani Nikula <jani.nikula@linux.intel.com>,
	Rodrigo Vivi <rodrigo.vivi@intel.com>,
	Ville Syrjala <ville.syrjala@linux.intel.com>,
	Imre Deak <imre.deak@intel.com>,
	Ankit Nautiyal <ankit.k.nautiyal@intel.com>
Subject: Re: [PATCH v2 3/3] drm/rockchip: dw_dp: Attach "max bpc" connector property
Date: Thu, 10 Sep 2026 14:04:06 +0200	[thread overview]
Message-ID: <20260910120409.63850-1-royalnet026@gmail.com> (raw)
In-Reply-To: <388fd1ef-a8c9-4419-8bf2-10af7063e734@rock-chips.com>

Hi Chaoyi,

On 9/10/26 10:16, Chaoyi Chen wrote:
> Maybe we should consider adding a new "DRM_BRIDGE_OP_DP" :)

Works for me - it keeps the HDMI-only wording of max_bpc and makes the
check explicit. So that Maxime and Cristian have something concrete to
object to, this is all I would give the flag:

 - DRM_BRIDGE_OP_DP: the bridge drives a DisplayPort connector and
   fills in max_bpc. Nothing else is read from it for now.
 - drm_bridge_connector_init() treats it like DRM_BRIDGE_OP_HDMI:
   at most one such bridge in the chain (-EBUSY), max_bpc must be set
   (-EINVAL), and the connector gets "max bpc" with range 6..max_bpc.
 - dw-dp sets the flag and max_bpc = 10.

The connector itself stays a plain drmm_connector_init() one - no DP
counterpart of drmm_connector_hdmi_init() - so bridges without the flag
see no change at all.

> Perhaps @Cristian and @Maxime have better ideas?

That is point 3, and I will wait for it before writing v3: whether the
create-state block gets duplicated into the non-HDMI path or factored
out of drmm_connector_hdmi_init(), and whether keeping the restore value
in struct drm_bridge_connector is acceptable once 71/74 lands.

Thanks,
Igor