Re: [PATCH v3 1/4] drm: bridge: dw_hdmi: Add flag to indicate output port is optional
From: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Date: 2024-12-31 20:33:12
Also in:
dri-devel, imx
Hi Marek, Thank you for the patch. On Tue, Dec 31, 2024 at 08:28:48PM +0100, Marek Vasut wrote:
Add a flag meant purely to work around broken i.MX8MP DTs which enable HDMI but do not contain the HDMI connector node. This flag allows such DTs to work by creating the connector in the HDMI bridge driver. Do not use this flag, do not proliferate this flag, please fix your DTs.
What's the rationale for this, what prevents fixing DT instead of using
this flag ? Adding such a flag will most likely open the door to
proliferation.
If you can't fix the DT on particular boards, patching it could be an
option. We had a similar problem on Renesas boards, which we fixed with
a DT overlay, see commit 81c0e3dd82927064 ("drm: rcar-du: Fix legacy DT
to create LVDS encoder nodes"). This made the workaround self-contained,
and allowed dropping it several kernel versions later (in commit
841281fe52a769fe, "drm: rcar-du: Drop LVDS device tree backward
compatibility").
quoted hunk ↗ jump to hunk
Signed-off-by: Marek Vasut <marex@denx.de> --- Cc: Andrzej Hajda <andrzej.hajda@intel.com> Cc: David Airlie <airlied@gmail.com> Cc: Fabio Estevam <festevam@gmail.com> Cc: Jernej Skrabec <jernej.skrabec@gmail.com> Cc: Jonas Karlman <jonas@kwiboo.se> Cc: Laurent Pinchart <Laurent.pinchart@ideasonboard.com> Cc: Liu Ying <victor.liu@nxp.com> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com> Cc: Maxime Ripard <mripard@kernel.org> Cc: Neil Armstrong <neil.armstrong@linaro.org> Cc: Pengutronix Kernel Team <kernel@pengutronix.de> Cc: Robert Foss <rfoss@kernel.org> Cc: Sascha Hauer <s.hauer@pengutronix.de> Cc: Shawn Guo <shawnguo@kernel.org> Cc: Simona Vetter <simona@ffwll.ch> Cc: Stefan Agner <stefan@agner.ch> Cc: Thomas Zimmermann <tzimmermann@suse.de> Cc: dri-devel@lists.freedesktop.org Cc: imx@lists.linux.dev Cc: linux-arm-kernel@lists.infradead.org --- V3: New patch --- drivers/gpu/drm/bridge/synopsys/dw-hdmi.c | 12 ++++++++---- include/drm/bridge/dw_hdmi.h | 2 ++ 2 files changed, 10 insertions(+), 4 deletions(-)diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c index 996733ed2c004..852e73c0f686f 100644 --- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c +++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c@@ -2893,9 +2893,13 @@ static int dw_hdmi_bridge_attach(struct drm_bridge *bridge, { struct dw_hdmi *hdmi = bridge->driver_private; - if (flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR) - return drm_bridge_attach(bridge->encoder, hdmi->next_bridge, - bridge, flags); + if (flags & DRM_BRIDGE_ATTACH_NO_CONNECTOR) { + if (hdmi->plat_data->output_port_optional && !hdmi->next_bridge) + return dw_hdmi_connector_create(hdmi); + else + return drm_bridge_attach(bridge->encoder, hdmi->next_bridge, + bridge, flags); + } return dw_hdmi_connector_create(hdmi); }@@ -3298,7 +3302,7 @@ static int dw_hdmi_parse_dt(struct dw_hdmi *hdmi) hdmi->plat_data->output_port, -1); if (!remote) - return -ENODEV; + return hdmi->plat_data->output_port_optional ? 0 : -ENODEV; hdmi->next_bridge = of_drm_find_bridge(remote); of_node_put(remote);diff --git a/include/drm/bridge/dw_hdmi.h b/include/drm/bridge/dw_hdmi.h index 6a46baa0737cd..3bb6e633424a8 100644 --- a/include/drm/bridge/dw_hdmi.h +++ b/include/drm/bridge/dw_hdmi.h@@ -127,6 +127,8 @@ struct dw_hdmi_plat_data { struct regmap *regm; unsigned int output_port; + /* Used purely by MX8MP HDMI to work around broken DTs without HDMI connector node. */ + bool output_port_optional; unsigned long input_bus_encoding; bool use_drm_infoframe;
-- Regards, Laurent Pinchart