Re: [PATCH v3 2/4] drm/bridge: imx8mp-hdmi-tx: switch to bridge DRM_BRIDGE_ATTACH_NO_CONNECTOR

[Marek Vasut <marex@denx.de>]

On 1/2/25 5:55 AM, Dmitry Baryshkov wrote:
> On Tue, Dec 31, 2024 at 08:28:49PM +0100, Marek Vasut wrote:
>> The dw-hdmi output_port is set to 1 in order to look for a connector
>> next bridge in order to get DRM_BRIDGE_ATTACH_NO_CONNECTOR working.
>> The output_port set to 1 makes the DW HDMI driver core look up the
>> next bridge in DT, where the next bridge is often the hdmi-connector .
>>
>> Similar to 0af5e0b41110 ("drm/meson: encoder_hdmi: switch to bridge DRM_BRIDGE_ATTACH_NO_CONNECTOR")
>>
>> Note that looking at the upstream arch/arm64/boot/dts/freescale/imx8mp*dts ,
>> the oldest commit which adds HDMI support is commit:
>>
>> 3e67a1ddd56d ("arm64: dts: imx8mp: Enable HDMI on TQMa8MPxL/MBa8MPxL")
>>
>> That already contains the HDMI connector node. Most follow up additions
>> of HDMI support to another devices has been a variation of the same commit,
>> including connector node, which is the proper way of eanbling HDMI on the
>> i.MX8MP.
>>
>> The rest should be covered by output_port_optional which should make systems
>> with DTs without HDMI connector node work, but such DTs should be updated and
>> the HDMI connector node should be added.
>>
>> 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
>> ---
>> V2: No change
>> V3: - Update commit message
>>      - Move select DRM_DISPLAY_CONNECTOR to DRM_IMX8MP_DW_HDMI_BRIDGE
>>      - Enable output_port_optional
>> ---
>>   drivers/gpu/drm/bridge/imx/Kconfig          | 1 +
>>   drivers/gpu/drm/bridge/imx/imx8mp-hdmi-tx.c | 2 ++
>>   2 files changed, 3 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/bridge/imx/Kconfig b/drivers/gpu/drm/bridge/imx/Kconfig
>> index 9a480c6abb856..db5c8a76193ac 100644
>> --- a/drivers/gpu/drm/bridge/imx/Kconfig
>> +++ b/drivers/gpu/drm/bridge/imx/Kconfig
>> @@ -17,6 +17,7 @@ config DRM_IMX8MP_DW_HDMI_BRIDGE
>>   	tristate "Freescale i.MX8MP HDMI-TX bridge support"
>>   	depends on OF
>>   	depends on COMMON_CLK
>> +	select DRM_DISPLAY_CONNECTOR
> 
> I was going to write that it is not to be selected by anybody, but then
> I stumbled upon meson driver, which also selects the symbol.
> 
> I still think that it is not to be selected by your driver as there is
> no direct dependency (and there can be other bridges inbetween or the
> bridge chain can end up with some other bridge). Such decisions belong
> to defconfig or distribution's kernel config file.
Wouldn't that only lead to unnecessary surprises on user side ?