Re: [PATCH v2 1/3] drm/bridge: imx8mp-hdmi-tx: switch to bridge DRM_BRIDGE_ATTACH_NO_CONNECTOR

[Marek Vasut <marex@denx.de>]

On 12/24/24 5:21 AM, Dmitry Baryshkov wrote:
> On Tue, Dec 24, 2024 at 02:46:14AM +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")
>>
>> 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
>> ---
>>   drivers/gpu/drm/bridge/imx/Kconfig          | 1 +
>>   drivers/gpu/drm/bridge/imx/imx8mp-hdmi-tx.c | 1 +
>>   2 files changed, 2 insertions(+)
>>
>> diff --git a/drivers/gpu/drm/bridge/imx/Kconfig b/drivers/gpu/drm/bridge/imx/Kconfig
>> index 9a480c6abb856..d8e9fbf75edbb 100644
>> --- a/drivers/gpu/drm/bridge/imx/Kconfig
>> +++ b/drivers/gpu/drm/bridge/imx/Kconfig
>> @@ -27,6 +27,7 @@ config DRM_IMX8MP_DW_HDMI_BRIDGE
>>   config DRM_IMX8MP_HDMI_PVI
>>   	tristate "Freescale i.MX8MP HDMI PVI bridge support"
>>   	depends on OF
>> +	select DRM_DISPLAY_CONNECTOR
>>   	help
>>   	  Choose this to enable support for the internal HDMI TX Parallel
>>   	  Video Interface found on the Freescale i.MX8MP SoC.
>> diff --git a/drivers/gpu/drm/bridge/imx/imx8mp-hdmi-tx.c b/drivers/gpu/drm/bridge/imx/imx8mp-hdmi-tx.c
>> index 1e7a789ec2890..4ebae5ad072ad 100644
>> --- a/drivers/gpu/drm/bridge/imx/imx8mp-hdmi-tx.c
>> +++ b/drivers/gpu/drm/bridge/imx/imx8mp-hdmi-tx.c
>> @@ -101,6 +101,7 @@ static int imx8mp_dw_hdmi_probe(struct platform_device *pdev)
>>   	plat_data->phy_name = "SAMSUNG HDMI TX PHY";
>>   	plat_data->priv_data = hdmi;
>>   	plat_data->phy_force_vendor = true;
>> +	plat_data->output_port = 1;
> 
> Quoting my feedback to a similar Liu's patch:
> 
> This will break compatibility with older DT files, which don't have
> output port. I think you need to add output_port_optional flag to
> dw_hdmi_plat_data and still return 0 from dw_hdmi_parse_dt() if the flag
> is set, but there is no remote node.
Looking at the upstream 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. Every follow up addition 
of HDMI to another device has been a copy of the same commit, with 
connector, so I think it is safe to say, no upstream DT is going to be 
broken by this change. Do we care about hypothetical downstream DTs 
which may be missing the connector ?