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

[Marek Vasut <marex@denx.de>]

On 12/30/24 8:04 AM, Ying Liu wrote:
> On 12/26/2024, Marek Vasut wrote:
>> 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 ?
> 
> These have no HDMI connector nodes:
> arch/arm64/boot/dts/freescale/imx8mp-aristainetos3a-som-v1.dtsi
> arch/arm64/boot/dts/freescale/imx8mp-kontron-bl-osm-s.dts
> arch/arm64/boot/dts/freescale/imx8mp-kontron-smarc-eval-carrier.dts
> arch/arm64/boot/dts/freescale/imx8mp-msc-sm2s-ep1.dts
Huh, I missed those, thanks.

Would it be OK with you to fix those DTs up and add the missing 
connector, rather than introduce some optional port workaround for them ?