linux-kernel - Re: [PATCH 4/5] drm/bridge: imx8mp-hdmi-tx: Set output

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Message-ID: <vvsj6ri2ke25nzocbq736yv7rphzma6pn3yk2uh7iu43zfe2sa@2fwye4k4w6he>
Date: Fri, 18 Oct 2024 15:31:20 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Liu Ying <victor.liu@....com>
Cc: devicetree@...r.kernel.org, imx@...ts.linux.dev, 
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org, 
	robh@...nel.org, krzk+dt@...nel.org, conor+dt@...nel.org, shawnguo@...nel.org, 
	s.hauer@...gutronix.de, kernel@...gutronix.de, festevam@...il.com, 
	andrzej.hajda@...el.com, neil.armstrong@...aro.org, rfoss@...nel.org, 
	Laurent.pinchart@...asonboard.com, jonas@...boo.se, jernej.skrabec@...il.com, 
	maarten.lankhorst@...ux.intel.com, mripard@...nel.org, tzimmermann@...e.de, airlied@...il.com, 
	simona@...ll.ch, marex@...x.de, stefan@...er.ch
Subject: Re: [PATCH 4/5] drm/bridge: imx8mp-hdmi-tx: Set output_port to 1

On Fri, Oct 18, 2024 at 02:48:12PM +0800, Liu Ying wrote:
> Set DW HDMI platform data's output_port to 1 in imx8mp_dw_hdmi_probe()
> so that dw_hdmi_probe() called by imx8mp_dw_hdmi_probe() can tell the
> DW HDMI bridge core driver about the output port we are using, hence
> the next bridge can be found in dw_hdmi_parse_dt() according to the port
> index, and furthermore the next bridge can be attached to bridge chain in
> dw_hdmi_bridge_attach() when the DRM_BRIDGE_ATTACH_NO_CONNECTOR flag is
> set.  The output_port value aligns to the value used by devicetree.
> This is a preparation for making the i.MX8MP LCDIF driver use
> drm_bridge_connector which requires the DRM_BRIDGE_ATTACH_NO_CONNECTOR
> flag.
> 
> Signed-off-by: Liu Ying <victor.liu@....com>
> ---
>  drivers/gpu/drm/bridge/imx/imx8mp-hdmi-tx.c | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/gpu/drm/bridge/imx/imx8mp-hdmi-tx.c b/drivers/gpu/drm/bridge/imx/imx8mp-hdmi-tx.c
> index 8fcc6d18f4ab..54a53f96929a 100644
> --- a/drivers/gpu/drm/bridge/imx/imx8mp-hdmi-tx.c
> +++ b/drivers/gpu/drm/bridge/imx/imx8mp-hdmi-tx.c
> @@ -96,6 +96,7 @@ static int imx8mp_dw_hdmi_probe(struct platform_device *pdev)
>  		return dev_err_probe(dev, PTR_ERR(hdmi->pixclk),
>  				     "Unable to get pixel clock\n");
>  
> +	plat_data->output_port = 1;

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.

Last, but not least, this changes behaviour of the connector.
dw_hdmi_connector_create() implements CEC support, handles
ycbcr_420_allowed, HDR metadata, etc.

We are slowly moving towards the supporting all of this in bridge
connector via the HDMI Connector framework, but this is not
implemented for now.

>  	plat_data->mode_valid = imx8mp_hdmi_mode_valid;
>  	plat_data->phy_ops = &imx8mp_hdmi_phy_ops;
>  	plat_data->phy_name = "SAMSUNG HDMI TX PHY";
> -- 
> 2.34.1
> 

-- 
With best wishes
Dmitry