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

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Message-ID: <5035853.0VBMTVartN@steina-w>
Date: Fri, 18 Oct 2024 15:12:49 +0200
From: Alexander Stein <alexander.stein@...tq-group.com>
To: Liu Ying <victor.liu@....com>, dri-devel@...ts.freedesktop.org
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, Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Subject: Re: [PATCH 4/5] drm/bridge: imx8mp-hdmi-tx: Set output_port to 1

Am Freitag, 18. Oktober 2024, 14:31:20 CEST schrieb Dmitry Baryshkov:
> 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.

Mh, I was suspecting the same, but I couldn't see any regression regarding CEC.
Maybe the change is not doing what it is supposed to do...
I'll check again on Monday.

Best regards,
Alexander

> 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";
> 
> 


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