linux-kernel - Re: [PATCH] drm/lcdif: switch to DRM_BRIDGE_ATTACH_NO

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Date: Mon, 24 Jun 2024 14:49:03 +0300
From: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
To: Alexander Stein <alexander.stein@...tq-group.com>
Cc: Marek Vasut <marex@...x.de>, Stefan Agner <stefan@...er.ch>, 
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>, Maxime Ripard <mripard@...nel.org>, 
	Thomas Zimmermann <tzimmermann@...e.de>, David Airlie <airlied@...il.com>, Daniel Vetter <daniel@...ll.ch>, 
	Shawn Guo <shawnguo@...nel.org>, Sascha Hauer <s.hauer@...gutronix.de>, 
	Pengutronix Kernel Team <kernel@...gutronix.de>, Fabio Estevam <festevam@...il.com>, 
	dri-devel@...ts.freedesktop.org, imx@...ts.linux.dev, 
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] drm/lcdif: switch to DRM_BRIDGE_ATTACH_NO_CONNECTOR

On Mon, 24 Jun 2024 at 14:32, Alexander Stein
<alexander.stein@...tq-group.com> wrote:
>
> Hi,
>
> Am Montag, 24. Juni 2024, 12:31:46 CEST schrieb Dmitry Baryshkov:
> > Existing in-kernel device trees use LCDIF with the dsim + adv7533, dsim
> > + tc358762 or with ldb + panel_bridge. All these combinations support
> > using DRM_BRIDGE_ATTACH_NO_CONNECTOR for bridge attachment.
> >
> > Change lcdif driver to use this flag when attaching the bridge and
> > create drm_bridge_connector afterwards.
> >
> > Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
> > ---
> > Note: compile-tested only.
>
> I gave it a try, but it doesn't work. Despite DSI output it also breaks
> HDMI output, where I at least some error messages:
> [drm:drm_bridge_attach] *ERROR* failed to attach bridge /soc@...us@...00000/hdmi@...d8000 to encoder None-37: -22
> [drm:drm_bridge_attach] *ERROR* failed to attach bridge /soc@...us@...00000/display-bridge@...c4000 to encoder None-37: -22
> imx-lcdif 32fc6000.display-controller: error -EINVAL: Failed to attach bridge for endpoint0
> imx-lcdif 32fc6000.display-controller: error -EINVAL: Cannot connect bridge
> imx-lcdif 32fc6000.display-controller: probe with driver imx-lcdif failed with error -22

Could you please try it with the following change:

diff --git a/drivers/gpu/drm/bridge/imx/imx8mp-hdmi-tx.c
b/drivers/gpu/drm/bridge/imx/imx8mp-hdmi-tx.c
index 13bc570c5473..c87d3e55c00d 100644
--- a/drivers/gpu/drm/bridge/imx/imx8mp-hdmi-tx.c
+++ b/drivers/gpu/drm/bridge/imx/imx8mp-hdmi-tx.c
@@ -94,6 +94,7 @@ 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;

        hdmi->dw_hdmi = dw_hdmi_probe(pdev, plat_data);
        if (IS_ERR(hdmi->dw_hdmi))


>
> Best regards,
> Alexander
>
> > ---
> >  drivers/gpu/drm/mxsfb/lcdif_drv.c | 14 +++++++++++++-
> >  1 file changed, 13 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/gpu/drm/mxsfb/lcdif_drv.c b/drivers/gpu/drm/mxsfb/lcdif_drv.c
> > index 0f895b8a99d6..1d5508449995 100644
> > --- a/drivers/gpu/drm/mxsfb/lcdif_drv.c
> > +++ b/drivers/gpu/drm/mxsfb/lcdif_drv.c
> > @@ -16,6 +16,7 @@
> >
> >  #include <drm/drm_atomic_helper.h>
> >  #include <drm/drm_bridge.h>
> > +#include <drm/drm_bridge_connector.h>
> >  #include <drm/drm_drv.h>
> >  #include <drm/drm_encoder.h>
> >  #include <drm/drm_fbdev_dma.h>
> > @@ -48,6 +49,7 @@ static int lcdif_attach_bridge(struct lcdif_drm_private *lcdif)
> >  {
> >       struct device *dev = lcdif->drm->dev;
> >       struct device_node *ep;
> > +     struct drm_connector *connector;
> >       struct drm_bridge *bridge;
> >       int ret;
> >
> > @@ -96,13 +98,23 @@ static int lcdif_attach_bridge(struct lcdif_drm_private *lcdif)
> >                       return ret;
> >               }
> >
> > -             ret = drm_bridge_attach(encoder, bridge, NULL, 0);
> > +             ret = drm_bridge_attach(encoder, bridge, NULL, DRM_BRIDGE_ATTACH_NO_CONNECTOR);
> >               if (ret) {
> >                       of_node_put(ep);
> >                       return dev_err_probe(dev, ret,
> >                                            "Failed to attach bridge for endpoint%u\n",
> >                                            of_ep.id);
> >               }
> > +
> > +             connector = drm_bridge_connector_init(lcdif->drm, encoder);
> > +             if (IS_ERR(connector)) {
> > +                     ret = PTR_ERR(connector);
> > +                     of_node_put(ep);
> > +
> > +                     return dev_err_probe(dev, ret,
> > +                                          "Failed to create bridge connector for endpoint%u\n",
> > +                                          of_ep.id);
> > +             }
> >       }
> >
> >       return 0;
> >
> > ---
> > base-commit: f76698bd9a8ca01d3581236082d786e9a6b72bb7
> > change-id: 20240624-mxc-lcdif-bridge-attach-60368807b2f9
> >
> > Best regards,
> >
>
>
> --
> TQ-Systems GmbH | Mühlstraße 2, Gut Delling | 82229 Seefeld, Germany
> Amtsgericht München, HRB 105018
> Geschäftsführer: Detlef Schneider, Rüdiger Stahl, Stefan Schneider
> http://www.tq-group.com/
>
>


-- 
With best wishes
Dmitry