linux-kernel - Re: [PATCH 4/4] drm: rcar-du: mipi-dsi: Support bridge probe ordering

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Message-ID: <163828809390.3059017.11403962735628365262@Monstersaurus>
Date:   Tue, 30 Nov 2021 16:01:33 +0000
From:   Kieran Bingham <kieran.bingham+renesas@...asonboard.com>
To:     Jagan Teki <jagan@...rulasolutions.com>
Cc:     Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        linux-renesas-soc@...r.kernel.org, linux-kernel@...r.kernel.org,
        dri-devel@...ts.freedesktop.org
Subject: Re: [PATCH 4/4] drm: rcar-du: mipi-dsi: Support bridge probe ordering

Hi Jagan,

Quoting Jagan Teki (2021-11-30 07:38:57)
> Hi Kieran,
> 
> On Fri, Nov 26, 2021 at 3:45 PM Kieran Bingham
> <kieran.bingham+renesas@...asonboard.com> wrote:
> >
> > The bridge probe ordering for DSI devices has been clarified and further
> > documented in
> >
> > To support connecting with the SN65DSI86 device after commit c3b75d4734cb
> > ("drm/bridge: sn65dsi86: Register and attach our DSI device at probe"),
> > update to the new probe ordering to remove a perpetual -EPROBE_DEFER
> > loop between the two devices.
> >
> > Signed-off-by: Kieran Bingham <kieran.bingham+renesas@...asonboard.com>
> > ---
> >  drivers/gpu/drm/rcar-du/rcar_mipi_dsi.c | 48 +++++++++++++------------
> >  1 file changed, 26 insertions(+), 22 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/rcar-du/rcar_mipi_dsi.c b/drivers/gpu/drm/rcar-du/rcar_mipi_dsi.c
> > index 833f4480bdf3..f783bacee8da 100644
> > --- a/drivers/gpu/drm/rcar-du/rcar_mipi_dsi.c
> > +++ b/drivers/gpu/drm/rcar-du/rcar_mipi_dsi.c
> > @@ -639,6 +639,8 @@ static int rcar_mipi_dsi_host_attach(struct mipi_dsi_host *host,
> >                                         struct mipi_dsi_device *device)
> >  {
> >         struct rcar_mipi_dsi *dsi = host_to_rcar_mipi_dsi(host);
> > +       struct drm_panel *panel;
> > +       int ret;
> >
> >         if (device->lanes > dsi->num_data_lanes)
> >                 return -EINVAL;
> > @@ -646,12 +648,36 @@ static int rcar_mipi_dsi_host_attach(struct mipi_dsi_host *host,
> >         dsi->lanes = device->lanes;
> >         dsi->format = device->format;
> >
> > +       ret = drm_of_find_panel_or_bridge(dsi->dev->of_node, 1, 0, &panel,
> > +                                         &dsi->next_bridge);
> > +       if (ret) {
> > +               dev_err_probe(dsi->dev, ret, "could not find next bridge\n");
> > +               return ret;
> > +       }
> > +
> > +       if (!dsi->next_bridge) {
> > +               dsi->next_bridge = devm_drm_panel_bridge_add(dsi->dev, panel);
> > +               if (IS_ERR(dsi->next_bridge)) {
> > +                       dev_err(dsi->dev, "failed to create panel bridge\n");
> > +                       return PTR_ERR(dsi->next_bridge);
> > +               }
> > +       }
> 
> Can we use the new function devm_drm_of_get_bridge instead of the entire code?

I've just tried this, and it works, so yes we can.
I'll update the branch and re-send it for Laurent to collect and
apply/squash whichever works best.

Thanks.

Kieran



> 
> Jagan.