[PATCH v2 1/2] drm: rcar-du: mipi-dsi: Support bridge probe ordering

[Kieran Bingham]

Quoting Laurent Pinchart (2021-12-01 04:38:46)
> Hi Kieran,
> 
> Thank you for the patch.
> 
> On Tue, Nov 30, 2021 at 04:25:12PM +0000, Kieran Bingham wrote:
> > The bridge probe ordering for DSI devices has been clarified and further
> > documented in
> 
> I've read the document and
> 

Good, I'm glad you've fully got the

> 
> :-)

Sorry, not sure how I missed that, I must have failed to paste in the
link to the DSI probe documentation. But as you've read that, and now
this is squashed, I think this is done anyway.

Thanks for handling the integrations.

--
Kieran


> 
> > 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 at ideasonboard.com>
> > 
> > ---
> > v2
> > - Remove now unused panel variable from rcar_mipi_dsi_probe()
> > 
> >  drivers/gpu/drm/rcar-du/rcar_mipi_dsi.c | 49 +++++++++++++------------
> >  1 file changed, 26 insertions(+), 23 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/rcar-du/rcar_mipi_dsi.c b/drivers/gpu/drm/rcar-du/rcar_mipi_dsi.c
> > index 50e922328fed..0a9f197ef62c 100644
> > --- a/drivers/gpu/drm/rcar-du/rcar_mipi_dsi.c
> > +++ b/drivers/gpu/drm/rcar-du/rcar_mipi_dsi.c
> > @@ -637,6 +637,8 @@ 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;
> > @@ -644,12 +646,36 @@ 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");
> 
> dev_err_probe() should only be used in probe(), and this function isn't
> guaranteed to be called at probe time only.
> 
> This isn't a big deal as the next patch fixes this, and both will be
> squashed. Furthermore, rcar_mipi_dsi_host_attach() should only be called
> when the DSI device gets registered, which should happen after it
> registers its bridge, so I don't think we can see a probe deferral here.
> 
> Other than that the patch looks fine, I'll squash it with the DSI
> driver.
> 
> > +             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);
> > +             }
> > +     }
> > +
> > +     /* Initialize the DRM bridge. */
> > +     dsi->bridge.funcs = &rcar_mipi_dsi_bridge_ops;
> > +     dsi->bridge.of_node = dsi->dev->of_node;
> > +     drm_bridge_add(&dsi->bridge);
> > +
> >       return 0;
> >  }
> >  
> >  static int rcar_mipi_dsi_host_detach(struct mipi_dsi_host *host,
> >                                       struct mipi_dsi_device *device)
> >  {
> > +     struct rcar_mipi_dsi *dsi = host_to_rcar_mipi_dsi(host);
> > +
> > +     drm_bridge_remove(&dsi->bridge);
> > +
> >       return 0;
> >  }
> >  
> > @@ -731,7 +757,6 @@ static int rcar_mipi_dsi_get_clocks(struct rcar_mipi_dsi *dsi)
> >  static int rcar_mipi_dsi_probe(struct platform_device *pdev)
> >  {
> >       struct rcar_mipi_dsi *dsi;
> > -     struct drm_panel *panel;
> >       struct resource *mem;
> >       int ret;
> >  
> > @@ -764,21 +789,6 @@ static int rcar_mipi_dsi_probe(struct platform_device *pdev)
> >               return PTR_ERR(dsi->rstc);
> >       }
> >  
> > -     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);
> > -             }
> > -     }
> > -
> >       /* Initialize the DSI host. */
> >       dsi->host.dev = dsi->dev;
> >       dsi->host.ops = &rcar_mipi_dsi_host_ops;
> > @@ -786,11 +796,6 @@ static int rcar_mipi_dsi_probe(struct platform_device *pdev)
> >       if (ret < 0)
> >               return ret;
> >  
> > -     /* Initialize the DRM bridge. */
> > -     dsi->bridge.funcs = &rcar_mipi_dsi_bridge_ops;
> > -     dsi->bridge.of_node = dsi->dev->of_node;
> > -     drm_bridge_add(&dsi->bridge);
> > -
> >       return 0;
> >  }
> >  
> > @@ -798,8 +803,6 @@ static int rcar_mipi_dsi_remove(struct platform_device *pdev)
> >  {
> >       struct rcar_mipi_dsi *dsi = platform_get_drvdata(pdev);
> >  
> > -     drm_bridge_remove(&dsi->bridge);
> > -
> >       mipi_dsi_host_unregister(&dsi->host);
> >  
> >       return 0;
> 
> -- 
> Regards,
> 
> Laurent Pinchart