Re: [PATCH] drm/panel: novatek-nt35950: Improve error handling

[AngeloGioacchino Del Regno]

Il 17/04/23 15:38, Konrad Dybcio ha scritto:
> On 17.04.2023 11:44, AngeloGioacchino Del Regno wrote:
> > Il 17/04/23 11:44, AngeloGioacchino Del Regno ha scritto:
> > > Il 17/04/23 09:25, Neil Armstrong ha scritto:
> > > > On 15/04/2023 13:00, Konrad Dybcio wrote:
> > > > > In a very peculiar case when probing and registering with the secondary
> > > > > DSI host succeeds, but the OF backlight or DSI attachment fails, the
> > > > > primary DSI device is automatically cleaned up, but the secondary one
> > > > > is not, leading to -EEXIST when the driver core tries to handle
> > > > > -EPROBE_DEFER.
> > > > >
> > > > > Unregister the DSI1 device manually on failure to prevent that.
> > > > >
> > > > > Fixes: 623a3531e9cf ("drm/panel: Add driver for Novatek NT35950 DSI DriverIC panels")
> > > > > Signed-off-by: Konrad Dybcio <konrad.dybcio@xxxxxxxxxx>
> > > > > ---
> > > > >    drivers/gpu/drm/panel/panel-novatek-nt35950.c | 8 +++++++-
> > > > >    1 file changed, 7 insertions(+), 1 deletion(-)
> > > > >
> > > > > diff --git a/drivers/gpu/drm/panel/panel-novatek-nt35950.c b/drivers/gpu/drm/panel/panel-novatek-nt35950.c
> > > > > index abf752b36a52..7498fc6258bb 100644
> > > > > --- a/drivers/gpu/drm/panel/panel-novatek-nt35950.c
> > > > > +++ b/drivers/gpu/drm/panel/panel-novatek-nt35950.c
> > > > > @@ -585,8 +585,11 @@ static int nt35950_probe(struct mipi_dsi_device *dsi)
> > > > >                   DRM_MODE_CONNECTOR_DSI);
> > > > >        ret = drm_panel_of_backlight(&nt->panel);
> > > > > -    if (ret)
> > > > > +    if (ret) {
> > >
> > > If this is not a dual-DSI case, nt->dsi[1] will be NULL: I agree it's still
> > > fine as in the kernel won't crash in that case, but for logical correctness
> > > I would still account for that:
> > >
> > >           if (num_dsis == 2)
> > >               mipi_dsi_device_unregister(nt->dsi[1]);
> > >
> > > > > +        mipi_dsi_device_unregister(nt->dsi[1]);
> > > > > +
> > > > >            return dev_err_probe(dev, ret, "Failed to get backlight\n");
> > > > > +    }
> > > > >        drm_panel_add(&nt->panel);
> > > > > @@ -602,6 +605,9 @@ static int nt35950_probe(struct mipi_dsi_device *dsi)
> > > > >            ret = mipi_dsi_attach(nt->dsi[i]);
> > > > >            if (ret < 0) {
> > >
> > > Same here, please add a check for num_dsis.
> Right, I'll send an incremental patch to fix the fix, thanks
> for spotting this!

You're welcome! Please make sure to Cc me so that I can timely give you a review!

Cheers,
Angelo