Re: [PATCH v5 2/6] drm: lcdif: Drop unnecessary NULL pointer check on lcdif->bridge

[Marek Vasut]

On 5/10/23 10:30, Ying Liu wrote:
> On Tue, May 9, 2023 at 10:14 AM Marek Vasut <marex@xxxxxxx> wrote:
> > On 5/8/23 07:57, Liu Ying wrote:
> >
> > Hi,
>
> Hi,

Hi,

> > > diff --git a/drivers/gpu/drm/mxsfb/lcdif_kms.c b/drivers/gpu/drm/mxsfb/lcdif_kms.c
> > > index 262bc43b1079..e54200a9fcb9 100644
> > > --- a/drivers/gpu/drm/mxsfb/lcdif_kms.c
> > > +++ b/drivers/gpu/drm/mxsfb/lcdif_kms.c
> > > @@ -394,7 +394,7 @@ static void lcdif_crtc_mode_set_nofb(struct lcdif_drm_private *lcdif,
> > >        struct drm_display_mode *m = &lcdif->crtc.state->adjusted_mode;
> > >        u32 bus_flags = 0;
> > >
> > > -     if (lcdif->bridge && lcdif->bridge->timings)
> > > +     if (lcdif->bridge->timings)
> > >                bus_flags = lcdif->bridge->timings->input_bus_flags;
> > >        else if (bridge_state)
> > >                bus_flags = bridge_state->input_bus_cfg.flags;
> > > @@ -463,30 +463,21 @@ static void lcdif_crtc_atomic_enable(struct drm_crtc *crtc,
> > >        struct drm_display_mode *m = &lcdif->crtc.state->adjusted_mode;
> > >        struct drm_bridge_state *bridge_state = NULL;
> > >        struct drm_device *drm = lcdif->drm;
> > > -     u32 bus_format = 0;
> > > +     u32 bus_format;
> > >        dma_addr_t paddr;
> > >
> > > -     /* If there is a bridge attached to the LCDIF, use its bus format */
> > > -     if (lcdif->bridge) {
> > > -             bridge_state =
> > > -                     drm_atomic_get_new_bridge_state(state,
> > > -                                                     lcdif->bridge);
> > > -             if (!bridge_state)
> > > -                     bus_format = MEDIA_BUS_FMT_FIXED;
> > > -             else
> > > -                     bus_format = bridge_state->input_bus_cfg.format;
> > > -
> > > -             if (bus_format == MEDIA_BUS_FMT_FIXED) {
> > > -                     dev_warn_once(drm->dev,
> > > -                                   "Bridge does not provide bus format, assuming MEDIA_BUS_FMT_RGB888_1X24.\n"
> > > -                                   "Please fix bridge driver by handling atomic_get_input_bus_fmts.\n");
> > > -                     bus_format = MEDIA_BUS_FMT_RGB888_1X24;
> > > -             }
> > > -     }
> > > +     bridge_state = drm_atomic_get_new_bridge_state(state, lcdif->bridge);
> > > +     if (!bridge_state)
> > > +             bus_format = MEDIA_BUS_FMT_FIXED;
> > > +     else
> > > +             bus_format = bridge_state->input_bus_cfg.format;
> >
> > The code below seems to change the logic slightly.
> >
> > Could it happen that:
> > - bridge_state is valid (i.e. non-NULL)
> > - bridge_state->input_bus_cfg.format is set to 0 (i.e. not set) ?
> >     (note that MEDIA_BUS_FMT_FIXED is defined as 0x0001)
>
> Yes, bridge_state->input_bus_cfg.format could be zero.
> Will keep the below default MEDIA_BUS_FMT_RGB888_1X24
> bus format setting in next version.

Thanks for confirming.

The rest of the series looks good, sorry for the delay in reviews.