Re: [PATCH] drm/nouveau/kms/nv50-: fix build failure with CONFIG_BACKLIGHT=n

[Karol Herbst <kherbst@redhat.com>]

On Fri, Jul 23, 2021 at 12:10 PM Karol Herbst <kherbst@redhat.com> wrote:
>
> On Fri, Jul 23, 2021 at 11:24 AM Daniel Vetter <daniel@ffwll.ch> wrote:
> >
> > On Fri, Jul 23, 2021 at 11:15 AM Arnd Bergmann <arnd@kernel.org> wrote:
> > >
> > > From: Arnd Bergmann <arnd@arndb.de>
> > >
> > > When the backlight support is disabled, the driver fails to build:
> > >
> > > drivers/gpu/drm/nouveau/dispnv50/disp.c: In function 'nv50_sor_atomic_disable':
> > > drivers/gpu/drm/nouveau/dispnv50/disp.c:1665:59: error: 'struct nouveau_connector' has no member named 'backlight'
> > >  1665 |         struct nouveau_backlight *backlight = nv_connector->backlight;
> > >       |                                                           ^~
> > > drivers/gpu/drm/nouveau/dispnv50/disp.c:1670:35: error: invalid use of undefined type 'struct nouveau_backlight'
> > >  1670 |         if (backlight && backlight->uses_dpcd) {
> > >       |                                   ^~
> > > drivers/gpu/drm/nouveau/dispnv50/disp.c:1671:64: error: invalid use of undefined type 'struct nouveau_backlight'
> > >  1671 |                 ret = drm_edp_backlight_disable(aux, &backlight->edp_info);
> > >       |                                                                ^~
> > >
> > > The patch that introduced the problem already contains some #ifdef
> > > checks, so just add another one that makes it build again.
> > >
> > > Fixes: 6eca310e8924 ("drm/nouveau/kms/nv50-: Add basic DPCD backlight support for nouveau")
> > > Signed-off-by: Arnd Bergmann <arnd@arndb.de>
> >
> > Can we just toss the idea that BACKTLIGHT=n is a reasonable config for
> > drm drivers using backlights, and add depends BACKLIGHT to all of
> > them?
> >
> > I mean this is a perfect source of continued patch streams to keep us
> > all busy, but beyond that I really don't see the point ... I frankly
> > have better things to do, and especially with the big drivers we have
> > making backlight optional saves comparitively nothing.
> > -Daniel
> >
>
> same, I'd just require BACKLIGHT as well tbh.
>

ehhh, get rid of DRM_NOUVEAU_BACKLIGHT I meant.

> > > ---
> > >  drivers/gpu/drm/nouveau/dispnv50/disp.c | 11 +++++++----
> > >  1 file changed, 7 insertions(+), 4 deletions(-)
> > >
> > > diff --git a/drivers/gpu/drm/nouveau/dispnv50/disp.c b/drivers/gpu/drm/nouveau/dispnv50/disp.c
> > > index 093e1f7163b3..fcf53e24db21 100644
> > > --- a/drivers/gpu/drm/nouveau/dispnv50/disp.c
> > > +++ b/drivers/gpu/drm/nouveau/dispnv50/disp.c
> > > @@ -1659,20 +1659,23 @@ static void
> > >  nv50_sor_atomic_disable(struct drm_encoder *encoder, struct drm_atomic_state *state)
> > >  {
> > >         struct nouveau_encoder *nv_encoder = nouveau_encoder(encoder);
> > > -       struct nouveau_drm *drm = nouveau_drm(nv_encoder->base.base.dev);
> > >         struct nouveau_crtc *nv_crtc = nouveau_crtc(nv_encoder->crtc);
> > >         struct nouveau_connector *nv_connector = nv50_outp_get_old_connector(state, nv_encoder);
> > > -       struct nouveau_backlight *backlight = nv_connector->backlight;
> > >         struct drm_dp_aux *aux = &nv_connector->aux;
> > > -       int ret;
> > >         u8 pwr;
> > >
> > > +#ifdef CONFIG_DRM_NOUVEAU_BACKLIGHT
> > > +       struct nouveau_drm *drm = nouveau_drm(nv_encoder->base.base.dev);
> > > +       struct nouveau_backlight *backlight = nv_connector->backlight;
> > > +
> > >         if (backlight && backlight->uses_dpcd) {
> > > -               ret = drm_edp_backlight_disable(aux, &backlight->edp_info);
> > > +               int ret = drm_edp_backlight_disable(aux, &backlight->edp_info);
> > > +
> > >                 if (ret < 0)
> > >                         NV_ERROR(drm, "Failed to disable backlight on [CONNECTOR:%d:%s]: %d\n",
> > >                                  nv_connector->base.base.id, nv_connector->base.name, ret);
> > >         }
> > > +#endif
> > >
> > >         if (nv_encoder->dcb->type == DCB_OUTPUT_DP) {
> > >                 int ret = drm_dp_dpcd_readb(aux, DP_SET_POWER, &pwr);
> > > --
> > > 2.29.2
> > >
> >
> >
> > --
> > Daniel Vetter
> > Software Engineer, Intel Corporation
> > http://blog.ffwll.ch
> >