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From:   Karol Herbst <kherbst@redhat.com>
Date:   Fri, 23 Jul 2021 17:15:43 +0200
Message-ID: <CACO55tvQoCnjQWRJhrJ+8TzY5MuDDSUSnwd5AU8G1qsQYCSCBg@mail.gmail.com>
Subject: Re: [PATCH] drm/nouveau/kms/nv50-: fix build failure with CONFIG_BACKLIGHT=n
To:     Randy Dunlap <rdunlap@infradead.org>
Cc:     Arnd Bergmann <arnd@kernel.org>, Ben Skeggs <bskeggs@redhat.com>,
        David Airlie <airlied@linux.ie>,
        Daniel Vetter <daniel@ffwll.ch>, Lyude Paul <lyude@redhat.com>,
        Arnd Bergmann <arnd@arndb.de>,
        nouveau <nouveau@lists.freedesktop.org>,
        LKML <linux-kernel@vger.kernel.org>,
        dri-devel <dri-devel@lists.freedesktop.org>,
        Nikola Cornij <nikola.cornij@amd.com>
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On Fri, Jul 23, 2021 at 5:10 PM Randy Dunlap <rdunlap@infradead.org> wrote:
>
> On 7/23/21 2:15 AM, Arnd Bergmann 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>
> > ---
> >  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);
> >
>
> Hm, only Lyude Paul replied to this patch:
>
> https://lore.kernel.org/lkml/20210714171523.413-1-rdunlap@infradead.org/
>

what's actually the use case of compiling with
CONFIG_DRM_NOUVEAU_BACKLIGHT=n anyway?

>
>
> --
> ~Randy
>