[PATCH] drm: nouveau: fix nouveau_backlight compiling error

[Lyude Paul]

This needs a fixes tag:

	Fixes: 6eca310e8924 ("drm/nouveau/kms/nv50-: Add basic DPCD backlight support for nouveau")

with that fixed:

Reviewed-by: Lyude Paul <lyude at redhat.com>

On Tue, 2021-06-15 at 11:16 +0800, Chen Jiahao wrote:
> There is a compiling error in disp.c while not selecting
> CONFIG_DRM_NOUVEAU_BACKLIGHT:
> 
> drivers/gpu/drm/nouveau/dispnv50/disp.c: In function
> ‘nv50_sor_atomic_disable’:
> drivers/gpu/drm/nouveau/dispnv50/disp.c:1665:52: error:
> ‘struct nouveau_connector’ has no member named ‘backlight’
>  1665 |  struct nouveau_backlight *backlight = nv_connector->backlight;
>       |                                                    ^~
> drivers/gpu/drm/nouveau/dispnv50/disp.c:1670:28: error: dereferencing
> pointer
> to incomplete type ‘struct nouveau_backlight’
>  1670 |  if (backlight && backlight->uses_dpcd) {
>       |                            ^~
> 
> The problem is solved by adding the CONFIG_DRM_NOUVEAU_BACKLIGHT dependency
> where struct nouveau_backlight is used.
> 
> Signed-off-by: Chen Jiahao <chenjiahao16 at huawei.com>
> ---
>  drivers/gpu/drm/nouveau/dispnv50/disp.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/gpu/drm/nouveau/dispnv50/disp.c
> b/drivers/gpu/drm/nouveau/dispnv50/disp.c
> index 093e1f7163b3..d266b7721e29 100644
> --- a/drivers/gpu/drm/nouveau/dispnv50/disp.c
> +++ b/drivers/gpu/drm/nouveau/dispnv50/disp.c
> @@ -1662,17 +1662,21 @@ nv50_sor_atomic_disable(struct drm_encoder *encoder,
> struct drm_atomic_state *st
>         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);
> +#ifdef CONFIG_DRM_NOUVEAU_BACKLIGHT
>         struct nouveau_backlight *backlight = nv_connector->backlight;
> +#endif
>         struct drm_dp_aux *aux = &nv_connector->aux;
>         int ret;
>         u8 pwr;
>  
> +#ifdef CONFIG_DRM_NOUVEAU_BACKLIGHT
>         if (backlight && backlight->uses_dpcd) {
>                 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);

-- 
Cheers,
 Lyude Paul (she/her)
 Software Engineer at Red Hat