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Subject: Re: [PATCH] drm/nouveau/kms/nv50-: fix build failure with
 CONFIG_BACKLIGHT=n
To:     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>
Cc:     Arnd Bergmann <arnd@arndb.de>,
        =?UTF-8?B?VmlsbGUgU3lyasOkbMOk?= <ville.syrjala@linux.intel.com>,
        Nikola Cornij <nikola.cornij@amd.com>,
        dri-devel@lists.freedesktop.org, nouveau@lists.freedesktop.org,
        linux-kernel@vger.kernel.org
References: <20210723091534.1730564-1-arnd@kernel.org>
From:   Randy Dunlap <rdunlap@infradead.org>
Message-ID: <a618e29a-e4b7-bda4-a3e0-7dfd67d64e92@infradead.org>
Date:   Fri, 23 Jul 2021 08:10:43 -0700
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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/


-- 
~Randy