Re: [PATCH][next] drm/rockchip: Remove redundant assignment of pointer connector

[Alex Bee]

Hi Heiko,

Am 22.09.21 um 18:45 schrieb Heiko Stübner:
> Hi Alex,
>
> Am Mittwoch, 22. September 2021, 18:35:38 CEST schrieb Alex Bee:
> > Hi Colin,
> > Am 22.09.21 um 13:24 schrieb Colin King:
> > > From: Colin Ian King <colin.king@xxxxxxxxxxxxx>
> > >
> > > The pointer connector is being assigned a value that is never
> > > read, it is being updated immediately afterwards. The assignment
> > > is redundant and can be removed.
> > The pointer to the connector is used in rockchip_rgb_fini for
> > drm_connector_cleanup.
> > It's pretty much the same for the encoder, btw.
> I think the issue is more the two lines
>
> 	connector = &rgb->connector;
>   	connector = drm_bridge_connector_init(rgb->drm_dev, encoder);
>
> hence the connector = &rgb->connector being overwritten immediately after
>
> Now that I look at it again, the whole approach looks strange.
> drm_bridge_connector_init() creates the connector structure and
> returns a pointer to it.

Totally agreed.

The main reason I was doing it that way, was the way it was done already 
in rockchip_lvds.c, where the connector was already existent in the 
struct rockchip_lvds (and was already used in the panel-case - all 
places where it is used accept pointers also, btw) and is *no* pointer - 
and is done already this very strange way.

I wanted to re-use it for the bridge-case and didn't want to differ in 
coding in rockchip-rgb to much.

The only reason I can think of, why it was done that way is, that we 
might need a pointer to a fully initialized struct drm_connector for 
some reason (drm_connector_cleanup ?), what we wouldn't have if have 
just a pointer and something goes wrong before drm_connector_init 
respectivly drm_bridge_connector_init.

Alex


> So the first line below sets the connector pointer to point to the
> &rgb->connector element and the second line then set a completely
> different address into it.
>
> So the connector element in rockchip_lvds and rockchip_rgb should actually
> become a pointer itself to hold the connector element returned from
> drm_bridge_connector_init() .
>
>
> Heiko
>
> > Regards,
> >
> > Alex
> > > Addresses-Coverity: ("Unused value")
> > > Signed-off-by: Colin Ian King <colin.king@xxxxxxxxxxxxx>
> > > ---
> > >    drivers/gpu/drm/rockchip/rockchip_rgb.c | 1 -
> > >    1 file changed, 1 deletion(-)
> > >
> > > diff --git a/drivers/gpu/drm/rockchip/rockchip_rgb.c b/drivers/gpu/drm/rockchip/rockchip_rgb.c
> > > index 09be9678f2bd..18fb84068a64 100644
> > > --- a/drivers/gpu/drm/rockchip/rockchip_rgb.c
> > > +++ b/drivers/gpu/drm/rockchip/rockchip_rgb.c
> > > @@ -150,7 +150,6 @@ struct rockchip_rgb *rockchip_rgb_init(struct device *dev,
> > >    	if (ret)
> > >    		goto err_free_encoder;
> > >    
> > > -	connector = &rgb->connector;
> > >    	connector = drm_bridge_connector_init(rgb->drm_dev, encoder);
> > >    	if (IS_ERR(connector)) {
> > >    		DRM_DEV_ERROR(drm_dev->dev,