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

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Message-ID: <22365175.EbdSka62eY@diego>
Date:   Wed, 22 Sep 2021 18:45:24 +0200
From:   Heiko Stübner <heiko@...ech.de>
To:     Colin King <colin.king@...onical.com>,
        Sandy Huang <hjc@...k-chips.com>,
        David Airlie <airlied@...ux.ie>,
        Daniel Vetter <daniel@...ll.ch>,
        dri-devel@...ts.freedesktop.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-rockchip@...ts.infradead.org, Alex Bee <knaerzche@...il.com>
Cc:     kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH][next] drm/rockchip: Remove redundant assignment of pointer connector

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@...onical.com>
> > 
> > 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.

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@...onical.com>
> > ---
> >   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,
> > 
> 
>