Re: [PATCH] drm/rockchip: vop2: Drop unused if_dclk_rate variable

[Andy Yan]

Hi:

On 1/4/24 23:58, Heiko Stübner wrote:
> Hi Christian, Andy,
>
> Am Donnerstag, 4. Januar 2024, 15:39:50 CET schrieb Cristian Ciocaltea:
> > Commit 5a028e8f062f ("drm/rockchip: vop2: Add support for rk3588")
> > introduced a variable which ended up being unused.  Remove it.
> >
> > rockchip_drm_vop2.c:1688:23: warning: variable ‘if_dclk_rate’ set but not used [-Wunused-but-set-variable]
> >
> > Signed-off-by: Cristian Ciocaltea <cristian.ciocaltea@xxxxxxxxxxxxx>
>
> in general, please don't send non-series patches as replies to other patches.
> It confuses tooling like b4 way too often, as this patch is not designated
> as a 2/2 (similar to the first one not being 1/2).
>
> > ---
> >   drivers/gpu/drm/rockchip/rockchip_drm_vop2.c | 2 --
> >   1 file changed, 2 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c b/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
> > index 44508c2dd614..923985d4161b 100644
> > --- a/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
> > +++ b/drivers/gpu/drm/rockchip/rockchip_drm_vop2.c
> > @@ -1685,7 +1685,6 @@ static unsigned long rk3588_calc_cru_cfg(struct vop2_video_port *vp, int id,
> >   	unsigned long dclk_core_rate = v_pixclk >> 2;
> >   	unsigned long dclk_rate = v_pixclk;
> >   	unsigned long dclk_out_rate;
> > -	unsigned long if_dclk_rate;
> >   	unsigned long if_pixclk_rate;
> >   	int K = 1;
> >   
> > @@ -1700,7 +1699,6 @@ static unsigned long rk3588_calc_cru_cfg(struct vop2_video_port *vp, int id,
> >   		}
> >   
> >   		if_pixclk_rate = (dclk_core_rate << 1) / K;
> > -		if_dclk_rate = dclk_core_rate / K;
> >   		/*
> >   		 * *if_pixclk_div = dclk_rate / if_pixclk_rate;
> >   		 * *if_dclk_div = dclk_rate / if_dclk_rate;
> >   		 */
> 		*if_pixclk_div = 2;
> 		*if_dclk_div = 4;
>
> with the code continuing with those static constants but the comment
> showing a forumula, I do hope Andy can provide a bit of insight into
> what is happening here.
>
> I.e. I'd really like to understand if that really is just a remnant or
> something different is needed.

This is not a remnant, in my V1, I calculate all the div by formula, but Sascha prefer
more for a constants value[0], so I keep this formula as comments to indicate how these value come from.

[0]https://patchwork.kernel.org/project/linux-rockchip/patch/20231114112855.1771372-1-andyshrk@xxxxxxx/
> Heiko