Re: [PATCH 18/22] video: Rockchip: fix zero division in rk3588_calc_cru_cfg

[Sascha Hauer <s.hauer@pengutronix.de>]

On Thu, Mar 13, 2025 at 08:34:41AM +0100, Ahmad Fatoum wrote:
> This was detected by clang-analyzer and I don't understand how that
> function could have ever worked, because it's running into the zero
> division in the "successful" code path.

The driver is only tested on rk3568, so this code path likely never
executed.

sascha

> 
> Peeking at rk3568_set_intf_mux, the CRTC clock is passed by the caller
> in barebox, so let's do the same for rk3588_calc_cru_cfg.
> 
> Fixes: c8c0833beb77 ("video: Rockchip: Add VOP2 driver")
> Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
> ---
>  drivers/video/rockchip/rockchip_drm_vop2.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/video/rockchip/rockchip_drm_vop2.c b/drivers/video/rockchip/rockchip_drm_vop2.c
> index 3a1c951ec7e4..f15ef1b57bf5 100644
> --- a/drivers/video/rockchip/rockchip_drm_vop2.c
> +++ b/drivers/video/rockchip/rockchip_drm_vop2.c
> @@ -743,10 +743,10 @@ static unsigned long rk3588_calc_dclk(unsigned long child_clk, unsigned long max
>   */
>  static unsigned long rk3588_calc_cru_cfg(struct vop2_video_port *vp, int id,
>  					 int *dclk_core_div, int *dclk_out_div,
> -					 int *if_pixclk_div, int *if_dclk_div)
> +					 int *if_pixclk_div, int *if_dclk_div,
> +					 u32 crtc_clock)
>  {
>  	struct vop2 *vop2 = vp->vop2;
> -	u32 crtc_clock = 0;
>  	unsigned long v_pixclk = crtc_clock * 1000LL; /* video timing pixclk */
>  	unsigned long dclk_core_rate = v_pixclk >> 2;
>  	unsigned long dclk_rate = v_pixclk;
> @@ -856,7 +856,7 @@ static unsigned long rk3588_set_intf_mux(struct vop2_video_port *vp, int id, u32
>  	u32 die, dip, div, vp_clk_div, val;
>  
>  	clock = rk3588_calc_cru_cfg(vp, id, &dclk_core_div, &dclk_out_div,
> -				    &if_pixclk_div, &if_dclk_div);
> +				    &if_pixclk_div, &if_dclk_div, clock);
>  	if (!clock)
>  		return 0;
>  
> -- 
> 2.39.5
> 
> 
> 

-- 
Pengutronix e.K.                           |                             |
Steuerwalder Str. 21                       | http://www.pengutronix.de/  |
31137 Hildesheim, Germany                  | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |