On Fri, May 17, 2019 at 05:37:21PM +0100, Robin Murphy wrote:
> Rather than allowing any old mode through, then subsequently refusing
> unmatchable clock rates in atomic_check when it's too late to back out
> and pick a different mode, let's do that validation up-front where it
> will cause unsupported modes to be correctly pruned in the first place.
> 
> This also eliminates an issue whereby a perceived clock rate of 0 would
> cause atomic disable to fail and prevent the module from being unloaded.
> 
> Signed-off-by: Robin Murphy <robin.mur...@arm.com>

Acked-by: Liviu Dudau <liviu.du...@arm.com>

Thanks for the patch!

Best regards,
Liviu

> ---
> 
> This supersedes my previous patch here:
> https://patchwork.freedesktop.org/patch/288553/
> ---
>  drivers/gpu/drm/arm/hdlcd_crtc.c | 11 +++++------
>  1 file changed, 5 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/gpu/drm/arm/hdlcd_crtc.c 
> b/drivers/gpu/drm/arm/hdlcd_crtc.c
> index 0b2b62f8fa3c..ecac6fe0b213 100644
> --- a/drivers/gpu/drm/arm/hdlcd_crtc.c
> +++ b/drivers/gpu/drm/arm/hdlcd_crtc.c
> @@ -186,20 +186,19 @@ static void hdlcd_crtc_atomic_disable(struct drm_crtc 
> *crtc,
>       clk_disable_unprepare(hdlcd->clk);
>  }
>  
> -static int hdlcd_crtc_atomic_check(struct drm_crtc *crtc,
> -                                struct drm_crtc_state *state)
> +static enum drm_mode_status hdlcd_crtc_mode_valid(struct drm_crtc *crtc,
> +             const struct drm_display_mode *mode)
>  {
>       struct hdlcd_drm_private *hdlcd = crtc_to_hdlcd_priv(crtc);
> -     struct drm_display_mode *mode = &state->adjusted_mode;
>       long rate, clk_rate = mode->clock * 1000;
>  
>       rate = clk_round_rate(hdlcd->clk, clk_rate);
>       if (rate != clk_rate) {
>               /* clock required by mode not supported by hardware */
> -             return -EINVAL;
> +             return MODE_NOCLOCK;
>       }
>  
> -     return 0;
> +     return MODE_OK;
>  }
>  
>  static void hdlcd_crtc_atomic_begin(struct drm_crtc *crtc,
> @@ -220,7 +219,7 @@ static void hdlcd_crtc_atomic_begin(struct drm_crtc *crtc,
>  }
>  
>  static const struct drm_crtc_helper_funcs hdlcd_crtc_helper_funcs = {
> -     .atomic_check   = hdlcd_crtc_atomic_check,
> +     .mode_valid     = hdlcd_crtc_mode_valid,
>       .atomic_begin   = hdlcd_crtc_atomic_begin,
>       .atomic_enable  = hdlcd_crtc_atomic_enable,
>       .atomic_disable = hdlcd_crtc_atomic_disable,
> -- 
> 2.21.0.dirty
> 

-- 
====================
| I would like to |
| fix the world,  |
| but they're not |
| giving me the   |
 \ source code!  /
  ---------------
    ¯\_(ツ)_/¯

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