Re: [Intel-gfx] [PATCH] drm/i915/display: mode clock check related to max dotclk frequency

[Jani Nikula <jani.nikula@linux.intel.com>]

On Wed, 09 Nov 2022, Nischal Varide <nischal.varide@intel.com> wrote:
> A check on mode->clock to see if is greater than i915->max_dotclk_freq
> or greater than 2 * (i915_max_dotclk_freq) in case of big-joiner and
> return an -EINVAL in both the cases

The commit message should explain *why* the change is being done.

>
> Signed-off-by: Nischal Varide <nischal.varide@intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_dp.c | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
> index 7400d6b4c587..813f4c369dda 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -995,6 +995,10 @@ intel_dp_mode_valid(struct drm_connector *_connector,
>  		bigjoiner = true;
>  		max_dotclk *= 2;
>  	}
> +
> +	if (mode->clock > max_dotclk)
> +		return -EINVAL;
> +

The return type of this function is enum drm_mode_status, which
indicates the reason for rejecting the mode. It's not a negative error
code.

Near the top of the function we have "target_clock = mode->clock;"
making the above identical to the check we already have below. Apart
from the incorrect return code.

What are you trying to do?

BR,
Jani.


>  	if (target_clock > max_dotclk)
>  		return MODE_CLOCK_HIGH;




-- 
Jani Nikula, Intel Open Source Graphics Center