[Intel-gfx] [PATCH v2 09/11] drm/i915/dp: Report a rounded-down value as the maximum data rate

[Lisovskiy, Stanislav]

On Thu, Nov 16, 2023 at 03:18:39PM +0200, Imre Deak wrote:
> Callers of intel_dp_max_data_rate() use the return value as an upper
> bound for the BW a given mode requires. As such the rounding shouldn't
> result in a bigger value than the actual upper bound. Use round-down
> instead of -closest accordingly.
> 
> Cc: Jani Nikula <jani.nikula at linux.intel.com>
> Signed-off-by: Imre Deak <imre.deak at intel.com>

LGTM,

Reviewed-by: Stanislav Lisovskiy <stanislav.lisovskiy at intel.com>

> ---
>  drivers/gpu/drm/i915/display/intel_dp.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/display/intel_dp.c b/drivers/gpu/drm/i915/display/intel_dp.c
> index 120d435d27ff1..209c27167e057 100644
> --- a/drivers/gpu/drm/i915/display/intel_dp.c
> +++ b/drivers/gpu/drm/i915/display/intel_dp.c
> @@ -413,7 +413,7 @@ intel_dp_max_data_rate(int max_link_rate, int max_lanes)
>  		 */
>  		int max_link_rate_kbps = max_link_rate * 10;
>  
> -		max_link_rate_kbps = DIV_ROUND_CLOSEST_ULL(mul_u32_u32(max_link_rate_kbps, 9671), 10000);
> +		max_link_rate_kbps = DIV_ROUND_DOWN_ULL(mul_u32_u32(max_link_rate_kbps, 9671), 10000);
>  		max_link_rate = max_link_rate_kbps / 8;
>  	}
>  
> @@ -423,7 +423,7 @@ intel_dp_max_data_rate(int max_link_rate, int max_lanes)
>  	 * out to be a nop by coincidence, and can be skipped:
>  	 *
>  	 *	int max_link_rate_kbps = max_link_rate * 10;
> -	 *	max_link_rate_kbps = DIV_ROUND_CLOSEST_ULL(max_link_rate_kbps * 8, 10);
> +	 *	max_link_rate_kbps = DIV_ROUND_DOWN_ULL(max_link_rate_kbps * 8, 10);
>  	 *	max_link_rate = max_link_rate_kbps / 8;
>  	 */
>  
> -- 
> 2.39.2
>