Re: [PATCH 1/1] drm/xe: Fix conversion from clock ticks to milliseconds

["Dixit, Ashutosh" <ashutosh.dixit@intel.com>]

On Mon, 17 Nov 2025 11:48:43 -0800, Harish Chegondi wrote:
>
> When tick counts are large and multiplication by MSEC_PER_SEC is larger
> than 64 bits, the conversion from clock ticks to milliseconds can go bad.
>
> Use mul_u64_u32_div() instead.
>
> Cc: Ashutosh Dixit <ashutosh.dixit@intel.com>
> Signed-off-by: Harish Chegondi <harish.chegondi@intel.com>
> Suggested-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>

With:

Fixes: 49cc215aad7f ("drm/xe: Add xe_gt_clock_interval_to_ms helper"

Reviewed-by: Ashutosh Dixit <ashutosh.dixit@intel.com>

> ---
>  drivers/gpu/drm/xe/xe_gt_clock.c | 7 +------
>  1 file changed, 1 insertion(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/xe/xe_gt_clock.c b/drivers/gpu/drm/xe/xe_gt_clock.c
> index 00f5972c14dc..bfc25c46f798 100644
> --- a/drivers/gpu/drm/xe/xe_gt_clock.c
> +++ b/drivers/gpu/drm/xe/xe_gt_clock.c
> @@ -74,11 +74,6 @@ int xe_gt_clock_init(struct xe_gt *gt)
>	return 0;
>  }
>
> -static u64 div_u64_roundup(u64 n, u32 d)
> -{
> -	return div_u64(n + d - 1, d);
> -}
> -
>  /**
>   * xe_gt_clock_interval_to_ms - Convert sampled GT clock ticks to msec
>   *
> @@ -89,5 +84,5 @@ static u64 div_u64_roundup(u64 n, u32 d)
>   */
>  u64 xe_gt_clock_interval_to_ms(struct xe_gt *gt, u64 count)
>  {
> -	return div_u64_roundup(count * MSEC_PER_SEC, gt->info.reference_clock);
> +	return mul_u64_u32_div(count, MSEC_PER_SEC, gt->info.reference_clock);
>  }
> --
> 2.43.0
>