Re: [PATCH 6/7] drm/i915: Switch intel_usecs_to_scanlines() to 64bit maths

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

On Tue, 28 May 2024, Ville Syrjala <ville.syrjala@linux.intel.com> wrote:
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
>
> Dotclocks can reach ~1GHz these days, so intel_usecs_to_scanlines(),
> with its 32bit maths, is currently limited to a few milliseconds.
> I want bigger numbers in DSB selftests, so switch over to 64bit
> maths.
>
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>

Reviewed-by: Jani Nikula <jani.nikula@intel.com>

> ---
>  drivers/gpu/drm/i915/display/intel_crtc.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_crtc.c b/drivers/gpu/drm/i915/display/intel_crtc.c
> index ca6dc1dc56c8..17edd6099287 100644
> --- a/drivers/gpu/drm/i915/display/intel_crtc.c
> +++ b/drivers/gpu/drm/i915/display/intel_crtc.c
> @@ -454,8 +454,8 @@ int intel_usecs_to_scanlines(const struct drm_display_mode *adjusted_mode,
>  	if (!adjusted_mode->crtc_htotal)
>  		return 1;
>  
> -	return DIV_ROUND_UP(usecs * adjusted_mode->crtc_clock,
> -			    1000 * adjusted_mode->crtc_htotal);
> +	return DIV_ROUND_UP_ULL(mul_u32_u32(usecs, adjusted_mode->crtc_clock),
> +				1000 * adjusted_mode->crtc_htotal);
>  }
>  
>  /**

-- 
Jani Nikula, Intel