Re: [PATCH] drm/i915: rc6 residency (fix the fix)

[Chris Wilson <chris@chris-wilson.co.uk>]

On Fri, 20 Apr 2012 11:50:01 -0700, Ben Widawsky <ben@bwidawsk.net> wrote:
> Chris' fix for my 32b breakage was incorrect. do_div returns a
> remainder. Go back to a divide macro which is more 32b friendly.
> 
> Tested on x86-64.
> 
> This has only been compile tested on 32b systems.
Doesn't compile on my 32-bit systems.

Still does a 64-bit divide.
 
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=48756
> Cc: Chris Wilson <chris@chris-wilson.co.uk>
> Signed-off-by: Ben Widawsky <benjamin.widawsky@intel.com>
> ---
>  drivers/gpu/drm/i915/i915_sysfs.c |    4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_sysfs.c b/drivers/gpu/drm/i915/i915_sysfs.c
> index f1b5108..bd6350b 100644
> --- a/drivers/gpu/drm/i915/i915_sysfs.c
> +++ b/drivers/gpu/drm/i915/i915_sysfs.c
> @@ -39,8 +39,8 @@ static u32 calc_residency(struct drm_device *dev, const u32 reg)
>  	if (!intel_enable_rc6(dev))
>  		return 0;
>  
> -	raw_time = I915_READ(reg) * 128ULL + 500;
> -	return do_div(raw_time, 100000);
> +	raw_time = I915_READ(reg) * 128ULL;
> +	return DIV_ROUND_UP_ULL(raw_time, 1000) / 100;
return (u32)DIV_ROUND_UP_ULL(raw_time, 1000) / 100;
-Chris

-- 
Chris Wilson, Intel Open Source Technology Centre