[Intel-gfx] [PATCH 7/7] drm/i915/skl: WA for watermark calculation based on Arbitrated Display BW

[Damien Lespiau]

On Thu, Jan 14, 2016 at 11:30:31PM +0800, kbuild test robot wrote:
> Hi Mahesh,
> 
> [auto build test ERROR on drm-intel/for-linux-next]
> [also build test ERROR on next-20160114]
> [cannot apply to v4.4]
> [if your patch is applied to the wrong git tree, please drop us a note to help improving the system]
> 
> url:    https://github.com/0day-ci/linux/commits/Shobhit-Kumar/Misc-WM-fixes-and-Arbitrated-Display-Bandwidth-WA-for-SKL/20160114-200444
> base:   git://anongit.freedesktop.org/drm-intel for-linux-next
> config: i386-defconfig (attached as .config)
> reproduce:
>         # save the attached .config to linux build tree
>         make ARCH=i386 
> 
> All errors (new ones prefixed by >>):
> 
>    drivers/built-in.o: In function `skl_update_wm':
> >> intel_pm.c:(.text+0xdcbfb): undefined reference to `__udivdi3'
>    intel_pm.c:(.text+0xdccb7): undefined reference to `__udivdi3'

In case you wonder, compiling for x86 32 bits, this is most likely
because DIV_ROUND_UP() uses a stray '/' operator and you use it with 64
bit values, which will make gcc use a run-time helper function that
isn't part of the kernel.

You need to use DIV_ROUND_UP_ULL(), making sure the second parameter is
32 bits only.

HTH,

-- 
Damien