[PATCH 1/1] i915: fix up a raw 64bit divide

[PATCH 1/1] i915: fix up a raw 64bit divide

[Andy Whitcroft]

We are seeing compilation failures on i386 in some environments due
to an undefined reference as below:

    ERROR: "__udivdi3" [drivers/gpu/drm/i915/i915.ko] undefined!

This is generated due to a raw 64 bit divide in the i915 driver.  Fix up
this raw divide.

Signed-off-by: Andy Whitcroft <apw@canonical.com>
---
 drivers/gpu/drm/i915/intel_display.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index 73e7b9c..9f79de3 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -1574,7 +1574,7 @@ igdng_compute_m_n(int bytes_per_pixel, int nlanes,
 
 	temp = (u64) DATA_N * pixel_clock;
 	temp = div_u64(temp, link_clock);
-	m_n->gmch_m = (temp * bytes_per_pixel) / nlanes;
+	m_n->gmch_m = div_u64(temp * bytes_per_pixel, nlanes);
 	m_n->gmch_n = DATA_N;
 	fdi_reduce_ratio(&m_n->gmch_m, &m_n->gmch_n);
 
-- 
1.6.3.rc3.199.g24398

Re: [PATCH 1/1] i915: fix up a raw 64bit divide

[Jesse Barnes]

On Wed,  1 Jul 2009 15:20:59 +0100
Andy Whitcroft <apw@canonical.com> wrote:

> We are seeing compilation failures on i386 in some environments due
> to an undefined reference as below:
> 
>     ERROR: "__udivdi3" [drivers/gpu/drm/i915/i915.ko] undefined!
> 
> This is generated due to a raw 64 bit divide in the i915 driver.  Fix
> up this raw divide.
> 
> Signed-off-by: Andy Whitcroft <apw@canonical.com>

I think building with newer GCCs will prevent this error, but the fix
looks fine.

Acked-by: Jesse Barnes <jbarnes@virtuousgeek.org>

-- 
Jesse Barnes, Intel Open Source Technology Center

Re: [PATCH 1/1] i915: fix up a raw 64bit divide

[Andy Whitcroft]

On Wed, Jul 01, 2009 at 09:12:55AM -0700, Jesse Barnes wrote:
> On Wed,  1 Jul 2009 15:20:59 +0100
> Andy Whitcroft <apw@canonical.com> wrote:
> 
> > We are seeing compilation failures on i386 in some environments due
> > to an undefined reference as below:
> > 
> >     ERROR: "__udivdi3" [drivers/gpu/drm/i915/i915.ko] undefined!
> > 
> > This is generated due to a raw 64 bit divide in the i915 driver.  Fix
> > up this raw divide.
> > 
> > Signed-off-by: Andy Whitcroft <apw@canonical.com>
> 
> I think building with newer GCCs will prevent this error, but the fix
> looks fine.

Yeah I suspect gcc interactions here, as builds on older userspace were
failing in this way but not so in the very latest karmic userspace.  I
suspect its still correct to avoid these currently.

> Acked-by: Jesse Barnes <jbarnes@virtuousgeek.org>

Thanks.

-apw

Re: [PATCH 1/1] i915: fix up a raw 64bit divide

[Zhenyu Wang]

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On 2009.07.01 09:12:55 -0700, Jesse Barnes wrote:
> On Wed,  1 Jul 2009 15:20:59 +0100
> Andy Whitcroft <apw@canonical.com> wrote:
> 
> > We are seeing compilation failures on i386 in some environments due
> > to an undefined reference as below:
> > 
> >     ERROR: "__udivdi3" [drivers/gpu/drm/i915/i915.ko] undefined!
> > 
> > This is generated due to a raw 64 bit divide in the i915 driver.  Fix
> > up this raw divide.
> > 
> > Signed-off-by: Andy Whitcroft <apw@canonical.com>
> 
> I think building with newer GCCs will prevent this error, but the fix
> looks fine.
> 
> Acked-by: Jesse Barnes <jbarnes@virtuousgeek.org>
> 

yeah, sorry I didn't catch that.

Acked-by: Zhenyu Wang <zhenyuw@linux.intel.com>

-- 
Open Source Technology Center, Intel ltd.

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Re: [PATCH 1/1] i915: fix up a raw 64bit divide

[Sergio Luis]

On Wed, Jul 1, 2009 at 1:12 PM, Jesse Barnes<jbarnes@virtuousgeek.org> wrote:
> On Wed,  1 Jul 2009 15:20:59 +0100
> Andy Whitcroft <apw@canonical.com> wrote:
>
>> We are seeing compilation failures on i386 in some environments due
>> to an undefined reference as below:
>>
>>     ERROR: "__udivdi3" [drivers/gpu/drm/i915/i915.ko] undefined!
>>
>> This is generated due to a raw 64 bit divide in the i915 driver.  Fix
>> up this raw divide.
>>
>> Signed-off-by: Andy Whitcroft <apw@canonical.com>
>
> I think building with newer GCCs will prevent this error, but the fix
> looks fine.

I get it in here (31-rc2), with gcc 4.2.4, but only if I have
CONFIG_DEBUG_SECTION_MISMATCH=y. With this patch it works regardless
of that option.

>
> Acked-by: Jesse Barnes <jbarnes@virtuousgeek.org>
>
> --
> Jesse Barnes, Intel Open Source Technology Center
> --