When building post V5.5 on my PowerBook G4 Aluminum, the build failed with the
following error:
drivers/gpu/drm/drm_edid.c: In function ‘cea_mode_alternate_timings’:
drivers/gpu/drm/drm_edid.c:3275:2: error: call to ‘__compiletime_assert_3282’
declared with attribute error: BUILD_BUG_ON failed: cea_mode_for_vic(8)->vtotal
!= 262 || cea_mode_for_vic(9)->vtotal != 262 || cea_mode_for_vic(12)->vtotal !=
262 || cea_mode_for_vic(13)->vtotal != 262 || cea_mode_for_vic(23)->vtotal !=
312 || cea_mode_for_vic(24)->vtotal != 312 || cea_mode_for_vic(27)->vtotal !=
312 || cea_mode_for_vic(28)->vtotal != 312
This error was bisected to commit 7befe621ff81 ("drm/edid: Abstract away
cea_edid_modes[]").
This problem is clearly a problem with the gcc compiler on the box, namely gcc
(Ubuntu/Linaro 4.6.3-1ubuntu5) 4.6.3. I had no success finding why the
attributes were wrong, and finally settled on the following hack:
diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index 99769d6c9f84..062bbe2b254a 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -3272,6 +3272,7 @@ cea_mode_alternate_timings(u8 vic, struct drm_display_mode
*mode)
* get the other variants by simply increasing the
* vertical front porch length.
*/
+#ifndef CONFIG_PPC32
BUILD_BUG_ON(cea_mode_for_vic(8)->vtotal != 262 ||
cea_mode_for_vic(9)->vtotal != 262 ||
cea_mode_for_vic(12)->vtotal != 262 ||
@@ -3280,6 +3281,7 @@ cea_mode_alternate_timings(u8 vic, struct drm_display_mode
*mode)
cea_mode_for_vic(24)->vtotal != 312 ||
cea_mode_for_vic(27)->vtotal != 312 ||
cea_mode_for_vic(28)->vtotal != 312);
+#endif
if (((vic == 8 || vic == 9 ||
vic == 12 || vic == 13) && mode->vtotal < 263) ||
Disabling the build check allows me to build and test the post v5.5 versions.
Larry
On Thu, Feb 06, 2020 at 04:46:52PM -0600, Larry Finger wrote:
> When building post V5.5 on my PowerBook G4 Aluminum, the build failed with the
> following error:
>
> drivers/gpu/drm/drm_edid.c: In function ‘cea_mode_alternate_timings’:
> drivers/gpu/drm/drm_edid.c:3275:2: error: call to ‘__compiletime_assert_3282’
> declared with attribute error: BUILD_BUG_ON failed: cea_mode_for_vic(8)->vtotal
> != 262 || cea_mode_for_vic(9)->vtotal != 262 || cea_mode_for_vic(12)->vtotal !=
> 262 || cea_mode_for_vic(13)->vtotal != 262 || cea_mode_for_vic(23)->vtotal !=
> 312 || cea_mode_for_vic(24)->vtotal != 312 || cea_mode_for_vic(27)->vtotal !=
> 312 || cea_mode_for_vic(28)->vtotal != 312
>
> This error was bisected to commit 7befe621ff81 ("drm/edid: Abstract away
> cea_edid_modes[]").
>
> This problem is clearly a problem with the gcc compiler on the box, namely gcc
> (Ubuntu/Linaro 4.6.3-1ubuntu5) 4.6.3. I had no success finding why the
> attributes were wrong, and finally settled on the following hack:
>
> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> index 99769d6c9f84..062bbe2b254a 100644
> --- a/drivers/gpu/drm/drm_edid.c
> +++ b/drivers/gpu/drm/drm_edid.c
> @@ -3272,6 +3272,7 @@ cea_mode_alternate_timings(u8 vic, struct drm_display_mode
> *mode)
> * get the other variants by simply increasing the
> * vertical front porch length.
> */
> +#ifndef CONFIG_PPC32
> BUILD_BUG_ON(cea_mode_for_vic(8)->vtotal != 262 ||
> cea_mode_for_vic(9)->vtotal != 262 ||
> cea_mode_for_vic(12)->vtotal != 262 ||
> @@ -3280,6 +3281,7 @@ cea_mode_alternate_timings(u8 vic, struct drm_display_mode
> *mode)
> cea_mode_for_vic(24)->vtotal != 312 ||
> cea_mode_for_vic(27)->vtotal != 312 ||
> cea_mode_for_vic(28)->vtotal != 312);
> +#endif
>
> if (((vic == 8 || vic == 9 ||
> vic == 12 || vic == 13) && mode->vtotal < 263) ||
>
> Disabling the build check allows me to build and test the post v5.5 versions.
>
> Larry
It's not that the attributes are wrong. The problem is that BUILD_BUG_ON
requires a compile-time evaluatable condition. gcc-4.6 is apparently not
good enough at optimizing to reduce that expression to a constant,
though it was able to do it with the array accesses.
On Thu, Feb 06, 2020 at 06:12:13PM -0500, Arvind Sankar wrote:
> On Thu, Feb 06, 2020 at 04:46:52PM -0600, Larry Finger wrote:
> > When building post V5.5 on my PowerBook G4 Aluminum, the build failed with the
> > following error:
>
> It's not that the attributes are wrong. The problem is that BUILD_BUG_ON
> requires a compile-time evaluatable condition. gcc-4.6 is apparently not
> good enough at optimizing to reduce that expression to a constant,
> though it was able to do it with the array accesses.
Should have noted, it fails on x86 too with gcc-4.6.4, not specific to PPC.
On 2/6/20 5:33 PM, Arvind Sankar wrote:
> On Thu, Feb 06, 2020 at 06:12:13PM -0500, Arvind Sankar wrote:
>> On Thu, Feb 06, 2020 at 04:46:52PM -0600, Larry Finger wrote:
>>> When building post V5.5 on my PowerBook G4 Aluminum, the build failed with the
>>> following error:
>>
>> It's not that the attributes are wrong. The problem is that BUILD_BUG_ON
>> requires a compile-time evaluatable condition. gcc-4.6 is apparently not
>> good enough at optimizing to reduce that expression to a constant,
>> though it was able to do it with the array accesses.
>
> Should have noted, it fails on x86 too with gcc-4.6.4, not specific to PPC.
What pre-processor test would be correct to skip the test for gcc4?
Larry
On Thu, Feb 06, 2020 at 06:29:42PM -0600, Larry Finger wrote:
> On 2/6/20 5:33 PM, Arvind Sankar wrote:
> > On Thu, Feb 06, 2020 at 06:12:13PM -0500, Arvind Sankar wrote:
> >> On Thu, Feb 06, 2020 at 04:46:52PM -0600, Larry Finger wrote:
> >>> When building post V5.5 on my PowerBook G4 Aluminum, the build failed with the
> >>> following error:
> >>
> >> It's not that the attributes are wrong. The problem is that BUILD_BUG_ON
> >> requires a compile-time evaluatable condition. gcc-4.6 is apparently not
> >> good enough at optimizing to reduce that expression to a constant,
> >> though it was able to do it with the array accesses.
> >
> > Should have noted, it fails on x86 too with gcc-4.6.4, not specific to PPC.
>
> What pre-processor test would be correct to skip the test for gcc4?
>
> Larry
>
I think the patch you bisected to is broken. It should not use
BUILD_BUG_ON with a condition that is not obviously compile-time
evaluatable.
On Thu, Feb 06, 2020 at 04:46:52PM -0600, Larry Finger wrote:
> When building post V5.5 on my PowerBook G4 Aluminum, the build failed with the
> following error:
It shouldn't be in 5.5
There's a fix queued
https://cgit.freedesktop.org/drm-misc/commit/?h=drm-misc-next-fixes&id=e1cf35b94c5fd122a8780587559fc6da9fc2dd12
Does that work for you?
>
> drivers/gpu/drm/drm_edid.c: In function ‘cea_mode_alternate_timings’:
> drivers/gpu/drm/drm_edid.c:3275:2: error: call to ‘__compiletime_assert_3282’
> declared with attribute error: BUILD_BUG_ON failed: cea_mode_for_vic(8)->vtotal
> != 262 || cea_mode_for_vic(9)->vtotal != 262 || cea_mode_for_vic(12)->vtotal !=
> 262 || cea_mode_for_vic(13)->vtotal != 262 || cea_mode_for_vic(23)->vtotal !=
> 312 || cea_mode_for_vic(24)->vtotal != 312 || cea_mode_for_vic(27)->vtotal !=
> 312 || cea_mode_for_vic(28)->vtotal != 312
>
> This error was bisected to commit 7befe621ff81 ("drm/edid: Abstract away
> cea_edid_modes[]").
>
> This problem is clearly a problem with the gcc compiler on the box, namely gcc
> (Ubuntu/Linaro 4.6.3-1ubuntu5) 4.6.3. I had no success finding why the
> attributes were wrong, and finally settled on the following hack:
>
> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> index 99769d6c9f84..062bbe2b254a 100644
> --- a/drivers/gpu/drm/drm_edid.c
> +++ b/drivers/gpu/drm/drm_edid.c
> @@ -3272,6 +3272,7 @@ cea_mode_alternate_timings(u8 vic, struct drm_display_mode
> *mode)
> * get the other variants by simply increasing the
> * vertical front porch length.
> */
> +#ifndef CONFIG_PPC32
> BUILD_BUG_ON(cea_mode_for_vic(8)->vtotal != 262 ||
> cea_mode_for_vic(9)->vtotal != 262 ||
> cea_mode_for_vic(12)->vtotal != 262 ||
> @@ -3280,6 +3281,7 @@ cea_mode_alternate_timings(u8 vic, struct drm_display_mode
> *mode)
> cea_mode_for_vic(24)->vtotal != 312 ||
> cea_mode_for_vic(27)->vtotal != 312 ||
> cea_mode_for_vic(28)->vtotal != 312);
> +#endif
>
> if (((vic == 8 || vic == 9 ||
> vic == 12 || vic == 13) && mode->vtotal < 263) ||
>
> Disabling the build check allows me to build and test the post v5.5 versions.
>
> Larry
--
Ville Syrjälä
Intel
On 2/7/20 7:12 AM, Ville Syrjälä wrote:
> On Thu, Feb 06, 2020 at 04:46:52PM -0600, Larry Finger wrote:
>> When building post V5.5 on my PowerBook G4 Aluminum, the build failed with the
>> following error:
>
> It shouldn't be in 5.5
It isn't in 5.5, but in the transitional code between v5.5 and v5.6.0-rc1.
>
> There's a fix queued
> https://cgit.freedesktop.org/drm-misc/commit/?h=drm-misc-next-fixes&id=e1cf35b94c5fd122a8780587559fc6da9fc2dd12
>
> Does that work for you?
Yes it does fix the problem.
Thanks,
Larry