Commit 2eca40a8 which went into 2.6.32-rc6 breaks compilation
for ipaq h3600 and probably other SA1100 machines when CONFIG_CPU_FREQ
is unset:
CC arch/arm/mach-sa1100/generic.o
arch/arm/mach-sa1100/generic.c:117: error: redefinition of 'cpufreq_get'
include/linux/cpufreq.h:299: error: previous definition of 'cpufreq_get'
was here
make[1]: *** [arch/arm/mach-sa1100/generic.o] Error 1
make: *** [arch/arm/mach-sa1100] Error 2
The problem is that before 2eca40a8 StrongArm aready had its own
version of cpufreq_get for CONFIG_CPU_FREQ=n case and now it clashed
with one introduced in 2eca40a8. Removing strongarm version will cure
compilation, but it then will break sa1100_fb driver in runtime, as it
blindly uses value which cpufreq_get returns for calculating pixel clock
divisor (see line 926 in drivers/video/sa1100fb.c) and 2eca40a8's cpufreq_get
returns 0.
One option would be to make sa1100_fb use hardcoded frequency 206.4MHz
(default on StrongARM CPUs) for CONFIG_CPU_FREQ=n case - see attached
patch. But I'm not sure if this is a proper fix.
Any ideas are welcome.
--
Best regards,
Dmitry "MAD" Artamonow
On Wed, Nov 11, 2009 at 10:23:15PM +0300, Dmitry Artamonow wrote:
> Commit 2eca40a8 which went into 2.6.32-rc6 breaks compilation
> for ipaq h3600 and probably other SA1100 machines when CONFIG_CPU_FREQ
> is unset:
I'm aware, I have a very large patch which fixes SA1100, but there's
other ARM machine classes which are similarly broken.
We've been around this loop before, where a change like this was
introduced and reverted. The kernel community seems set to constantly
repeat the same old mistakes time and time again.
> +#ifdef CONFIG_CPU_FREQ
> pcd = get_pcd(var->pixclock, cpufreq_get(0));
> +#else
> + pcd = get_pcd(var->pixclock, 206400);
> +#endif
This is just not acceptable, and could lead to LCD panel damage due
to wrong timings - not all platforms boot at 206.4MHz. Given that
it's far better that the kernel be obviously broken than silently
wrong while causing hardware damage.