Re: [PATCH v3 9/9] ARM: add initial support for Marvell Berlin SoCs

From: Sebastian Hesselbarth
Date: Thu Nov 07 2013 - 16:23:02 EST


On 11/07/2013 05:20 PM, Arnd Bergmann wrote:
On Thursday 07 November 2013, Sebastian Hesselbarth wrote:
Actually, IIRC smp_twd does not compile without SMP set, so the above
should at least be 'HAVE_ARM_TWD if SMP'. If you shrink MULTI_V7 down
to non-SMP cores, you can disable it and it will fail to compile.

If there are UP-systems for which TWD is the best clocksource, we should
probably fix the code to allow that configuration. IIRC there were already
patches recently in this area, maybe it's already solved.

I just tried barebox bootloader to use TWD as timer on berlin2cd and it
perfectly works, i.e. with time related commands I can see the timer
register decreasing. So the timer is available on this UP SoC.

As said before, compiling linux without CONFIG_SMP but with
CONFIG_HAVE_ARM_TWD gives:

warning: (SOC_OMAP5 && ARCH_ROCKCHIP && ARCH_SHMOBILE_MULTI && MACH_BERLIN_BG2 && MACH_BERLIN_BG2CD) selects HAVE_ARM_TWD which has unmet direct dependencies (SMP)

and

arch/arm/kernel/smp_twd.c: In function 'twd_local_timer_of_register':
arch/arm/kernel/smp_twd.c:391: error: 'setup_max_cpus' undeclared (first use in this function)
arch/arm/kernel/smp_twd.c:391: error: (Each undeclared identifier is reported only once
arch/arm/kernel/smp_twd.c:391: error: for each function it appears in.)
make[1]: *** [arch/arm/kernel/smp_twd.o] Error 1

I haven't looked deeper into this, but I guess it will not be hard
to make ARM_TWD independent of SMP.

Sebastian

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