Re: [PATCH v2 04/18] clocksource: Add ARM System timer driver

Maxime Coquelin
2015-03-02T16:53:17Z

Hi Paul, Uwe,

2015-02-20 22:48 GMT+01:00 Paul Bolle <pebolle@tiscali.nl>:
> On Fri, 2015-02-20 at 20:54 +0100, Uwe Kleine-König wrote:
>> On Fri, Feb 20, 2015 at 07:01:03PM +0100, Maxime Coquelin wrote:
>> > This patch adds clocksource support for ARMv7-M's System timer,
>> > also known as SysTick.
>> >
>> > Signed-off-by: Maxime Coquelin <mcoquelin.stm32@gmail.com>
>> > ---
>> > drivers/clocksource/Kconfig | 7 ++++
>> > drivers/clocksource/Makefile | 1 +
>> > drivers/clocksource/armv7m_systick.c | 78 ++++++++++++++++++++++++++++++++++++
>> > 3 files changed, 86 insertions(+)
>> > create mode 100644 drivers/clocksource/armv7m_systick.c
>> >
>> > diff --git a/drivers/clocksource/Kconfig b/drivers/clocksource/Kconfig
>> > index fc01ec2..fb6011e 100644
>> > --- a/drivers/clocksource/Kconfig
>> > +++ b/drivers/clocksource/Kconfig
>> > @@ -124,6 +124,13 @@ config CLKSRC_ARM_GLOBAL_TIMER_SCHED_CLOCK
>> > help
>> > Use ARM global timer clock source as sched_clock
>> >
>> > +config ARMV7M_SYSTICK
>> > + bool
>> I assume this symbol is enabled later in the series.
>
> Yes, I noticed it was selected in 14/18 ("ARM: Add STM32 family
> machine").
>
>> Would it make sense
>> to allow enabing the symbol for compile test coverage?
>>
>> > + select CLKSRC_OF if OF
>> What happens if ARMV7M_SYSTICK=y but OF=n? Doesn't the driver fail to
>> compile?
>>
>> > + select CLKSRC_MMIO
>> > + help
>> > + This options enables support for the ARMv7M system timer unit
>> the right spelling is ARMv7-M.
>
> This Kconfig entry has no prompt, so no one is going to see this text
> during make *config. Perhaps this should be made a comment. In that case
> the right spelling should still be used.

Yes, you are right.
Do you agree if I define it like this:

config ARMV7M_SYSTICK
bool "Clocksource driver for ARMv7-M System timer"
depends on OF && (CPU_V7M || COMPILE_TEST)
select CLKSRC_OF
select CLKSRC_MMIO
help
This options enables clocksource support for the ARMv7-M system
timer unit.

Thanks,
Maxime
>
> Thanks,
>
>
> Paul Bolle
>