Re: Kconfig condition on BCM2835_TIMER (and others)

[Florian Fainelli]

On 2/4/25 15:31, Conor Dooley wrote:
> On Mon, Feb 03, 2025 at 01:44:05PM +0100, Etienne Buira wrote:
> > Resend with corrected email address.
> >
> > On Mon, Feb 03, 2025 at 01:39:33PM +0100, Etienne Buira wrote:
> > > Hi all,
> > >
> > > I want to build a kernel for Raspberry pi 4B, which, according to the
> > > dtb, has a bc2835-system-timer. This device is handled by
> > > drivers/clocksource/bcm2835_timer.c, which is built depending on
> > > CONFIG_BCM2835_TIMER.
> > >
> > > However, the config option is guarded by "if COMPILE_TEST" condition.
> > >
> > > Shouldn't that condition be ARM64 || COMPILE_TEST (ie be selectable on
> > > arm64 builds)?
>
> Perhaps, but I'd wonder why arm64 and arm32 are being treated differently.
> Florian, why's there no select on arm64 when the BCM2835 family option
> is enabled?

The Raspberry Pi 4B (Cortex-A72 CPU) primarily makes use of the ARM CPU 
local timer under drivers/clocksource/arm_arch_timer.c, therefore using 
bcm2835_timer.c is not necessary at all as a functional boot requirement.

There is no harm in enabling bcm2835_timer, and the arch_arm_timer.c 
rating being greater (400) than the bcm2835_timer (300), you will get 
the former to be selected anyway.

Feel free to submit a patch to enable the driver for ARM64.
--
Florian