[PATCH] clocksource/drivers/arm_arch_timer: Workaround bcm2712 broken EL2 virtual timer

[Florian Fainelli]

On 7/13/26 13:23, Marc Zyngier wrote:
> On Mon, 13 Jul 2026 17:15:35 +0100,
> Florian Fainelli <florian.fainelli at broadcom.com> wrote:
>>
>> On 7/10/26 01:09, Marc Zyngier wrote:
>>> It appears that the bcm2712 SoC found in the relatively popular
>>> RPi5 has a broken EL2 virtual timer.
>>>
>>> We do not know the reason why the timer isn't working (the timer
>>> is ticking, but the interrupt never fires), and the SoC vendor
>>> doesn't communicate on the reason why this isn't working, leaving
>>> users and maintainers in the dark.
>>>
>>> Paper over the issue by detecting the broken HW, falling back to
>>> the physical timer instead, and let the user know about it.
>>> Also taint the kernel as the machine is definitely not compliant
>>> with the spec, and we don't know what else is wrong with it.
>>>
>>> Reported-by: John <therealgraysky at proton.me>
>>> Reported-by: Daniel Drake <dan at reactivated.net>
>>> Reported-by: Marek Szyprowski <m.szyprowski at samsung.com>
>>> Signed-off-by: Marc Zyngier <maz at kernel.org>
>>> Cc: Florian Fainelli <florian.fainelli at broadcom.com>
>>> Cc: Daniel Lezcano <daniel.lezcano at linaro.org>
>>> Cc: Thomas Gleixner <tglx at linutronix.de>
>>> Cc: Mark Rutland <mark.rutland at arm.com>
>>
>> Acked-by: Florian Fainelli <florian.fainelli at broadcom.com>
>>
>> We know why now: the virtual interrupt timer line was never connected
>> in the first place because it was not clarified that it was a
>> requirement.
> 
> Dangling wires coming out of the CPUs don't ring any alarm bell at
> integration time? Amazing. Makes you wonder what else they forgot to
> connect...
> 
> Is there an erratum number that we can refer to for documentation
> purposes?

There is not one, we only have an internal bug tracker entry for this issue.
-- 
Florian