linux-kernel - Re: [PATCH 0/4] clocksource: Add standalone MMIO ARM arch timer driver

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Message-ID: <20250813-macho-snobbish-alpaca-ff07fa@sudeepholla>
Date: Wed, 13 Aug 2025 11:55:48 +0100
From: Sudeep Holla <sudeep.holla@....com>
To: Marc Zyngier <maz@...nel.org>
Cc: linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org,
	Sudeep Holla <sudeep.holla@....com>,
	Lorenzo Pieralisi <lpieralisi@...nel.org>,
	Hanjun Guo <guohanjun@...wei.com>,
	"Rafael J. Wysocki" <rafael@...nel.org>,
	Daniel Lezcano <daniel.lezcano@...aro.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Alexandru Elisei <alexandru.elisei@....com>,
	Mark Rutland <mark.rutland@....com>
Subject: Re: [PATCH 0/4] clocksource: Add standalone MMIO ARM arch timer
 driver

+Alexandru

On Thu, Aug 07, 2025 at 05:02:39PM +0100, Marc Zyngier wrote:
> For the past 10 years, both Mark and I have been lamenting about the
> sorry state of the badly named "arch_timer" driver, and about the way
> the MMIO part is intricately weaved into the system-register part.
> 
> The time has finally come to have a stab at it.
> 
> This small series simply creates a new timer driver for the MMIO arch
> timer, and only that. It is an actual driver, and not some kludge that
> has to run super early (that's what the per-CPU timers are for). This
> allows, in turn, a pretty large cleanup of the per-CPU driver, though
> there is more to come -- one thing at a time.
> 
> As an added bonus, we get a clocksource, which the original code
> didn't provide. Just in case it might be useful. The end-result is far
> more readable, and about 100 lines smaller.
> 

(Tested it on Juno R2 and FVP in both DT and ACPI boot)

Tested-by: Sudeep Holla <sudeep.holla@....com>
Reviewed-by: Sudeep Holla <sudeep.holla@....com>

Alexandru found it useful(avoids some unexpected hang IIUC) in his setup
based on bootwrapper which doesn't initialise MMIO timers.

-- 
Regards,
Sudeep