linux-kernel - Re: [PATCH v3 6/7] arm: dts: sun8i: a83t: Fix undefined offset with virtual timer

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Message-ID: <20180219085205.jh6bcmbzcxqffkhk@flea.lan>
Date:   Mon, 19 Feb 2018 09:52:05 +0100
From:   Maxime Ripard <maxime.ripard@...tlin.com>
To:     Mylène Josserand <mylene.josserand@...tlin.com>
Cc:     wens@...e.org, linux@...linux.org.uk, robh+dt@...nel.org,
        mark.rutland@....com, devicetree@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        clabbe.montjoie@...il.com, thomas.petazzoni@...tlin.com,
        quentin.schulz@...tlin.com
Subject: Re: [PATCH v3 6/7] arm: dts: sun8i: a83t: Fix undefined offset with
 virtual timer

Hi,

On Mon, Feb 19, 2018 at 09:18:36AM +0100, Mylène Josserand wrote:
> The ARM architected timers use an offset between their physical and
> virtual counters. That offset should be configured by the bootloader
> in CNTVOFF.
> 
> However, the A83t bootloader fails to do so, and we end up with an
> undefined offset (which in our case is random), meaning that each CPU
> will have a different time, which isn't working very well.
> 
> Fix that by setting the arm,cpu-registers-not-fw-configured that will
> make Linux use the physical timers instead of the virtual ones. One
> possible side effect would be that the virtualization features would
> be disabled. However, due to the way the GIC has been integrated in
> the system, it is already unusable so we're effectively not losing any
> feature.
> 
> Signed-off-by: Mylène Josserand <mylene.josserand@...tlin.com>

One small nitpick on this one (and the previous one), arm in the
subject prefix should be uppercase.

Thanks!
Maxime

-- 
Maxime Ripard, Bootlin (formerly Free Electrons)
Embedded Linux and Kernel engineering
http://bootlin.com

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