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

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Date:   Mon, 19 Feb 2018 11:44:22 +0100
From:   Mylène Josserand <mylene.josserand@...tlin.com>
To:     Maxime Ripard <maxime.ripard@...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, 19 Feb 2018 09:52:05 +0100
Maxime Ripard <maxime.ripard@...tlin.com> wrote:

> 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.

Okay, I will fix that in V4.

Mylène

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