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Message-ID: <1417055224.12707.24.camel@mtksdaap41>
Date: Thu, 27 Nov 2014 10:27:04 +0800
From: Yingjoe Chen <yingjoe.chen@...iatek.com>
To: Doug Anderson <dianders@...omium.org>
CC: Sonny Rao <sonnyrao@...omium.org>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>,
Mark Rutland <Mark.Rutland@....com>,
"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
Lorenzo Pieralisi <lorenzo.pieralisi@....com>,
"pawel.moll@....com" <pawel.moll@....com>,
"ijc+devicetree@...lion.org.uk" <ijc+devicetree@...lion.org.uk>,
Marc Zyngier <marc.zyngier@....com>,
Catalin Marinas <catalin.marinas@....com>,
Daniel Lezcano <daniel.lezcano@...aro.org>,
Will Deacon <will.deacon@....com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"robh+dt@...nel.org" <robh+dt@...nel.org>,
"galak@...eaurora.org" <galak@...eaurora.org>,
Sudeep Holla <Sudeep.Holla@....com>,
Olof Johansson <olof@...om.net>,
Nathan Lynch <Nathan_Lynch@...tor.com>,
Thomas Gleixner <tglx@...utronix.de>,
Stephen Boyd <sboyd@...eaurora.org>
Subject: Re: [PATCH v4] clocksource: arch_timer: Allow the device tree to
specify uninitialized timer registers
Hi,
On Wed, 2014-11-26 at 08:14 -0800, Doug Anderson wrote:
> Yingjoe,
>
> On Wed, Nov 26, 2014 at 6:41 AM, Yingjoe Chen <yingjoe.chen@...iatek.com> wrote:
> > Sorry for the (very) late reply.
> > I just realize today MT8135 need this and the other patch [1] to boot
> > SMP correctly. I've applied both patches and they works fine. Thanks :)
>
> Excellent. It's helpful to include a Tested-by: tag in your email.
> You'd have a line with just "Tested-by: Yingjoe Chen
> <yingjoe.chen@...iatek.com>"
sure, here's my tested-by for the 2 patches
Tested-by: Yingjoe Chen <yingjoe.chen@...iatek.com>
I'll remember to add it next time :)
> > However, I'm not sure if we really need to add new property.
> > arm_arch_timer driver will only use virtual timer when virtual PPI
> > interrupt is provided, so the following patch to timer dtsi will also
> > works. I think if the firmware doesn't support virtual timer, it make
> > sense to not supply virtual interrupt.
> >
> > timer {
> > compatible = "arm,armv7-timer";
> > interrupts = <GIC_PPI 13 IRQ_TYPE_LEVEL_LOW>,
> > - <GIC_PPI 14 IRQ_TYPE_LEVEL_LOW>,
> > - <GIC_PPI 11 IRQ_TYPE_LEVEL_LOW>,
> > - <GIC_PPI 10 IRQ_TYPE_LEVEL_LOW>;
> > + <GIC_PPI 14 IRQ_TYPE_LEVEL_LOW>;
> > clock-frequency = <13000000>;
> > };
>
> Once you have Sonny's patch then I believe that the above would work.
> However we rejected something like this because device tree is
> supposed to describe the hardware. The hardware really does provide
> the virtual timer interrupts and they really are at PPI 11 and PPI 10.
> It's just that firmware doesn't handle things properly so they can't
> be used.
>
> NOTE: If we add the "arm,cpu-registers-not-fw-configured" to the
> device tree and firmware actually works out how to configure things
> (like if somehow has firmware that has a hypervisor) then it can
> easily remove this device tree property before calling through to the
> kernel. It would be much harder for the firmware to add back in the
> "PPI 11" and "PPI 10" entries to the timer.
>
> -Doug
I see your point, that's good for me then.
Thanks.
Joe.C
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