From: will.deacon@arm•com (Will Deacon)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH v3 3/5] arm64: dts: Add support for Spreadtrum SC9836 SoC in dts and Makefile
Date: Fri, 28 Nov 2014 15:09:12 +0000 [thread overview]
Message-ID: <20141128150912.GI7144@arm.com> (raw)
In-Reply-To: <20141128150325.GC24370@e104818-lin.cambridge.arm.com>
On Fri, Nov 28, 2014 at 03:03:26PM +0000, Catalin Marinas wrote:
> On Fri, Nov 28, 2014 at 02:44:12PM +0000, Will Deacon wrote:
> > On Fri, Nov 28, 2014 at 02:35:32PM +0000, Mark Rutland wrote:
> > > On Fri, Nov 28, 2014 at 02:29:13PM +0000, Catalin Marinas wrote:
> > > > On Thu, Nov 27, 2014 at 01:43:09PM +0000, Mark Rutland wrote:
> > > > > On Thu, Nov 27, 2014 at 12:12:15PM +0000, Catalin Marinas wrote:
> > > > > > On Thu, Nov 27, 2014 at 11:50:43AM +0000, Mark Rutland wrote:
> > > > > > > On Tue, Nov 25, 2014 at 12:16:56PM +0000, Chunyan Zhang wrote:
> > > > > > > > +
> > > > > > > > + timer {
> > > > > > > > + compatible = "arm,armv8-timer";
> > > > > > > > + interrupts = <1 13 0xff01>,
> > > > > > > > + <1 14 0xff01>,
> > > > > > > > + <1 11 0xff01>,
> > > > > > > > + <1 10 0xff01>;
> > > > > > > > + clock-frequency = <26000000>;
> > > > > > >
> > > > > > > Please remove the clock-frequency property. Your FW should initialise
> > > > > > > CNTFRQ_EL0 on all CPUs (certainly PSCI 0.2 requires that you do this).
> > > > > >
> > > > > > Since this comes up regularly, I think we need a dev_warn() in the arch
> > > > > > timer driver when CONFIG_ARM64.
> > > > >
> > > > > I'll ack such a patch ;)
> > > >
> > > > How rude would this be?
> > > >
> > > > diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
> > > > index 2133f9d59d06..aaaf3433ccb9 100644
> > > > --- a/drivers/clocksource/arm_arch_timer.c
> > > > +++ b/drivers/clocksource/arm_arch_timer.c
> > > > @@ -371,7 +371,8 @@ arch_timer_detect_rate(void __iomem *cntbase, struct device_node *np)
> > > > return;
> > > >
> > > > /* Try to determine the frequency from the device tree or CNTFRQ */
> > > > - if (of_property_read_u32(np, "clock-frequency", &arch_timer_rate)) {
> > > > + if (IS_ENABLED(CONFIG_ARM64) ||
> > > > + of_property_read_u32(np, "clock-frequency", &arch_timer_rate)) {
> > > > if (cntbase)
> > > > arch_timer_rate = readl_relaxed(cntbase + CNTFRQ);
> > > > else
> > > >
> > >
> > > Probably too rude, given it doesn't WARN() the user.
> >
> > We override broken hardware ID registers all the time in device-tree without
> > dumping stack. Why is this any different?
>
> I'm not for dumping the stack, it's not relevant (just more noise).
>
> > > We should be extremely loud if we see the clock-frequency property on an
> > > arm64 system. Whether or not we should ignore the property is another
> > > matter.
> >
> > I don't really see the point in ignoring it. We will see broken hardware
> > [1] and this is just preventing ourselves from working around it. I'd much
> > rather have arch-timers with a "clock-frequence" property than have some
> > other timer instead because the kernel driver is being stubborn.
>
> I agree that sooner or later we'll need a workaround (we already did for
> Juno). My point is that many consider such overriding behaviour to be
> the default - i.e. don't bother writing any sane value in CNTFRQ in
> firmware at boot because Linux can cope without. It gets worse when
> companies develop their firmware long before starting to upstream kernel
> patches, so too late to fix it.
>
> > [1] A previous version of the Juno firmware, for example.
>
> What about CONFIG_BROKEN_FIRMWARE, default off?
I'd rather have a `firmware test' module, which could be as noisy as it
likes when it finds issues like this. It could also do things like fuzz the
PSCI interface.
> In the meantime I think we can be more tolerant:
>
> diff --git a/drivers/clocksource/arm_arch_timer.c b/drivers/clocksource/arm_arch_timer.c
> index 2133f9d59d06..87f67a93fcc7 100644
> --- a/drivers/clocksource/arm_arch_timer.c
> +++ b/drivers/clocksource/arm_arch_timer.c
> @@ -376,6 +376,8 @@ arch_timer_detect_rate(void __iomem *cntbase, struct device_node *np)
> arch_timer_rate = readl_relaxed(cntbase + CNTFRQ);
> else
> arch_timer_rate = arch_timer_get_cntfrq();
> + } else if (IS_ENABLED(CONFIG_ARM64)) {
> + pr_warn("Architected timer frequency overridden by DT (broken firmware?)\n");
> }
That looks sensible. It would be interesting to print the value of CNTFRQ
too.
Will
next prev parent reply other threads:[~2014-11-28 15:09 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <Sharkl64-v3>
2014-11-25 12:16 ` [PATCH v3 0/5] Add Spreadtrum Sharkl64 Platform support Chunyan Zhang
2014-11-25 12:16 ` [PATCH v3 1/5] Documentation: DT: Renamed of-serial.txt to 8250.txt Chunyan Zhang
2014-11-27 11:38 ` Mark Rutland
2014-11-27 12:08 ` Lyra Zhang
2014-11-25 12:16 ` [PATCH v3 2/5] Documentation: DT: Add bindings for Spreadtrum SoC Platform Chunyan Zhang
2014-11-25 12:52 ` Arnd Bergmann
2014-11-25 12:16 ` [PATCH v3 3/5] arm64: dts: Add support for Spreadtrum SC9836 SoC in dts and Makefile Chunyan Zhang
2014-11-27 11:50 ` Mark Rutland
2014-11-27 12:12 ` Catalin Marinas
2014-11-27 13:43 ` Mark Rutland
2014-11-28 14:29 ` Catalin Marinas
2014-11-28 14:35 ` Mark Rutland
2014-11-28 14:44 ` Will Deacon
2014-11-28 14:46 ` Mark Rutland
2014-11-28 14:59 ` Will Deacon
2014-11-28 14:50 ` Mark Brown
2014-11-28 15:03 ` Catalin Marinas
2014-11-28 15:09 ` Will Deacon [this message]
2014-11-28 16:40 ` Mark Rutland
2014-11-28 17:24 ` Catalin Marinas
2014-12-03 2:35 ` Orson Zhai
2014-12-03 9:16 ` Lyra Zhang
2014-11-25 12:16 ` [PATCH v3 4/5] arm64: Add support for Spreadtrum's Sharkl64 Platform in Kconfig and defconfig Chunyan Zhang
2014-11-25 12:57 ` Arnd Bergmann
2014-11-26 3:08 ` Lyra Zhang
[not found] ` <CAAfSe-uoXOJ8=agCFuBnXhj7nBBTskQ=8_jMtv_SAjor2gfO2w@mail.gmail.com>
2014-11-26 9:00 ` Arnd Bergmann
2014-11-25 12:16 ` [PATCH v3 5/5] tty/serial: Add Spreadtrum sc9836-uart driver support Chunyan Zhang
2014-11-25 20:03 ` Greg KH
2014-11-27 11:05 ` Lyra Zhang
2014-11-26 9:48 ` Tobias Klauser
2014-11-27 11:39 ` Lyra Zhang
2014-11-26 12:33 ` One Thousand Gnomes
2014-11-28 10:13 ` Orson Zhai
2014-11-26 18:29 ` Murali Karicheri
2014-11-27 11:59 ` Lyra Zhang
2014-11-27 12:57 ` Arnd Bergmann
2014-11-27 15:23 ` Lyra Zhang
2014-11-27 15:34 ` One Thousand Gnomes
2014-11-27 15:36 ` Arnd Bergmann
2014-12-03 9:17 ` Lyra Zhang
2014-12-03 9:50 ` Arnd Bergmann
2014-12-03 10:11 ` Russell King - ARM Linux
2014-12-03 12:08 ` Lyra Zhang
2014-12-03 12:15 ` Lyra Zhang
2014-11-25 12:57 ` [PATCH v3 0/5] Add Spreadtrum Sharkl64 Platform support Mark Brown
2014-11-25 12:59 ` Arnd Bergmann
2014-11-27 12:03 ` Mark Rutland
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