On Tue, Oct 8, 2013 at 5:15 PM, Olof Johansson <olof@xxxxxxxxx> wrote: > [Adding Tony, who reported a mainline booting issue, and Sean who > helped me track this down] > > On Mon, Sep 23, 2013 at 7:15 AM, Mark Rutland <mark.rutland@xxxxxxx> wrote: >> On Sat, Sep 21, 2013 at 04:24:59PM +0100, Tomasz Figa wrote: >>> Hi Yuvaraj, >>> >>> On Wednesday 18 of September 2013 15:41:53 Yuvaraj Kumar C D wrote: >>> > Without the "clock-frequency" property in arch timer node, could able >>> > to see the below crash dump. >>> [snip] >>> > diff --git a/arch/arm/boot/dts/exynos5250.dtsi >>> > b/arch/arm/boot/dts/exynos5250.dtsi index 7d7cc77..668ce5d 100644 >>> > --- a/arch/arm/boot/dts/exynos5250.dtsi >>> > +++ b/arch/arm/boot/dts/exynos5250.dtsi >>> > @@ -96,6 +96,7 @@ >>> > <1 14 0xf08>, >>> > <1 11 0xf08>, >>> > <1 10 0xf08>; >>> > + clock-frequency = <24000000>; >>> >>> Shouldn't it rather come from some clock provided by some clock controller >>> instead? >>> >>> The frequency would be then retrieved using clk_get_rate() on a clock >>> received by clk_get(), specified in device tree using generic clock >>> bindings. >> >> If the bootloader has initialised the generic timer correctly, the >> CNTFRQ register should contain the clock frequency, independent of any >> external clock. > > So, we just sat here to bisect a problem on the Samsung Chromebook > where we hit exactly this problem. The read-only firmware on the > device does not set CNTFRQ at boot, so this fails. > > Apparantly the u-boot that comes with Arndale sets it, so I haven't > seen this error on that platform. > >> Having the bootloader set CNTFRQ is by far the preferable solution, it >> is architected for this purpose. > > Unfortunately there is now real hardware out there that needs this due > to firmware bugs / missing features, so there's little other choice. > :( > > I'll pick this patch up in the fixes branch for 3.12, unless someone > complains loudly. Perhaps the subject should say something about this only applying to exynos. Rob -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
