On Wed, Oct 9, 2013 at 1:25 AM, Mark Rutland <mark.rutland@xxxxxxx> wrote: > On Tue, Oct 08, 2013 at 11:15:47PM +0100, Olof Johansson 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. > > Ouch. That's a shame. > > A chained bootloader (like the KVM guys are using) should be able to set > CNTFRQ, so as long as any chained loader actually does that this won't > cause that to blow up... Yes, but we have cases where we want to be able to boot without a chained u-boot as well. >> 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. >> :( > > Indeed :( > >> >> I'll pick this patch up in the fixes branch for 3.12, unless someone >> complains loudly. > > Could you please add a note to the dts regarding why we actually need > this? It would be nice to maintain the impression that this is not the > preferred way of doing things... s/dts/dtsi/, yes I can do that. Hopefully with that we won't get too much automated copy and paste to other platforms. It looks like current upstream u-boot got the timer enablement patches merged together with HYP support, which explains why I didn't see this on Arndale since it has a forked version of u-boot from Linaro somewhere. -Olof -- 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
