Messages in this thread | | | Subject | Re: [PATCH] clocksource: arm_arch_timer: Support reading clock rate from a driver | From | Marc Zyngier <> | Date | Fri, 29 Jul 2016 11:31:44 +0100 |
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On 29/07/16 11:18, Mark Rutland wrote: > [adding Marc to Cc] > > On Fri, Jul 29, 2016 at 11:23:11AM +0200, Rafał Miłecki wrote: >> From: Rafał Miłecki <rafal@milecki.pl> >> >> On some devices using arch code for reading clock rate doesn't work. So >> far the only option was to specify clock-frequency in a DT. This works >> only if a clock frequency doesn't have to be calculated on runtime. >> >> On BCM53573 SoC (with Cortex-A7) there is ILP clock that needs its own >> driver. With this change we can query such clocks by using a standard: >> clocks = <&foo>; > > The clock for the architected timer(s) are supposed to be configured > before entering Linux. The clock-frequency property is at best a dodgy > workaround, and this is even worse. > > Please fix your firmware to configure and enabled this clock before > entering Linux, and to program CNTFRQ appropriately.
I'll add that failure to do so breaks other subsystems which do rely on CNTFRQ to be correctly programmed *on each CPU* (like KVM and Xen).
Please follow the requirements of the architecture and don't just paper over such a bug.
> As this path stands, NAK.
Seconded.
M. -- Jazz is not dead. It just smells funny...
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