[PATCH v2 3/8] timer: orion-timer: Add timer_get_boot_us() for BOOTSTAGE support

Tony Dinh mibodhi at gmail.com
Sun Sep 4 04:36:03 CEST 2022


Hi Pali,

On Sat, Sep 3, 2022 at 6:08 PM Pali Rohár <pali at kernel.org> wrote:
>
> On Saturday 03 September 2022 17:38:01 Tony Dinh wrote:
> > Hi Pali,
> >
> > Is there a way to get the CPU frequency from the board upon start up?
> >
> > Thanks,
> > Tony
>
> Hello! Each SoC has either fixed CPU frequency or has some bits in SAR
> register which say on which frequency is CPU running. SAR bits are SoC
> specific and are documented either in Functional Specifications or in
> Hardware Specifications (both documents are available for free all
> 32-bit Marvell SoCs except 375 and 39x).

Thanks for the recap. I do remember you posted a patch for that detection.
https://lists.denx.de/pipermail/u-boot/2022-August/492034.html

Just want to make sure that the SAR register is the only way we can
detect it in u-boot. The Kirkwood 6192 SoC on this Pogo V4 board can
run at 200 Mhz and 800 Mhz with frequency scaling in Linux.

Thanks,
Tony


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