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

Hi Pali,

On Sat, Sep 3, 2022 at 6:08 PM Pali Rohár pali@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