On Thu, May 21, 2020 at 05:07:22PM +0300, Serge Semin wrote:
> Loops-per-jiffies is a special number which represents a number of
> noop-loop cycles per CPU-scheduler quantum - jiffies. As you
> understand aside from CPU-specific implementation it depends on
> the CPU frequency. So when a platform has the CPU frequency fixed,
> we have no problem and the current udelay interface will work
> just fine. But as soon as CPU-freq driver is enabled and the cores
> frequency changes, we'll end up with distorted udelay's. In order
> to fix this we have to accordinly adjust the per-CPU udelay_val
> (the same as the global loops_per_jiffy) number. This can be done
> in the CPU-freq transition event handler. We subscribe to that event
> in the MIPS arch time-inititalization method.
> 
> Co-developed-by: Alexey Malahov <alexey.mala...@baikalelectronics.ru>
> Signed-off-by: Alexey Malahov <alexey.mala...@baikalelectronics.ru>
> Signed-off-by: Serge Semin <sergey.se...@baikalelectronics.ru>
> Reviewed-by: Jiaxun Yang <jiaxun.y...@flygoat.com>
> Cc: Thomas Bogendoerfer <tsbog...@alpha.franken.de>
> Cc: Paul Burton <paulbur...@kernel.org>
> Cc: Ralf Baechle <r...@linux-mips.org>
> Cc: Arnd Bergmann <a...@arndb.de>
> Cc: Rob Herring <robh...@kernel.org>
> Cc: devicet...@vger.kernel.org
> ---
>  arch/mips/kernel/time.c | 70 +++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 70 insertions(+)

applied to mips-next.

Thomas.

-- 
Crap can work. Given enough thrust pigs will fly, but it's not necessarily a
good idea.                                                [ RFC1925, 2.3 ]

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