| Date | Fri, 8 May 2020 20:15:34 +0800 | From | Jiaxun Yang <> | Subject | Re: [PATCH v2 17/20] mips: Add udelay lpj numbers adjustment |
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On Wed, 6 May 2020 20:42:35 +0300 <Sergey.Semin@baikalelectronics.ru> wrote:
> From: Serge Semin <Sergey.Semin@baikalelectronics.ru> > > 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.Malahov@baikalelectronics.ru> > Signed-off-by: Alexey Malahov <Alexey.Malahov@baikalelectronics.ru> > Signed-off-by: Serge Semin <Sergey.Semin@baikalelectronics.ru> > Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> > Cc: Paul Burton <paulburton@kernel.org> > Cc: Ralf Baechle <ralf@linux-mips.org> > Cc: Arnd Bergmann <arnd@arndb.de> > Cc: Rob Herring <robh+dt@kernel.org> > Cc: linux-pm@vger.kernel.org > Cc: devicetree@vger.kernel.org
Reviewed-by: Jiaxun Yang <jiaxun.yang@flygoat.com>
That have been absent in MIPS kernel so long!
Thanks. > --- [...] --- Jiaxun Yang
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