> -----Original Message----- > From: Thomas Gleixner [mailto:[email protected]] > Sent: Tuesday, July 04, 2017 10:10 PM > To: A.s. Dong > Cc: [email protected]; [email protected]; > [email protected]; [email protected]; Jacky Bai; Anson Huang; > [email protected]; [email protected]; Arnd Bergmann; Anson Huang > Subject: Re: [PATCH V3 2/2] timer: imx-tpm: add imx tpm timer support > > On Tue, 4 Jul 2017, Dong Aisheng wrote: > > > IMX Timer/PWM Module (TPM) supports both timer and pwm function while > > this patch only adds the timer support. PWM would be added later. > > > > The TPM counter, compare and capture registers are clocked by an > > asynchronous clock that can remain enabled in low power modes. > > > > Due to the possible bus fabric contention, the CNT write may take a > > few more cycles and we need add ETIME check in case current delta > > event program gets missed. > > > > Cc: Daniel Lezcano <[email protected]> > > Cc: Arnd Bergmann <[email protected]> > > Cc: Thomas Gleixner <[email protected]> > > Cc: Shawn Guo <[email protected]> > > Cc: Anson Huang <[email protected]> > > Cc: Bai Ping <[email protected]> > > Signed-off-by: Dong Aisheng <[email protected]> > > > > --- > > ChangeLog: > > v2->v3: > > * address all comments from Daniel Lezcano > > * add more explaination on ETIME check in commit message > > Actually the logic wants to be explained in a comment inside the function > as well. >
Good suggestion, will add them inside function as well. > I'm really impressed, that 10 years after we discovered the HPET disaster > (See comment in arch/x86/kernel/hpet.c::hpet_next_event) the same > hardware idiocy comes around again.... > Not quite sure but seems a bit different issue. The issue is still uncertain but the test shows it's related to fabric priority Configuration, if increase the A7 core priority higher than GPU, the issue is very hard to be seen. But we don't want to change the default priority, we use ETIME check to fix it. Probably I would be better add a FIXME prefix before the comments in code as well because it's still uncertain. Regards Dong Aisheng > Thanks, > > tglx >
