Re: [PATCH V4 2/4] drivers/perf: imx_ddr: Add ddr performance counter support

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On Fri, Apr 05, 2019 at 09:34:38AM -0500, Zhi Li wrote:
> On Thu, Apr 4, 2019 at 6:17 AM Will Deacon <will.deacon@xxxxxxx> wrote:
> >
> > Hi Frank,
> >
> > On Fri, Feb 15, 2019 at 06:03:11PM +0000, Frank Li wrote:
> > > Add ddr performance monitor support for iMX8QXP
> > >
> > > There are 4 counters for ddr perfomance events.
> > > counter 0 is dedicated for cycles.
> > > you choose any up to 3 no cycles events.
> > >
> > > for example:
> > >
> > > perf stat -a -e ddr0/read-access/,ddr0/write-access/,ddr0/precharge/ ls
> > > perf stat -a -e ddr0/cycles/,ddr0/read-access/,ddr0/write-access/ ls
> >
> > Could you elaborate a bit on DDR_CAP_AXI_ID, please? Specifically, how
> > does the COUNTER_DPCR1 register work and what happens if I specify two
> > simultaneous events with different values in config1? I'm a little wary
> > of taking raw user input and throwing it straight into a device register!
> 
> I have not find better method to do that.
> bit 0-15: AXIID
> bit  16-31: AXID_MASK
> 
> Check condition AxID && AXI_MASKING == AXI_ID && AXI_MASKING

Hmm, that doesn't really answer my second question :(

  What happens if I specify two simultaneous events with different values
  in config1?

Will



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