Re: [PATCH v2] perf: imx9_perf: Introduce AXI filter version to refactor the driver and better extension

Xu Yang
2024-12-12T04:56:59Z

On Wed, Dec 11, 2024 at 09:56:38PM +0000, Will Deacon wrote:
> On Wed, Dec 11, 2024 at 01:35:16PM +0800, Xu Yang wrote:
> > On Tue, Dec 10, 2024 at 01:37:32PM +0000, Will Deacon wrote:
> > > On Tue, Dec 10, 2024 at 10:02:12AM +0800, Xu Yang wrote:
> > > > On Mon, Dec 09, 2024 at 03:44:20PM +0000, Will Deacon wrote:
> > > > > On Mon, Nov 25, 2024 at 06:43:38PM +0800, Xu Yang wrote:
> > > > > > The imx93 is the first supported DDR PMU that supports read transaction,
> > > > > > write transaction and read beats events which corresponding respecitively
> > > > > > to counter 2, 3 and 4.
> > > > > >
> > > > > > However, transaction-based AXI match has low accuracy when get total bits
> > > > > > compared to beats-based. And imx93 doesn't assign AXI_ID to each master.
> > > > > > So axi filter is not used widely on imx93. This could be regards as AXI
> > > > > > filter version 1.
> > > > > >
> > > > > > To improve the AXI filter capability, imx95 supports 1 read beats and 3
> > > > > > write beats event which corresponding respecitively to counter 2-5. imx95
> > > > > > also detailed AXI_ID allocation so that most of the master could be count
> > > > > > individually. This could be regards as AXI filter version 2.
> > > > > >
> > > > > > This will introduce AXI filter version to refactor the driver and support
> > > > > > better extension, such as coming imx943.
> > > > > >
> > > > > > Signed-off-by: Xu Yang <xu.yang_2@nxp.com>
> > > > > >
> > > > > > ---
> > > > > > Changes in v2:
> > > > > > - modify subject
> > > > > > - add comments for AXI_FILTER version
> > > > > > - type -> filter_ver
> > > > > > ---
> > > > > > drivers/perf/fsl_imx9_ddr_perf.c | 33 ++++++++++++++++++++++++--------
> > > > > > 1 file changed, 25 insertions(+), 8 deletions(-)
> > >
> > > [...]
> > >
> > > > > > @@ -624,11 +641,11 @@ static int ddr_perf_event_add(struct perf_event *event, int flags)
> > > > > > hwc->idx = counter;
> > > > > > hwc->state |= PERF_HES_STOPPED;
> > > > > >
> > > > > > - if (is_imx93(pmu))
> > > > > > + if (axi_filter_v1(pmu))
> > > > > > /* read trans, write trans, read beat */
> > > > > > imx93_ddr_perf_monitor_config(pmu, event_id, counter, cfg1, cfg2);
> > > > >
> > > > > Hmm, doesn't this change mean we now enable this for imx91 as well? My
> > > > > reading of the commit message is that imx93 was the first chip which
> > > > > supports this.
> > > >
> > > > Yes, it's enabled for imx91 too. In fact, imx91 is compatible with imx93.
> > > > They use same configuration for axi filter.
> > >
> > > Ok, but my worry is that the above code looks like userspace now _must_
> > > provide valid values for the config1 (axi_id) and config2 (axi_mask)
> > > fields on imx91, whereas before I think they were ignored by the driver.
> > >
> > > In fact, without this change, how were the PMCFGn registers configured
> > > on imx91? It looks to me like they were left uninitialised...
> >
> > Before this change, PMCFGn registers are indeed not configured on imx91.
> > However, they should be configured as imx93. I notice this thing when
> > make this patch. First thing I tried is to add is_imx91(), then check it
> > and is_imx93() by "||" operator. However, this way seems not scalable as
> > more imx9x Soc comes out. Basically, AXI filter version will keep at V2
> > unless big changes due to new features. However, perf tool need export
> > correct MetricName via identifier in sysfs. So I made this patch, then
> > PMCFGn will be configured based on axi filter version rather than pmu
> > name.
>
> Gotcha. But that means this is a fix, right? The commit message doesn't
> really indicate that and we probably want a Fixes: tag to indicate how
> far it should be backported.
>
> Please can you send a v3 with that so I can apply it?

Sure.

Thanks,
Xu Yang