linux-kernel - Re: [PATCH] perf/arm-cmn: fix regitster offset of CMN_MXP__CONNECT_INFO

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Date:   Mon, 3 Apr 2023 08:45:00 +0100
From:   Mark Rutland <mark.rutland@....com>
To:     Robin Murphy <robin.murphy@....com>
Cc:     Jing Zhang <renyu.zj@...ux.alibaba.com>,
        Ilkka Koskinen <ilkka@...amperecomputing.com>,
        Will Deacon <will@...nel.org>, linux-kernel@...r.kernel.org,
        linux-acpi@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-perf-users@...r.kernel.org,
        Shuai Xue <xueshuai@...ux.alibaba.com>,
        Zhuo Song <zhuo.song@...ux.alibaba.com>,
        Ruidong Tian <tianruidong@...ux.alibaba.com>
Subject: Re: [PATCH] perf/arm-cmn: fix regitster offset of
 CMN_MXP__CONNECT_INFO_P2-5

On Thu, Mar 30, 2023 at 11:34:22AM +0100, Robin Murphy wrote:
> On 2023-03-30 10:47, Jing Zhang wrote:
> > In the CMN700 specification, it is described that the address offset
> > of the mxp_device_connect_info_p0-5 register is 16'h8 + #{8*index}.
> > Therefore, the address offset of the CMN_MXP__CONNECT_INFO_P2-5 macro
> > defined in the code is wrong, which causes the cmn700 topology map
> > incorrect printed in debugfs.
> > 
> > So correct the address offset value to make the cmn700 topology map
> > correct in debugfs.
> > 
> > Fixes: 60d1504070c2 ("perf/arm-cmn: Support new IP features")
> 
> Ugh, these offsets are correct for CI-700, so strictly that commit is fine.
> What I failed to notice is that CMN-700 shuffled the mesh_port_connect_info
> registers out of the way, so it's commit 23760a014417 which should have
> added more handling for this difference.

I'm assuming that means that this patch breaks !CMN-700 ?

i.e. a more substantial fix is necessary, and it's not just a matter of
changing the Fixes tag.

Thanks,
Mark.

> 
> Thanks,
> Robin.
> 
> > Signed-off-by: Jing Zhang <renyu.zj@...ux.alibaba.com>
> > Signed-off-by: Ruidong Tian <tianruidong@...ux.alibaba.com>
> > ---
> >   drivers/perf/arm-cmn.c | 8 ++++----
> >   1 file changed, 4 insertions(+), 4 deletions(-)
> > 
> > diff --git a/drivers/perf/arm-cmn.c b/drivers/perf/arm-cmn.c
> > index 1deb61b..e9f844b 100644
> > --- a/drivers/perf/arm-cmn.c
> > +++ b/drivers/perf/arm-cmn.c
> > @@ -59,10 +59,10 @@
> >   /* XPs also have some local topology info which has uses too */
> >   #define CMN_MXP__CONNECT_INFO_P0	0x0008
> >   #define CMN_MXP__CONNECT_INFO_P1	0x0010
> > -#define CMN_MXP__CONNECT_INFO_P2	0x0028
> > -#define CMN_MXP__CONNECT_INFO_P3	0x0030
> > -#define CMN_MXP__CONNECT_INFO_P4	0x0038
> > -#define CMN_MXP__CONNECT_INFO_P5	0x0040
> > +#define CMN_MXP__CONNECT_INFO_P2	0x0018
> > +#define CMN_MXP__CONNECT_INFO_P3	0x0020
> > +#define CMN_MXP__CONNECT_INFO_P4	0x0028
> > +#define CMN_MXP__CONNECT_INFO_P5	0x0030
> >   #define CMN__CONNECT_INFO_DEVICE_TYPE	GENMASK_ULL(4, 0)
> >   /* PMU registers occupy the 3rd 4KB page of each node's region */