linux-kernel - Re: [PATCH] perf/arm-cmn: Fix CMN_DTM_UNIT

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Message-ID: <d7c4f92f-a68c-26cf-896b-122158097622@arm.com>
Date:   Tue, 12 Sep 2023 09:08:00 +0100
From:   Robin Murphy <robin.murphy@....com>
To:     "guojinhui.liam" <guojinhui.liam@...edance.com>, will@...nel.org,
        mark.rutland@....com
Cc:     lizefan.x@...edance.com, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] perf/arm-cmn: Fix CMN_DTM_UNIT_INFO offset in CMN700

On 2023-09-12 05:03, guojinhui.liam wrote:
> The por_dtm_unit_info's offest is 0x0960 in CMN700 according to
> the CMN700 spec.
> 
> CMN700 spec link:
> https://developer.arm.com/documentation/102308/0302/?lang=en
> por_dtm_unit_info can be found in section [4.3.13.10 por_dtm_unit_info].
> 
> Signed-off-by: guojinhui.liam <guojinhui.liam@...edance.com>
> ---
>   drivers/perf/arm-cmn.c | 3 +++
>   1 file changed, 3 insertions(+)
> 
> diff --git a/drivers/perf/arm-cmn.c b/drivers/perf/arm-cmn.c
> index 913dc04b3a40..6f3fafee0ac9 100644
> --- a/drivers/perf/arm-cmn.c
> +++ b/drivers/perf/arm-cmn.c
> @@ -113,6 +113,7 @@
>   #define CMN_DTM_PMEVCNTSR		0x240
>   
>   #define CMN_DTM_UNIT_INFO		0x0910
> +#define CMN700_DTM_UNIT_INFO		0x0960
>   
>   #define CMN_DTM_NUM_COUNTERS		4
>   /* Want more local counters? Why not replicate the whole DTM! Ugh... */
> @@ -2247,6 +2248,8 @@ static int arm_cmn_discover(struct arm_cmn *cmn, unsigned int rgn_offset)
>   
>   		if (cmn->part == PART_CMN600)
>   			xp->dtc = 0xf;
> +		else if (cmn->part == PART_CMN700)
> +			xp->dtc = 1 << readl_relaxed(xp_region + CMN700_DTM_UNIT_INFO);

I'd prefer to fix this more thoroughly, since there are still potential 
issues with this code as-is. I already have that patch written[1], 
however it ended up spawning a couple more patches to revisit actually 
making meaningful use of the DTC domain information[2], which I've still 
been debugging, but I hope to post the whole series soon.

Thanks,
Robin.

[1] 
https://gitlab.arm.com/linux-arm/linux-rm/-/commit/e4216d99eed2cd951fc515f06ccf31672fb3f58d
[2] 
https://gitlab.arm.com/linux-arm/linux-rm/-/commits/cmn-dev?ref_type=heads

>   		else
>   			xp->dtc = 1 << readl_relaxed(xp_region + CMN_DTM_UNIT_INFO);
>