linux-kernel - Re: [PATCH 1/3] perf/arm-cmn: Fix DTC domain detection

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Message-ID: <f5881d86-eb14-a0da-b5f9-96a374a0bc7b@os.amperecomputing.com>
Date:   Fri, 20 Oct 2023 15:45:24 -0700 (PDT)
From:   Ilkka Koskinen <ilkka@...amperecomputing.com>
To:     Robin Murphy <robin.murphy@....com>
cc:     will@...nel.org, mark.rutland@....com,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        jeremy.linton@....com, ilkka@...amperecomputing.com,
        renyu.zj@...ux.alibaba.com
Subject: Re: [PATCH 1/3] perf/arm-cmn: Fix DTC domain detection


On Fri, 20 Oct 2023, Robin Murphy wrote:
> It transpires that dtm_unit_info is another register which got shuffled
> in CMN-700 without me noticing. Fix that in a way which also proactively
> fixes the fragile laziness of its consumer, just in case any further
> fields ever get added alongside dtc_domain.
>
> Fixes: 23760a014417 ("perf/arm-cmn: Add CMN-700 support")
> Signed-off-by: Robin Murphy <robin.murphy@....com>

Reviewed-by: Ilkka Koskinen <ilkka@...amperecomputing.com>

> ---
> drivers/perf/arm-cmn.c | 16 ++++++++++++++--
> 1 file changed, 14 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/perf/arm-cmn.c b/drivers/perf/arm-cmn.c
> index 913dc04b3a40..f1ac8d0cdb3b 100644
> --- a/drivers/perf/arm-cmn.c
> +++ b/drivers/perf/arm-cmn.c
> @@ -112,7 +112,9 @@
>
> #define CMN_DTM_PMEVCNTSR		0x240
>
> -#define CMN_DTM_UNIT_INFO		0x0910
> +#define CMN650_DTM_UNIT_INFO		0x0910
> +#define CMN_DTM_UNIT_INFO		0x0960
> +#define CMN_DTM_UNIT_INFO_DTC_DOMAIN	GENMASK_ULL(1, 0)
>
> #define CMN_DTM_NUM_COUNTERS		4
> /* Want more local counters? Why not replicate the whole DTM! Ugh... */
> @@ -2117,6 +2119,16 @@ static int arm_cmn_init_dtcs(struct arm_cmn *cmn)
> 	return 0;
> }
>
> +static unsigned int arm_cmn_dtc_domain(struct arm_cmn *cmn, void __iomem *xp_region)
> +{
> +	int offset = CMN_DTM_UNIT_INFO;
> +
> +	if (cmn->part == PART_CMN650 || cmn->part == PART_CI700)
> +		offset = CMN650_DTM_UNIT_INFO;
> +
> +	return FIELD_GET(CMN_DTM_UNIT_INFO_DTC_DOMAIN, readl_relaxed(xp_region + offset));
> +}
> +
> static void arm_cmn_init_node_info(struct arm_cmn *cmn, u32 offset, struct arm_cmn_node *node)
> {
> 	int level;
> @@ -2248,7 +2260,7 @@ static int arm_cmn_discover(struct arm_cmn *cmn, unsigned int rgn_offset)
> 		if (cmn->part == PART_CMN600)
> 			xp->dtc = 0xf;
> 		else
> -			xp->dtc = 1 << readl_relaxed(xp_region + CMN_DTM_UNIT_INFO);
> +			xp->dtc = 1 << arm_cmn_dtc_domain(cmn, xp_region);
>
> 		xp->dtm = dtm - cmn->dtms;
> 		arm_cmn_init_dtm(dtm++, xp, 0);
> -- 
> 2.39.2.101.g768bb238c484.dirty
>
>