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

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Message-ID: <bb01b83a-32cb-4efe-b9d6-06a4cf138b3b@arm.com>
Date: Wed, 20 Nov 2024 16:55:04 +0000
From: Robin Murphy <robin.murphy@....com>
To: Namhyung Kim <namhyung@...nel.org>, Will Deacon <will@...nel.org>,
 Mark Rutland <mark.rutland@....com>
Cc: Stephane Eranian <eranian@...gle.com>, LKML
 <linux-kernel@...r.kernel.org>, linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH] perf/arm-cmn: Fix arm_cmn_node_to_xp()

On 20/11/2024 4:41 pm, Namhyung Kim wrote:
> The portid_bits and deviceid_bits for XP type nodes are set in the
> arm_cmn_discover() and it's copied to others in arm_cmn_init_dtcs().
> But to get the XP from a node in the arm_cmn_init_dtcs(), it needs
> the {port,device}id_bits.
> 
> This makes arm-cmn PMU failing to count events on my setup.  What we
> need is the number of bits in total which is known by the cmn config.

Hmm, what about just moving the assignment to a point where it actually
makes more sense anyway?

Cheers,
Robin.

----->8-----
diff --git a/drivers/perf/arm-cmn.c b/drivers/perf/arm-cmn.c
index 397a46410f7c..30506c43776f 100644
--- a/drivers/perf/arm-cmn.c
+++ b/drivers/perf/arm-cmn.c
@@ -2178,8 +2178,6 @@ static int arm_cmn_init_dtcs(struct arm_cmn *cmn)
  			continue;
  
  		xp = arm_cmn_node_to_xp(cmn, dn);
-		dn->portid_bits = xp->portid_bits;
-		dn->deviceid_bits = xp->deviceid_bits;
  		dn->dtc = xp->dtc;
  		dn->dtm = xp->dtm;
  		if (cmn->multi_dtm)
@@ -2420,6 +2418,8 @@ static int arm_cmn_discover(struct arm_cmn *cmn, unsigned int rgn_offset)
  			}
  
  			arm_cmn_init_node_info(cmn, reg & CMN_CHILD_NODE_ADDR, dn);
+			dn->portid_bits = xp->portid_bits;
+			dn->deviceid_bits = xp->deviceid_bits;
  
  			switch (dn->type) {
  			case CMN_TYPE_DTC: