[PATCH] perf/arm-cmn: Fix arm_cmn_node_to_xp()

[PATCH] perf/arm-cmn: Fix arm_cmn_node_to_xp()

[Namhyung Kim]

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.

Fixes: e79634b53e39 ("perf/arm-cmn: Refactor node ID handling. Again.")
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
 drivers/perf/arm-cmn.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/perf/arm-cmn.c b/drivers/perf/arm-cmn.c
index 49bd811c6fd6efdd..0e0d2f5cfdaea890 100644
--- a/drivers/perf/arm-cmn.c
+++ b/drivers/perf/arm-cmn.c
@@ -386,7 +386,7 @@ static struct arm_cmn_nodeid arm_cmn_nid(const struct arm_cmn_node *dn)
 static struct arm_cmn_node *arm_cmn_node_to_xp(const struct arm_cmn *cmn,
 					       const struct arm_cmn_node *dn)
 {
-	int id = dn->id >> (dn->portid_bits + dn->deviceid_bits);
+	int id = dn->id >> (cmn->num_xps == 1 ? 5 : 3);
 	int bits = arm_cmn_xyidbits(cmn);
 	int x = id >> bits;
 	int y = id & ((1U << bits) - 1);

base-commit: bf9aa14fc523d2763fc9a10672a709224e8fcaf4
-- 
2.47.0.338.g60cca15819-goog

Re: [PATCH] perf/arm-cmn: Fix arm_cmn_node_to_xp()

[Robin Murphy]

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:

Re: [PATCH] perf/arm-cmn: Fix arm_cmn_node_to_xp()

[Namhyung Kim]

Hello,

On Wed, Nov 20, 2024 at 04:55:04PM +0000, Robin Murphy wrote:
> 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?

Yep, this looks good to me too.  Do you want to me to resend this?

Thanks,
Namhyung

> 
> ----->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: