diff mbox series

[Resend] perf/arm-cmn: Remove CMN-600 DTC domain special case

Message ID 67985e39f53b56385d79a4f1264cf7f9cacedb58.1742308248.git.robin.murphy@arm.com (mailing list archive)
State New
Headers show
Series [Resend] perf/arm-cmn: Remove CMN-600 DTC domain special case | expand

Commit Message

Robin Murphy March 18, 2025, 2:32 p.m. UTC
The special case for trying to infer the DTC domain for DTC-adjacent
nodes on CMN-600 is fragile and buggy - currently resulting in subtly
messed up DTC counter allocation - and the theoretical benefit it
offers to a tiny minority of use-cases arguably doesn't outweigh the
inconsistency it offers to others anyway. Just get rid of it.

Fixes: ab33c66fd8f1 ("perf/arm-cmn: Enable per-DTC counter allocation")
Signed-off-by: Robin Murphy <robin.murphy@arm.com>
---
 drivers/perf/arm-cmn.c | 7 -------
 1 file changed, 7 deletions(-)

Comments

Will Deacon March 18, 2025, 4:17 p.m. UTC | #1
Hi Robin,

On Tue, Mar 18, 2025 at 02:32:10PM +0000, Robin Murphy wrote:
> The special case for trying to infer the DTC domain for DTC-adjacent
> nodes on CMN-600 is fragile and buggy - currently resulting in subtly
> messed up DTC counter allocation - and the theoretical benefit it
> offers to a tiny minority of use-cases arguably doesn't outweigh the
> inconsistency it offers to others anyway. Just get rid of it.
> 
> Fixes: ab33c66fd8f1 ("perf/arm-cmn: Enable per-DTC counter allocation")
> Signed-off-by: Robin Murphy <robin.murphy@arm.com>
> ---
>  drivers/perf/arm-cmn.c | 7 -------
>  1 file changed, 7 deletions(-)

You've got "Resend" in the subject, but I can't seem to find the original
posting :/

Please can you point me at it? I just want to make sure that I'm not
missing patches, as you're unlikely to be the only person affected if
that is the case.

Cheers,

Will
Robin Murphy March 18, 2025, 4:40 p.m. UTC | #2
On 18/03/2025 4:17 pm, Will Deacon wrote:
> Hi Robin,
> 
> On Tue, Mar 18, 2025 at 02:32:10PM +0000, Robin Murphy wrote:
>> The special case for trying to infer the DTC domain for DTC-adjacent
>> nodes on CMN-600 is fragile and buggy - currently resulting in subtly
>> messed up DTC counter allocation - and the theoretical benefit it
>> offers to a tiny minority of use-cases arguably doesn't outweigh the
>> inconsistency it offers to others anyway. Just get rid of it.
>>
>> Fixes: ab33c66fd8f1 ("perf/arm-cmn: Enable per-DTC counter allocation")
>> Signed-off-by: Robin Murphy <robin.murphy@arm.com>
>> ---
>>   drivers/perf/arm-cmn.c | 7 -------
>>   1 file changed, 7 deletions(-)
> 
> You've got "Resend" in the subject, but I can't seem to find the original
> posting :/
> 
> Please can you point me at it? I just want to make sure that I'm not
> missing patches, as you're unlikely to be the only person affected if
> that is the case.

Sorry, forgot to explain below the cut - this is a resend from my end 
because I fat-fingered my LAKML alias the first time around, so I wasn't 
entirely sure whether you'd get it twice. I guess the error I got was 
actually from the SMTP server before it delivered anything, phew!

Thanks,
Robin.
diff mbox series

Patch

diff --git a/drivers/perf/arm-cmn.c b/drivers/perf/arm-cmn.c
index ef959e66db7c..582f0c0e1783 100644
--- a/drivers/perf/arm-cmn.c
+++ b/drivers/perf/arm-cmn.c
@@ -2166,13 +2166,6 @@  static int arm_cmn_init_dtcs(struct arm_cmn *cmn)
 
 	cmn->xps = arm_cmn_node(cmn, CMN_TYPE_XP);
 
-	if (cmn->part == PART_CMN600 && cmn->num_dtcs > 1) {
-		/* We do at least know that a DTC's XP must be in that DTC's domain */
-		dn = arm_cmn_node(cmn, CMN_TYPE_DTC);
-		for (int i = 0; i < cmn->num_dtcs; i++)
-			arm_cmn_node_to_xp(cmn, dn + i)->dtc = i;
-	}
-
 	for (dn = cmn->dns; dn->type; dn++) {
 		if (dn->type == CMN_TYPE_XP)
 			continue;