From: Anju T Sudhakar <anju@linux.vnet.ibm.com>
To: Michael Ellerman <mpe@ellerman.id.au>,
Stewart Smith <stewart@linux.vnet.ibm.com>,
Madhavan Srinivasan <maddy@linux.vnet.ibm.com>
Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
ego@linux.vnet.ibm.com, bsingharora@gmail.com,
benh@kernel.crashing.org, paulus@samba.org, anton@samba.org,
sukadev@linux.vnet.ibm.com, mikey@neuling.org, dja@axtens.net,
eranian@google.com, Hemant Kumar <hemant@linux.vnet.ibm.com>
Subject: Re: [PATCH v6 03/11] powerpc/powernv: Detect supported IMC units and its events
Date: Mon, 17 Apr 2017 13:38:10 +0530 [thread overview]
Message-ID: <8aacfd08-8007-172a-3e00-77a3c5bfdb08@linux.vnet.ibm.com> (raw)
In-Reply-To: <87o9w08rdx.fsf@concordia.ellerman.id.au>
Hi Michael,
On Thursday 13 April 2017 05:13 PM, Michael Ellerman wrote:
> Anju T Sudhakar <anju@linux.vnet.ibm.com> writes:
>> On Thursday 06 April 2017 02:07 PM, Stewart Smith wrote:
>>> Madhavan Srinivasan <maddy@linux.vnet.ibm.com> writes:
>>>> --- a/arch/powerpc/platforms/powernv/opal-imc.c
>>>> +++ b/arch/powerpc/platforms/powernv/opal-imc.c
>>>> @@ -33,6 +33,388 @@
>>> <snip>
>>>> +static void imc_pmu_setup(struct device_node *parent)
>>>> +{
>>>> + struct device_node *child;
>>>> + int pmu_count = 0, rc = 0;
>>>> + const struct property *pp;
>>>> +
>>>> + if (!parent)
>>>> + return;
>>>> +
>>>> + /* Setup all the IMC pmus */
>>>> + for_each_child_of_node(parent, child) {
>>>> + pp = of_get_property(child, "compatible", NULL);
>>>> + if (pp) {
>>>> + /*
>>>> + * If there is a node with a "compatible" field,
>>>> + * that's a PMU node
>>>> + */
>>>> + rc = imc_pmu_create(child, pmu_count);
>>>> + if (rc)
>>>> + return;
>>>> + pmu_count++;
>>>> + }
>>>> + }
>>>> +}
>>> This doesn't strike me as the right kind of structure, the presence of a
>>> compatible property really just says "hey, there's this device and it's
>>> compatible with these ways of accessing it".
>>>
>>> I'm guessing the idea behind having imc-nest-offset/size in a top level
>>> node is because it's common to everything under it and the aim is to not
>>> blow up the device tree to be enormous.
>>>
>>> So why not go after each ibm,imc-counters-nest compatible node under the
>>> top level ibm,opal-in-memory-counters node? (i'm not convinced that
>>> having ibm,ibmc-counters-nest versus ibm,imc-counters-core and
>>> ibm,imc-counters-thread as I see in the dts is correct though, as
>>> they're all accessed exactly the same way?)
>> The idea here is, we have one directory which contains common events
>> information for nest(same incase of core and thread), and one directory
>> for each nest(/core/thread) pmu.
>> So while parsing we need to make sure that the node which we are parsing
>> is the pmu node, not the node which contains the common event
>> information. We use the "compatible" property here for that purpose.
>> Because we don't have a compatible property for the node which contains
>> events info.
> That's a really bad hack.
>
> You can use the compatible property to detect the node you're looking
> for, but you need to look at the *value* of the property and check it's
> what you expect. Just checking that it's there is fragile.
>
> cheers
>
ok. I will rework this code.
Thanks,
Anju
next prev parent reply other threads:[~2017-04-17 8:08 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-03 14:54 [PATCH v6 00/11] IMC Instrumentation Support Madhavan Srinivasan
2017-04-03 14:54 ` [PATCH v6 01/11] powerpc/powernv: Data structure and macros definitions Madhavan Srinivasan
2017-04-04 1:48 ` Daniel Axtens
2017-04-05 4:22 ` Madhavan Srinivasan
2017-04-06 8:07 ` Stewart Smith
2017-04-06 8:39 ` Stewart Smith
2017-04-03 14:54 ` [PATCH v6 02/11] powerpc/powernv: Autoload IMC device driver module Madhavan Srinivasan
2017-04-04 0:58 ` Daniel Axtens
2017-04-05 6:34 ` Madhavan Srinivasan
2017-04-04 1:48 ` Daniel Axtens
2017-04-05 6:36 ` Madhavan Srinivasan
2017-04-06 7:04 ` Stewart Smith
2017-04-03 14:55 ` [PATCH v6 03/11] powerpc/powernv: Detect supported IMC units and its events Madhavan Srinivasan
2017-04-04 1:41 ` Daniel Axtens
2017-04-05 12:29 ` Madhavan Srinivasan
2017-04-06 8:37 ` Stewart Smith
2017-04-06 9:33 ` Anju T Sudhakar
2017-04-13 11:43 ` Michael Ellerman
2017-04-17 8:08 ` Anju T Sudhakar [this message]
2017-04-03 14:55 ` [PATCH v6 04/11] powerpc/perf: Add event attribute and group to IMC pmus Madhavan Srinivasan
2017-04-04 2:11 ` Daniel Axtens
2017-04-06 6:43 ` Madhavan Srinivasan
2017-04-03 14:55 ` [PATCH v6 05/11] powerpc/perf: Generic imc pmu event functions Madhavan Srinivasan
2017-04-04 3:55 ` Daniel Axtens
2017-04-03 14:55 ` [PATCH v6 06/11] powerpc/perf: IMC pmu cpumask and cpu hotplug support Madhavan Srinivasan
2017-04-04 4:33 ` Daniel Axtens
2017-04-06 8:04 ` Madhavan Srinivasan
2017-04-03 14:55 ` [PATCH v6 07/11] powerpc/powernv: Core IMC events detection Madhavan Srinivasan
2017-04-03 14:55 ` [PATCH v6 08/11] powerpc/perf: PMU functions for Core IMC and hotplugging Madhavan Srinivasan
2017-04-03 14:55 ` [PATCH v6 09/11] powerpc/powernv: Thread IMC events detection Madhavan Srinivasan
2017-04-03 14:55 ` [PATCH v6 10/11] powerpc/perf: Thread IMC PMU functions Madhavan Srinivasan
2017-04-03 14:55 ` [PATCH v6 11/11] powerpc/perf: Thread imc cpuhotplug support Madhavan Srinivasan
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