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Message-ID: <8ba831ae-4568-32af-3fd1-fd51a7c13dcd@linux.alibaba.com>
Date: Wed, 29 Mar 2023 19:53:56 +0800
From: Jing Zhang <renyu.zj@...ux.alibaba.com>
To: John Garry <john.g.garry@...cle.com>,
Ian Rogers <irogers@...gle.com>, Will Deacon <will@...nel.org>,
James Clark <james.clark@....com>,
Mike Leach <mike.leach@...aro.org>,
Leo Yan <leo.yan@...aro.org>,
Mark Rutland <mark.rutland@....com>,
Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
Jiri Olsa <jolsa@...nel.org>,
Namhyung Kim <namhyung@...nel.org>,
Adrian Hunter <adrian.hunter@...el.com>,
Ilkka Koskinen <ilkka@...amperecomputing.com>,
Robin Murphy <robin.murphy@....com>
Cc: linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
linux-perf-users@...r.kernel.org,
Shuai Xue <xueshuai@...ux.alibaba.com>,
Zhuo Song <zhuo.song@...ux.alibaba.com>
Subject: Re: [PATCH RFC 1/4] driver/perf: Add identifier sysfs file for CMN
在 2023/3/27 下午3:55, John Garry 写道:
> On 27/03/2023 03:46, Jing Zhang wrote:
>> To allow userspace to identify the specific implementation of the device,
>> add an "identifier" sysfs file.
>>
>> The perf tool can match the arm CMN metric through the identifier.
>>
>> Signed-off-by: Jing Zhang <renyu.zj@...ux.alibaba.com>
>> ---
>> drivers/perf/arm-cmn.c | 43 +++++++++++++++++++++++++++++++++++++++++++
>> 1 file changed, 43 insertions(+)
>>
>> diff --git a/drivers/perf/arm-cmn.c b/drivers/perf/arm-cmn.c
>> index c968986..0c138ad 100644
>> --- a/drivers/perf/arm-cmn.c
>> +++ b/drivers/perf/arm-cmn.c
>> @@ -1168,10 +1168,53 @@ static ssize_t arm_cmn_cpumask_show(struct device *dev,
>> .attrs = arm_cmn_cpumask_attrs,
>> };
>> +static ssize_t arm_cmn_identifier_show(struct device *dev,
>> + struct device_attribute *attr, char *buf)
>> +{
>> + struct arm_cmn *cmn = to_cmn(dev_get_drvdata(dev));
>> + if (cmn->model == CMN700) {
>> + return sysfs_emit(buf, "%s\n", "CMN700");
>
> Is it possible to have a pointer to this string in struct arm_cmn, such that we don't have to do this model to identifier lookup here? If-else chains like this are not scalable.
>
Will do.
> BTW, does this HW have some HW identifier register, like iidr? I think that using that may be preferable.
>
I didn't find the relevant identifier register.
Do Illka and Robin know that there is such a register that can identify different CMN versions? Looking forward to your suggestions.
>> + }
>> + else if (cmn->model == CMN650) {
>> + return sysfs_emit(buf, "%s\n", "CMN650");
>
> I'd use lowercase names
>
Ok.
>> + }
>> + else if (cmn->model == CMN600) {
>> + return sysfs_emit(buf, "%s\n", "CMN600");
>> + }
>> + else if (cmn->model == CI700) {
>> + return sysfs_emit(buf, "%s\n", "CI700");
>> + }
>> + return sysfs_emit(buf, "%s\n", "UNKNOWN");
>
> can we have a "is_visble" attr to just no show this when unknown?
>
Ok.
>> +}
>> +
>> +static umode_t arm_cmn_identifier_attr_visible(struct kobject *kobj,
>> + struct attribute *attr, int n)
>> +{
>> + struct device *dev = kobj_to_dev(kobj);
>> + struct arm_cmn *cmn = to_cmn(dev_get_drvdata(dev));
>> + if (cmn->model <= 0)
>> + return 0;
>> + return attr->mode;
>> +};
>> +
>> +static struct device_attribute arm_cmn_identifier_attr =
>> +__ATTR(identifier, 0444, arm_cmn_identifier_show, NULL);
>> +
>> +static struct attribute *arm_cmn_identifier_attrs[] = {
>> + &arm_cmn_identifier_attr.attr,
>> + NULL,
>
> nit: no need for trailing ',' on a sentinel
>
Ok, Will do.
>> +};
>> +
>> +static struct attribute_group arm_cmn_identifier_attr_group = {
>> + .attrs = arm_cmn_identifier_attrs,
>> + .is_visible = arm_cmn_identifier_attr_visible,
>> +};
>> +
>> static const struct attribute_group *arm_cmn_attr_groups[] = {
>> &arm_cmn_event_attrs_group,
>> &arm_cmn_format_attrs_group,
>> &arm_cmn_cpumask_attr_group,
>> + &arm_cmn_identifier_attr_group,
>> NULL
>> };
>>
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