From: Shaokun Zhang <zhangshaokun@hisilicon.com> To: John Garry <john.garry@huawei.com>, Will Deacon <will@kernel.org>, "Rob Herring" <robh@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com>, <devicetree@vger.kernel.org>, "Joakim Zhang" <qiangqing.zhang@nxp.com>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, NXP Linux Team <linux-imx@nxp.com>, Shawn Guo <shawnguo@kernel.org>, "moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" <linux-arm-kernel@lists.infradead.org> Subject: Re: [PATCH V1 RESEND 1/3] perf/imx_ddr: Add system PMU identifier for userspace Date: Thu, 28 May 2020 09:35:13 +0800 [thread overview] Message-ID: <36a5bf0c-fcf5-ad74-b5ee-1b4502705aec@hisilicon.com> (raw) In-Reply-To: <51aa7cbc-0ce2-b96d-b056-fcc6013ccecf@huawei.com> Hi, On 2020/5/27 22:34, John Garry wrote: >>>>> >>>>> I also really dislike this. What's the preferred way to identify the SoC >>>>> from userspace? >>>> >>>> /proc/cpuinfo? ;) >>> >>> The *SoC*! >>> >>>> For an non-firmware specific case, I'd say soc_device should be. I'd >>>> guess ACPI systems don't use it and for them it's dmidecode typically. >>>> The other problem I have with soc_device is it is optional. >>> >> >> Hi Will, >> >>> John -- what do you think about using soc_device to expose this information, >>> with ACPI systems using DMI data instead? >> >> Generally I don't think that DMI is reliable, and I saw this as the least preferred choice. I'm looking at the sysfs DMI info for my dev board, and I don't even see anything like a SoC identifier. >> >> As for the event_source device sysfs identifier file, it would not always contain effectively the same as the SoC ID. >> >> Certain PMUs which I'm interested in plan to have probe-able identification info available in future. >> > > BTW, Shaokun now tells me that the HiSi uncore PMU HW have such registers to identify the implementation. I didn't know. > Right, we have this register which shows the PMU version. Thanks, Shaokun > So we could add that identifier file for those PMUs as proof-of-concept, exposing that register. > > As for other PMUs which I'm interested in, again, future versions should have such registers to self-identify. > > So using something derived from the DT compat string would hopefully be the uncommon case. > > Cheers, > John > > . >
WARNING: multiple messages have this Message-ID (diff)
From: Shaokun Zhang <zhangshaokun@hisilicon.com> To: John Garry <john.garry@huawei.com>, Will Deacon <will@kernel.org>, "Rob Herring" <robh@kernel.org> Cc: Mark Rutland <mark.rutland@arm.com>, devicetree@vger.kernel.org, Joakim Zhang <qiangqing.zhang@nxp.com>, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, NXP Linux Team <linux-imx@nxp.com>, Shawn Guo <shawnguo@kernel.org>, "moderated list:ARM/FREESCALE IMX / MXC ARM ARCHITECTURE" <linux-arm-kernel@lists.infradead.org> Subject: Re: [PATCH V1 RESEND 1/3] perf/imx_ddr: Add system PMU identifier for userspace Date: Thu, 28 May 2020 09:35:13 +0800 [thread overview] Message-ID: <36a5bf0c-fcf5-ad74-b5ee-1b4502705aec@hisilicon.com> (raw) In-Reply-To: <51aa7cbc-0ce2-b96d-b056-fcc6013ccecf@huawei.com> Hi, On 2020/5/27 22:34, John Garry wrote: >>>>> >>>>> I also really dislike this. What's the preferred way to identify the SoC >>>>> from userspace? >>>> >>>> /proc/cpuinfo? ;) >>> >>> The *SoC*! >>> >>>> For an non-firmware specific case, I'd say soc_device should be. I'd >>>> guess ACPI systems don't use it and for them it's dmidecode typically. >>>> The other problem I have with soc_device is it is optional. >>> >> >> Hi Will, >> >>> John -- what do you think about using soc_device to expose this information, >>> with ACPI systems using DMI data instead? >> >> Generally I don't think that DMI is reliable, and I saw this as the least preferred choice. I'm looking at the sysfs DMI info for my dev board, and I don't even see anything like a SoC identifier. >> >> As for the event_source device sysfs identifier file, it would not always contain effectively the same as the SoC ID. >> >> Certain PMUs which I'm interested in plan to have probe-able identification info available in future. >> > > BTW, Shaokun now tells me that the HiSi uncore PMU HW have such registers to identify the implementation. I didn't know. > Right, we have this register which shows the PMU version. Thanks, Shaokun > So we could add that identifier file for those PMUs as proof-of-concept, exposing that register. > > As for other PMUs which I'm interested in, again, future versions should have such registers to self-identify. > > So using something derived from the DT compat string would hopefully be the uncommon case. > > Cheers, > John > > . > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2020-05-28 1:35 UTC|newest] Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-05-12 7:31 [PATCH V1 RESEND 0/3] perf/imx_ddr: Add system PMU support Joakim Zhang 2020-05-12 7:31 ` Joakim Zhang 2020-05-12 7:31 ` [PATCH V1 RESEND 1/3] perf/imx_ddr: Add system PMU identifier for userspace Joakim Zhang 2020-05-12 7:31 ` Joakim Zhang 2020-05-19 18:51 ` Rob Herring 2020-05-19 18:51 ` Rob Herring 2020-05-20 2:56 ` Joakim Zhang 2020-05-20 2:56 ` Joakim Zhang 2020-05-20 15:10 ` Rob Herring 2020-05-20 15:10 ` Rob Herring 2020-05-20 7:33 ` Will Deacon 2020-05-20 7:33 ` Will Deacon 2020-05-20 15:23 ` Rob Herring 2020-05-20 15:23 ` Rob Herring 2020-05-21 13:04 ` Will Deacon 2020-05-21 13:04 ` Will Deacon 2020-05-21 14:00 ` John Garry 2020-05-21 14:00 ` John Garry 2020-05-27 14:34 ` John Garry 2020-05-27 14:34 ` John Garry 2020-05-28 1:35 ` Shaokun Zhang [this message] 2020-05-28 1:35 ` Shaokun Zhang 2020-05-21 13:26 ` Mark Rutland 2020-05-21 13:26 ` Mark Rutland 2020-05-21 14:16 ` John Garry 2020-05-21 14:16 ` John Garry 2020-05-12 7:31 ` [PATCH V1 RESEND 2/3] bindings/perf/imx-ddr: update compatible string Joakim Zhang 2020-05-12 7:31 ` Joakim Zhang 2020-05-19 18:47 ` Rob Herring 2020-05-19 18:47 ` Rob Herring 2020-07-15 11:03 ` John Garry 2020-07-15 11:03 ` John Garry 2020-07-20 8:57 ` Joakim Zhang 2020-07-20 8:57 ` Joakim Zhang 2020-05-12 7:31 ` [PATCH V1 RESEND 3/3] arch: arm64: imx8mq/m/n: remove unused " Joakim Zhang 2020-05-12 7:31 ` Joakim Zhang
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