From: sudeep.holla@arm.com (Sudeep Holla)
To: linux-arm-kernel@lists.infradead.org
Subject: [RFC 1/1] ARM: print MHz in /proc/cpuinfo
Date: Wed, 8 Jun 2016 09:34:06 +0100 [thread overview]
Message-ID: <5757D87E.2080508@arm.com> (raw)
In-Reply-To: <1465333713-14339-2-git-send-email-jon.mason@broadcom.com>
On 07/06/16 22:08, Jon Mason wrote:
> Query the CPU core clock in the device tree to determine the core clock
> speed.
How do guarantee that it's the current frequency of the CPU ?
It doesn't even represent the mix or max frequency, so it's incorrect.
Some DTs have boot frequency in that entry.
> Output this clock rate in /proc/cpuinfo to match the output
> from other architectures. The output is intentionally patterned after
> the x86 output, to match existing (and possibly expected) convention.
>
> If any errors are encountered in querying the clock (or the speed is
> erroneously zero), nothing will be printed out. Thus any existing
> devices that do not have CPU clocks defined in the device tree will
> work as before.
>
What if they just don't have in DT but have DVFS support ?
Also whey do we need this support when the user-space can query the
CPUFreq sysfs which is more accurate and maintains the current running
frequency ?
--
Regards,
Sudeep
WARNING: multiple messages have this Message-ID (diff)
From: Sudeep Holla <sudeep.holla@arm.com>
To: Jon Mason <jon.mason@broadcom.com>
Cc: Russell King <linux@armlinux.org.uk>,
Sudeep Holla <sudeep.holla@arm.com>,
linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org
Subject: Re: [RFC 1/1] ARM: print MHz in /proc/cpuinfo
Date: Wed, 8 Jun 2016 09:34:06 +0100 [thread overview]
Message-ID: <5757D87E.2080508@arm.com> (raw)
In-Reply-To: <1465333713-14339-2-git-send-email-jon.mason@broadcom.com>
On 07/06/16 22:08, Jon Mason wrote:
> Query the CPU core clock in the device tree to determine the core clock
> speed.
How do guarantee that it's the current frequency of the CPU ?
It doesn't even represent the mix or max frequency, so it's incorrect.
Some DTs have boot frequency in that entry.
> Output this clock rate in /proc/cpuinfo to match the output
> from other architectures. The output is intentionally patterned after
> the x86 output, to match existing (and possibly expected) convention.
>
> If any errors are encountered in querying the clock (or the speed is
> erroneously zero), nothing will be printed out. Thus any existing
> devices that do not have CPU clocks defined in the device tree will
> work as before.
>
What if they just don't have in DT but have DVFS support ?
Also whey do we need this support when the user-space can query the
CPUFreq sysfs which is more accurate and maintains the current running
frequency ?
--
Regards,
Sudeep
next prev parent reply other threads:[~2016-06-08 8:34 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-06-07 21:08 [RFC 0/1] ARM: print MHz in /proc/cpuinfo Jon Mason
2016-06-07 21:08 ` Jon Mason
2016-06-07 21:08 ` [RFC 1/1] " Jon Mason
2016-06-07 21:08 ` Jon Mason
2016-06-08 8:34 ` Sudeep Holla [this message]
2016-06-08 8:34 ` Sudeep Holla
2016-06-08 19:31 ` Jon Mason
2016-06-08 19:31 ` Jon Mason
2016-06-09 9:09 ` Sudeep Holla
2016-06-09 9:09 ` Sudeep Holla
2016-06-09 17:36 ` Jon Mason
2016-06-09 17:36 ` Jon Mason
2016-06-07 22:18 ` [RFC 0/1] " Russell King - ARM Linux
2016-06-07 22:18 ` Russell King - ARM Linux
2016-06-07 22:58 ` Jon Mason
2016-06-07 22:58 ` Jon Mason
2016-07-02 23:58 ` Jon Masters
2016-07-02 23:58 ` Jon Masters
2016-07-03 16:54 ` Russell King - ARM Linux
2016-07-03 16:54 ` Russell King - ARM Linux
2016-07-03 18:49 ` Andrew Lunn
2016-07-03 18:49 ` Andrew Lunn
2016-07-03 19:10 ` Russell King - ARM Linux
2016-07-03 19:10 ` Russell King - ARM Linux
2016-07-18 10:02 ` Pavel Machek
2016-07-18 10:02 ` Pavel Machek
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=5757D87E.2080508@arm.com \
--to=sudeep.holla@arm.com \
--cc=linux-arm-kernel@lists.infradead.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.