From: Hans de Goede <hdegoede@redhat.com>
To: David Laight <David.Laight@ACULAB.COM>,
Peter Zijlstra <peterz@infradead.org>
Cc: Andy Shevchenko <andy@infradead.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>,
Vipul Kumar <vipulk0511@gmail.com>,
Vipul Kumar <vipul_kumar@mentor.com>,
Daniel Lezcano <daniel.lezcano@linaro.org>,
Srikanth Krishnakar <Srikanth_Krishnakar@mentor.com>,
Cedric Hombourger <Cedric_Hombourger@mentor.com>,
Len Brown <len.brown@intel.com>,
"x86@kernel.org" <x86@kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"stable@vger.kernel.org" <stable@vger.kernel.org>
Subject: Re: [PATCH 3/3] x86/tsc_msr: Make MSR derived TSC frequency more accurate
Date: Thu, 30 Jan 2020 17:04:15 +0100 [thread overview]
Message-ID: <8a8fd7a1-945e-4541-f0bc-387fae7c6822@redhat.com> (raw)
In-Reply-To: <01feee20ee5d4b83ab218c14fc35accb@AcuMS.aculab.com>
Hi,
On 30-01-2020 17:02, David Laight wrote:
> From: Hans de Goede
>> Sent: 30 January 2020 15:55
> ...
>>>> + * Moorefield (CHT MID) SDM MSR_FSB_FREQ frequencies simplified PLL model:
>>>> + * 0000: 100 * 5 / 6 = 83.3333 MHz
>>>> + * 0001: 100 * 1 / 1 = 100.0000 MHz
>>>> + * 0010: 100 * 4 / 3 = 133.3333 MHz
>>>> + * 0011: 100 * 1 / 1 = 100.0000 MHz
>>>
>>> Unless I'm going cross-eyed, that's 4 times the exact same table.
>>
>> Correct, except that the not listed values on the none Cherry Trail
>> table are undefined in the SDM, so we should probably deny them
>> (or as the old code was doing simply return 0).
>>
>> And at least the Moorefield (CHT MID) table is different for 0011, that
>> is again 100 MHz like 0001 instead of 116.6667 as it is for BYT and CHT.
>>
>> Note that the Merriefield (BYT MID) and Moorefield (CHT MID) values are
>> based on the old code I've not seen those values in the current latest
>> version of the SDM.
>
> I wonder if Moorefield:11 is an old typo?
I have no idea. Andy if you can find any docs on the MSR_FSB_FREQ values
for Merriefield (BYT MID) and Moorefield (CHT MID) that would be great,
if not I suggest we stick with what we have.
Regards,
Hans
next prev parent reply other threads:[~2020-01-30 16:04 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-30 11:52 [PATCH 1/3] x86/tsc_msr: Use named struct initializers Hans de Goede
2020-01-30 11:52 ` [PATCH 2/3] x86/tsc_msr: Fix MSR_FSB_FREQ mask for Cherry Trail devices Hans de Goede
2020-01-30 11:52 ` [PATCH 3/3] x86/tsc_msr: Make MSR derived TSC frequency more accurate Hans de Goede
2020-01-30 13:43 ` Peter Zijlstra
2020-01-30 15:21 ` David Laight
2020-01-30 15:56 ` Hans de Goede
2020-01-30 15:55 ` Hans de Goede
2020-01-30 16:02 ` David Laight
2020-01-30 16:04 ` Hans de Goede [this message]
2020-01-30 16:52 ` Andy Shevchenko
2020-01-30 16:59 ` Hans de Goede
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