linux-kernel - Re: [v3] x86/tsc: Unset TSC_KNOWN_FREQ and TSC

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Message-ID: <37321319-e110-81f5-2488-cedf000da04d@redhat.com>
Date:   Fri, 24 Jan 2020 16:54:42 +0100
From:   Hans de Goede <hdegoede@...hat.com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Hans de Goede <hdegoede@...hat.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        vipul kumar <vipulk0511@...il.com>
Cc:     Daniel Lezcano <daniel.lezcano@...aro.org>,
        linux-kernel@...r.kernel.org, Stable <stable@...r.kernel.org>,
        Srikanth Krishnakar <Srikanth_Krishnakar@...tor.com>,
        Cedric Hombourger <Cedric_Hombourger@...tor.com>,
        x86@...nel.org, Len Brown <len.brown@...el.com>,
        Vipul Kumar <vipul_kumar@...tor.com>
Subject: Re: [v3] x86/tsc: Unset TSC_KNOWN_FREQ and TSC_RELIABLE flags on
 Intel Bay Trail SoC

Hi,

On 1/24/20 12:55 PM, Thomas Gleixner wrote:
> Hans,
> 
> Hans de Goede <hdegoede@...hat.com> writes:
>> On 1/24/20 9:35 AM, Thomas Gleixner wrote:
>>> Where does that number come from? Just math?
>>
>> Yes just math, but perhaps the Intel folks can see if they can find some
>> datasheet to back this up ?
> 
> Can you observe the issue on one of the machines in your zoo as well?

I haven't tried yet. Looking at the thread sofar the problem was noticed on
a system with a Celeron N2930, I don't have access to one of those, I
do have access to a system with a closely related N2840 I will give that
a try as well as see if I can reproduce this on one of the tablet
oriented Z3735x SoCs.

I'll report back when I have had a chance to test this.

Regards,

Hans