Re: [v3] x86/tsc: Unset TSC_KNOWN_FREQ and TSC_RELIABLE flags on Intel Bay Trail SoC

From: Thomas Gleixner
Date: Wed Jan 29 2020 - 10:14:05 EST


Hans de Goede <hdegoede@xxxxxxxxxx> writes:
> On 29-01-2020 15:14, Andy Shevchenko wrote:
>>> The only one which is possibly suspicious here is this line:
>>>
>>> * 0111: 25 * 32 / 9 = 88.8889 MHz
>>>
>>> The SDM says 88.9 MHz for this one.

I trust math more than the SDM :)

>> Anyway it seems need to be fixed as well.
>>
>> Btw, why we are mentioning 20 / 6 and 28 / 6 when arithmetically
>> it's the same as 10 / 3 and 14 / 3?
>
> I copied the BYT values from Thomas' email and I guess he did not
> get around to simplifying them, I'll use the simplified versions
> for my patch.

Too tired, too lazy :)

Andy, can you please make sure that people inside Intel who can look
into the secrit documentation confirm what we are aiming for?

Ideally they should provide the X-tal frequency and the mult/div pair
themself :)

Thanks,

tglx