On Wed, Jan 29, 2020 at 02:21:40PM +0100, Hans de Goede wrote: > On 29-01-2020 14:03, Andy Shevchenko wrote: > > On Tue, Jan 28, 2020 at 11:39:28PM +0100, Thomas Gleixner wrote: > > > Hans de Goede <hdegoede@xxxxxxxxxx> writes: ... > > > Typical crystal frequencies are 19.2, 24 and 25Mhz. > > > > Hans, I think Cherrytrail may be affected by this as the others. > > CHT AFAIK uses 19.2MHz xtal. > > Are you sure? I'm not. I may mixed this with PMC clock. > The first 5 entries of the CHT MSR_FSB_FREQ documentation exactly > match those of the BYT documentation (which has only 5 entries), > which suggests to me that CHT is also using a 25 MHz crystal. > > I can also make the other CHT only frequencies when assuming a 25 > MHz crystal, here is a bit from the patch I'm working on for this: > > /* > * Cherry Trail SDM MSR_FSB_FREQ frequencies to PLL settings map: > * 0000: 25 * 20 / 6 = 83.3333 MHz > * 0001: 25 * 4 / 1 = 100.0000 MHz > * 0010: 25 * 16 / 3 = 133.3333 MHz > * 0011: 25 * 28 / 6 = 116.6667 MHz > * 0100: 25 * 16 / 5 = 80.0000 MHz > * 0101: 25 * 56 / 15 = 93.3333 MHz > * 0110: 25 * 18 / 5 = 90.0000 MHz > * 0111: 25 * 32 / 9 = 88.8889 MHz > * 1000: 25 * 7 / 2 = 87.5000 MHz > */ > > 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. 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? -- With Best Regards, Andy Shevchenko
