On Fri, 15 Jul 2016 12:38:54 +0200 Ondřej Jirman <megous@xxxxxxxxxx> wrote: > > If so, then yes, trying to switch to the 24MHz oscillator before > > applying the factors, and then switching back when the PLL is stable > > would be a nice solution. > > > > I just checked, and all the SoCs we've had so far have that > > possibility, so if it works, for now, I'd like to stick to that. > > It would need to be tested. U-boot does the change only once, while the > kernel would be doing it all the time and between various frequencies > and PLL settings. So the issues may show up with this solution too. I don't think this is a good idea: the CPU clock may be changed at any time with the CPUFreq governor. I don't see the system moving from 1008MHz to 24MHz and then to 1200MHz when some computation is needed! BTW, Ondřej, in my BPi M2+, I tried to change the CPU clock with your code at kernel start time from 792MHz to 1008MHz, but the hardware (arisc?) set an other value, and the system speed was lower than before (the PLL-CPUx register is 0x90031521 on boot, I want to set it to xxxx1410 and I read 0x91031f33 - sorry, I did not have a look at the CPU SD pattern). Do you know why? -- Ken ar c'hentañ | ** Breizh ha Linux atav! ** Jef | http://moinejf.free.fr/ -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
