On 22/12/15 23:42, Olof Johansson wrote: > On Tue, Dec 08, 2015 at 10:26:49AM +0000, Jon Hunter wrote: >> Enabling CPUFreq support for Tegra124 Chromebooks is causing the Tegra124 >> to hang when resuming from suspend. >> >> When CPUFreq is enabled, the CPU clock is changed from the PLLX clock to >> the DFLL clock during kernel boot. When resuming from suspend the CPU >> clock is temporarily changed back to the PLLX clock before switching back >> to the DFLL. If the DFLL is operating at a much lower frequency than the >> PLLX when we enter suspend, and so the CPU voltage rail is at a voltage >> too low for the CPUs to operate at the PLLX frequency, then the device >> will hang. >> >> Please note that the PLLX is used in the resume sequence to switch the CPU >> clock from the very slow 32K clock to a faster clock during early resume >> to speed up the resume sequence before the DFLL is resumed. >> >> Ideally, we should fix this by setting the suspend frequency so that it >> matches the PLLX frequency, however, that would be a bigger change. For >> now simply disable CPUFreq support for Tegra124 Chromebooks to avoid the >> hang when resuming from suspend. >> >> Fixes: 9a0baee960a7 ("ARM: tegra: Enable CPUFreq support for Tegra124 >> Chromebooks") >> >> Signed-off-by: Jon Hunter <jonathanh@xxxxxxxxxx> >> --- >> >> Please note that this fix is required for v4.4 > > Since I saw this mentioned on IRC, I applied it directly to the arm-soc > fixes branch. Thanks! Cheers Jon -- 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