Hi Neil, (adding Brian Kim, one of the Hardkernel developers to this conversation) On Fri, Jan 6, 2017 at 9:04 AM, Neil Armstrong <narmstrong@xxxxxxxxxxxx> wrote: > The current hardware is not able to run with all cores enabled at a > cluster frequency superior at 1536MHz. > But the currently shipped u-boot for the platform still reports an OPP > table with possible DVFS frequency up to 2GHz, and will not change since > the off-tree linux tree supports limiting the OPPs with a kernel parameter. > A recent u-boot change reports the boot-time DVFS around 100MHz and > the default performance cpufreq governor sets the maximum frequency. > Previous version of u-boot reported to be already at the max OPP and > left the OPP as is. > Nevertheless, other governors like ondemand could setup the max frequency > and make the system crash. > > This patch disables the DVFS clock and disables cpufreq. I don't have any Odroid-C2 board, but having to live without cpufreq sounds bad for the Odroid-C2 users. What would we expect from a kernel perspective (maybe the Hardkernel guys would adjust their u-boot instead of us adjusting to the behavior of one specific device? one solution that I could think of involves the "maxcpus" kernel parameter (see [0]), if this is not set u-boot should report a max CPU frequency of 1536MHz (= max frequency for 4 active cores). Based on the "maxcpus" value additional frequencies can be unlocked (this could be step-by-step if there are different frequencies for one core/two cores/etc.). However, I'd like to hear other opinions as well. Regards, Martin [0] http://lxr.free-electrons.com/source/Documentation/kernel-parameters.txt?v=4.8#L2163 -- 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
