Messages in this thread | | | From | Kevin Hilman <> | Subject | Re: [RFCv1 5/5] arm64/ARM: configs: Change CONFIG_PWM_MESON from m to y | Date | Mon, 07 Oct 2019 15:57:59 -0700 |
| |
Martin Blumenstingl <martin.blumenstingl@googlemail.com> writes:
> On Mon, Oct 7, 2019 at 3:17 PM Anand Moon <linux.amoon@gmail.com> wrote: > [...] >> diff --git a/arch/arm64/configs/defconfig b/arch/arm64/configs/defconfig >> index c9a867ac32d4..72f6a7dca0d6 100644 >> --- a/arch/arm64/configs/defconfig >> +++ b/arch/arm64/configs/defconfig >> @@ -774,7 +774,7 @@ CONFIG_MPL3115=m >> CONFIG_PWM=y >> CONFIG_PWM_BCM2835=m >> CONFIG_PWM_CROS_EC=m >> -CONFIG_PWM_MESON=m >> +CONFIG_PWM_MESON=y > > some time ago I submitted a similar patch for the 32-bit SoCs > it turned that that pwm-meson can be built as module because the > kernel will run without CPU DVFS as long as the clock and regulator > drivers are returning -EPROBE_DEFER (-517)
On 64-bit SoCs, the kernel boots with PWM as a module also, but DVFS only works sometimes, and making it built-in fixes the problem. Actually, it doesn't fix, it just hides the problem, which is likely a race or timeout happening during deferred probing.
> did you check whether there's some other problem like some unused > clock which is being disabled at that moment? > I've been hunting weird problems in the past where it turned out that > changing kernel config bits changed the boot timing - that masked the > original problem
Right, I would definitely prefer to not make this built-in without a lot more information to *why* this is needed. In figuring that out, we'll probably find the race/timeout that's the root cause.
Kevin
| |