Hi All, On 03.08.2020 17:30, Marek Szyprowski wrote: > On 10.07.2020 21:11, Lukasz Luba wrote: >> The driver can operate in two modes relaying on devfreq monitoring >> mechanism which periodically checks the device status or it can use >> interrupts when they are provided by loaded Device Tree. The newly >> introduced module parameter can be used to choose between devfreq >> monitoring and internal interrupts without modifying the Device Tree. >> It also sets devfreq monitoring as default when the parameter is not set >> (also the case for default when the driver is not built as a module). >> >> Reported-by: Willy Wolff <willy.mh.wolff.ml@xxxxxxxxx> >> Signed-off-by: Lukasz Luba <lukasz.luba@xxxxxxx> > > I've got back from my holidays and noticed that in meantime this > commit got merged as commit 4fc9a0470d2d. It revealed that there is a > race between registering exynos5422-dmc driver and exynos-ppmu driver, > which can be observed sometimes as the following message and freeze on > Odroid XU3 with multi_v7_defconfig: > > [ 8.767708] exynos5-dmc 10c20000.memory-controller: couldn't probe > performance counters > > I will check this later why the EPROBE_DEFER error is not properly > propagated and why it causes a freeze. It looks that simply propagating return value from exynos5_counters_get() in exynos5_dmc_get_status() fixes the boot: # dmesg | grep dmc [ 8.838754] exynos-ppmu: new PPMU device registered 10d00000.ppmu (ppmu-event3-dmc0_0) [ 8.861344] exynos-ppmu: new PPMU device registered 10d10000.ppmu (ppmu-event3-dmc0_1) [ 8.868488] exynos5-dmc 10c20000.memory-controller: couldn't probe performance counters [ 8.874417] exynos-ppmu: new PPMU device registered 10d60000.ppmu (ppmu-event3-dmc1_0) [ 8.886612] exynos-ppmu: new PPMU device registered 10d70000.ppmu (ppmu-event3-dmc1_1) [ 9.396769] exynos5-dmc 10c20000.memory-controller: DMC initialized, in irq mode: 0 I'm still curious why it freezes if getting performance counters is not possible. Best regards -- Marek Szyprowski, PhD Samsung R&D Institute Poland
