Messages in this thread | | | Subject | Re: [PATCH v2 2/2] memory: samsung: exynos5422-dmc: Add module param to control IRQ mode | From | Lukasz Luba <> | Date | Tue, 4 Aug 2020 09:06:01 +0100 |
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Hi Marek,
On 8/3/20 4:35 PM, Marek Szyprowski wrote: > 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@gmail.com> >>> Signed-off-by: Lukasz Luba <lukasz.luba@arm.com> >> >> 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 >
Thank you for investigating this issue. Indeed, it's odd why it freezes. I've seen you patch with the fix.
Regards, Lukasz
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