Hi Martin, Thanks for your inputs.
On Tue, 8 Oct 2019 at 23:11, Martin Blumenstingl <martin.blumensti...@googlemail.com> wrote: > > Hi Anand, > > On Tue, Oct 8, 2019 at 4:39 PM Anand Moon <linux.am...@gmail.com> wrote: > > > > Hi Kevin / Martin, > > > > On Tue, 8 Oct 2019 at 04:28, Kevin Hilman <khil...@baylibre.com> wrote: > > > > > > Martin Blumenstingl <martin.blumensti...@googlemail.com> writes: > > > > > > > On Mon, Oct 7, 2019 at 3:17 PM Anand Moon <linux.am...@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 > > > > > > > > > > Kevin, > > > > As per my understanding from the kernelci.org logs it seen that > > pwm-meson driver is requested more than once before it finally load the > > module. > > > > [0] > > https://storage.kernelci.org/next/master/next-20191008/arm64/defconfig/gcc-8/lab-baylibre/boot-meson-g12b-odroid-n2.txt > my understanding is that: > - the PWM regulator driver is built in (=y) > - the Meson PWM controller driver is built as module (=m) > - during boot the PWM regulator node is found and it has a matching > driver (built-in) > - the PWM regulator driver tries to find the PWM controller but cannot > find it yet (and reports "Failed to get PWM: -517") > - (this repeats a few times) > - then the filesystem / initramfs is loaded where the modules are located > - now the Meson PWM controller driver is loaded > - the PWM regulator driver tries to find the PWM controller -> now it found it > Thanks of this information. At my end on archlinux I also tried to update my initramfs to add support for *pwm-meson* to but it did not work for me. > > Hi Martin, > > > > I have tired your Martin's patch [1] and still the boot fails to move > > ahead with below logs. > > [1] https://lore.kernel.org/patchwork/patch/1034186/ > this patch only silences the "Failed to get PWM: -517" message > Mark didn't apply it back then because without that message it would > be harder to debug these issues > > > [ 1.543928] xhci-hcd xhci-hcd.0.auto: Host supports USB 3.0 SuperSpeed > > [ 1.550422] usb usb2: We don't know the algorithms for LPM for this > > host, disabling LPM. > > [ 1.558702] hub 2-0:1.0: USB hub found > > [ 1.562131] hub 2-0:1.0: 1 port detected > > [ 1.566206] dwc3-meson-g12a ffe09000.usb: switching to Device Mode > > [ 1.573252] meson-gx-mmc ffe05000.sd: Got CD GPIO > > [ 1.607405] hctosys: unable to open rtc device (rtc0) > > > > I have put some more prints in pwm-meson.c it fails to load the module > > as microsSD card is not completely initialized. > what makes you think that there's a problem with pwm-meson? > > can you please share a boot log with the command line parameter > "initcall_debug" [0]? > from Documentation/admin-guide/kernel-parameters.txt: > initcall_debug [KNL] Trace initcalls as they are executed. Useful > for working out where the kernel is dying during > startup. > Well I have tied to add this command *initcall_debug* to kernel command prompt. Here is the console log, but I did not see any init kernel timer logs Kernel command line: console=ttyAML0,115200n8 root=PARTUUID=45d7d61e-01 rw rootwait earlyprintk=serial,ttyAML0,115200 initcall_debug printk.time=y [0] https://pastebin.com/eBgJrSKe > you can also try the command line parameter "clk_ignore_unused" (it's > just a gut feeling: maybe a "critical" clock is being disabled because > it's not wired up correctly). > It look like some clk issue after I added the *clk_ignore_unused* to kernel command line it booted further to login prompt and cpufreq DVFS seem to be loaded. So I could conclude this is clk issue.below is the boot log Kernel command line: console=ttyAML0,115200n8 root=PARTUUID=45d7d61e-01 rw rootwait earlyprintk=serial,ttyAML0,115200 initcall_debug printk.time=y clk_ignore_unused [1] https://pastebin.com/Nsk0wZQJ > back when I was working out the CPU clock tree for the 32-bit SoCs I > had a bad parent clock in one of the muxes which resulted in sporadic > lockups if CPU DVFS was enabled. > you can try to disable CPU DVFS by dropping the OPP table and it's > references from the .dtsi > Yep yesterday my focus was to disable PWM feature and get boot up-to login prompt But not I have to look into clk feature. *Many thanks for your valuable inputs, I learned a lot of things.* > > Martin > > > [0] https://elinux.org/Initcall_Debug Best Regards -Anand
