On 5/20/22 11:42 AM, Chen-Yu Tsai wrote: > On Fri, May 20, 2022 at 9:28 AM Chanwoo Choi <cw00.choi@xxxxxxxxxxx> wrote: >> >> Hi Kevin, Chen-Yu, >> >> On 5/20/22 3:25 AM, Kevin Hilman wrote: >>> Chen-Yu Tsai <wenst@xxxxxxxxxxxx> writes: >>> >>>> n Wed, May 18, 2022 at 8:03 AM Kevin Hilman <khilman@xxxxxxxxxx> wrote: >>>>> >>>>> Kevin Hilman <khilman@xxxxxxxxxx> writes: >>>>> >>>>>> Chen-Yu Tsai <wenst@xxxxxxxxxxxx> writes: >>>>>> >>>>>>> On Mon, May 16, 2022 at 8:43 AM Roger Lu <roger.lu@xxxxxxxxxxxx> wrote: >>>>>>>> >>>>>>>> The Smart Voltage Scaling(SVS) engine is a piece of hardware >>>>>>>> which calculates suitable SVS bank voltages to OPP voltage table. >>>>>>>> Then, DVFS driver could apply those SVS bank voltages to PMIC/Buck >>>>>>>> when receiving OPP_EVENT_ADJUST_VOLTAGE. >>>>>>>> >>>>>>>> 1. SVS driver uses OPP adjust event in [1] to update OPP table voltage part. >>>>>>>> 2. SVS driver gets thermal/GPU device by node [2][3] and CPU device by get_cpu_device(). >>>>>>>> After retrieving subsys device, SVS driver calls device_link_add() to make sure probe/suspend callback priority. >>>>>>>> >>>>>>>> [1] https://git.kernel.org/pub/scm/linux/kernel/git/vireshk/pm.git/commit/?h=opp/linux-next&id=25cb20a212a1f989385dfe23230817e69c62bee5 >>>>>>>> [2] https://git.kernel.org/pub/scm/linux/kernel/git/vireshk/pm.git/commit/?h=opp/linux-next&id=b325ce39785b1408040d90365a6ab1aa36e94f87 >>>>>>>> [3] https://git.kernel.org/pub/scm/linux/kernel/git/matthias.bgg/linux.git/commit/?h=v5.16-next/dts64&id=a8168cebf1bca1b5269e8a7eb2626fb76814d6e2 >>>>>>>> >>>>>>>> Change since v24: >>>>>>>> - Rebase to Linux 5.18-rc6 >>>>>>>> - Show specific fail log in svs_platform_probe() to help catch which step fails quickly >>>>>>>> - Remove struct svs_bank member "pd_dev" because all subsys device's power domain has been merged into one node like above [3] >>>>>>>> >>>>>>>> Test in below environment: >>>>>>>> SW: Integration Tree [4] + Thermal patch [5] + SVS v25 (this patchset) >>>>>>>> HW: mt8183-Krane >>>>>>>> >>>>>>>> [4] https://protect2.fireeye.com/v1/url?k=847bae75-e5f0bb43-847a253a-000babff9b5d-0b6f42041b9dea1d&q=1&e=37a26c43-8564-4808-9701-dc76d1ebbb27&u=https%3A%2F%2Fgithub.com%2Fwens%2Flinux%2Fcommits%2Fmt8183-cpufreq-cci-svs-test >>>>>>> >>>>>>> I've updated my branch to include all the latest versions of the relevant >>>>>>> patch series: >>>>>>> >>>>>>> - anx7625 DPI bus type series v2 (so the display works) >>>>>>> - MT8183 thermal series v9 (this seems to have been overlooked by the >>>>>>> maintainer) >>>>>>> - MTK SVS driver series v25 >>>>>>> - devfreq: cpu based scaling support to passive governor series v5 >>>>>>> - MTK CCI devfreq series v4 >>>>>>> - MT8183 cpufreq series v7 >>>>>>> - Additional WIP patches for panfrost MTK devfreq >>>>>> >>>>>> Thanks for preparing an integration branch Chen-Yu. >>>>>> >>>>>> I'm testing this on mt8183-pumpkin with one patch to add the CCI >>>>>> regulator[1], and the defconfig you posted in a previous rev of this >>>>>> series, but the CCI driver still causes a fault on boot[2] on my >>>>>> platform. >>>>>> >>>>>> I mentioned in earlier reviews that I think there's potentially a race >>>>>> between CCI and SVS loading since they are co-dependent. My hunch is >>>>>> that this is still not being handled properly. >>>>> >>>>> Ah, actually it's crashing when I try to boot the platform with >>>>> `maxcpus=4` on the cmdline (which I have to do because mt8183-pumpkin is >>>>> unstable upstream with the 2nd cluster enabled.) >> >> This warning message is printed by 'WARN_ON(cpufreq_passive_unregister_notifier(devfreq))' >> on devfreq passive governor. >> >> If the cpufreq drivers are not probed before of probing cci devfreq driver >> with passive governor, passive governor shows this warning message. >> Because passive governor with CPUFREQ_PARENT_DEV depends on the cpufreq driver >> in order to get 'struct cpufreq_policy'[2]. >> >> [1] https://git.kernel.org/pub/scm/linux/kernel/git/chanwoo/linux.git/tree/drivers/devfreq/governor_passive.c?h=devfreq-testing#n339 >> [2] https://git.kernel.org/pub/scm/linux/kernel/git/chanwoo/linux.git/tree/drivers/devfreq/governor_passive.c?h=devfreq-testing#n282 >> >> But, as I knew, this message might not stop the kernel. Just show the warning >> message and then return -EPROBE_DEFER error. It means that maybe try to >> probe the cci devfreq driver on late time of kernel booting >> and then will be working. But, I need the full kernel booting log >> and the booting sequence of between cpufreq and cci devfreq driver. > > Maybe just use a standard dev_warn() instead? WARN_ON causes all sorts > of panicking in developers' minds. :p OK. I'll use dev_warn() instead of WARN_ON. > >> In order to fix your issue, could you share the full booting log? >> And if possible, please explain the more detailed something about this. > > The shortened version is that on an 8 core system, with maxcpus=4, > only the first four cores are booted and have cpufreq associated. > I've not actually used this mechanism, so I don't really know what > happens if the other cores are brought up later with hotplug. Is > cpufreq expected to attach to them? > > Maybe Kevin can add some more details. > > > ChenYu > > >>>>> >>>>> The CCI driver should be a bit more robust about detecting >>>>> available/online CPUs >>>> >>>> This all seems to be handled in the devfreq passive governor. >>> >>> Well, that's the initial crash. But the SVS driver will also go through >>> its svs_mt8183_banks[] array (including both big & little clusters) and >>> try to init SVS, so presumably that will have some problems also if only >>> one cluster is enabled. >>> >>>> And presumably we'd like to have CCI devfreq running even if just one >>>> core was booted. >>> >>> Yes, I assume so also. >>> >>>> Added Chanwoo for more ideas. >>> >>> OK, thanks. >>> >>> Kevin >> >> >> -- >> Best Regards, >> Chanwoo Choi >> Samsung Electronics > > -- Best Regards, Chanwoo Choi Samsung Electronics
