Hi Stanisław, On Wed, Aug 30, 2023 at 3:32 PM Stanisław Kardach <skardach@xxxxxxxxxx> wrote: > > On Wed, Aug 30, 2023 at 4:27 AM Ben Chuang <benchuanggli@xxxxxxxxx> wrote: > > > > Hi, > > On Wed, Aug 30, 2023 at 12:35 AM Sven van Ashbrook <svenva@xxxxxxxxxxxx> wrote: > > > > > > + Rafael for advice on runtime_pm corner cases. > > > > > > On Mon, Aug 28, 2023 at 10:48 PM Ben Chuang <benchuanggli@xxxxxxxxx> wrote: > > > > > > > > > > > > My concern is that when runtime_pm is false, gl9763e is disabled LPM > > > > negotiation, gl9763e can't enter L1.x and s0ix may fail. > > > > It seems that runtime_pm will always exist and that's ok. > > > > > > > > > > Thank you. I believe we can address your concern. > > > > > > - XXX_suspend/XXX_resume (i.e. classic suspend/resume) depends on > > > CONFIG_PM_SLEEP. This always selects CONFIG_PM. This always includes > > > the runtime_pm framework. So, if XXX_suspend/XXX_resume gets called, > > > the runtime_pm framework is always present, but may not be actively > > > managing the device. > > This is ok. > > > > > > > > - "when runtime_pm is false" AFAIK the only way to disable runtime_pm > > > when CONFIG_PM is set, is to write "on" to /sys/devices/.../power/control. > > > See https://www.kernel.org/doc/Documentation/ABI/testing/sysfs-devices-power > > > In that case, the runtime_pm framework will activate the device, calling > > > XXX_runtime_resume() if necessary. Are there other ways of disabling it? > > > > > > - if /sys/devices/.../power/control is "on", then: > > > gl9763e_runtime_resume() always called -> LPM always disabled > > > gl9763e_suspend() -> LPM enabled -> gl9763e_resume() -> LPM disabled > > > In between "classic" XXX_suspend and XXX_resume, LPM will be enabled, > > > so the device can enter L1.x and S0ix. > > In this cas, after gl9763e_resume(), it is LPM disabled. > > Is there no chance for gl9763e to enter L1.x again when the system is idle? > With runtime PM disabled via sysfs, the short answer is not since > https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=f9e5b33934cec24b8c024add5c5d65d2f93ade05. > > The longer answer is: > 1. System boots up with LPM flags in PCI config space in default value > (might be LPM enabled). > 2.1. If runtime PM is disabled before first runtime suspend - > registers will be left in their default state. > 2.2. If runtime PM is disabled after first runtime suspend, the device > will be woken up and the gl9763e runtime resume callback will disable > LPM. OK. Thank you for your answer. Best Regards, Ben Chuang > > > > > > > > And the LPM negotiation flags look correct. > > > Does that address your concerns? > > > > Best regards, > > Ben Chuang > > -- > Best Regards, > Stanisław Kardach
