linux-kernel - RE: [PATCH] PM / runtime: Drop children check from __pm_runtime_set

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Date:   Wed, 29 Nov 2017 08:21:32 +0000
From:   Yoshihiro Shimoda <yoshihiro.shimoda.uh@...esas.com>
To:     Ulf Hansson <ulf.hansson@...aro.org>
CC:     Geert Uytterhoeven <geert@...ux-m68k.org>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Linux PM <linux-pm@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Alan Stern <stern@...land.harvard.edu>,
        "USB list" <linux-usb@...r.kernel.org>,
        Linux-Renesas <linux-renesas-soc@...r.kernel.org>
Subject: RE: [PATCH] PM / runtime: Drop children check from
 __pm_runtime_set_status()

Hi,

> From: Ulf Hansson, Sent: Wednesday, November 29, 2017 2:23 AM
> 
> On 28 November 2017 at 13:48, Yoshihiro Shimoda
> <yoshihiro.shimoda.uh@...esas.com> wrote:
> > Hi Geert-san,
> >
> >> From: Geert Uytterhoeven, Sent: Tuesday, November 28, 2017 7:58 PM
> >>
> >> Hi Rafael, Shimoda-san,
> >>
> >> On Sun, Nov 12, 2017 at 1:27 AM, Rafael J. Wysocki <rjw@...ysocki.net> wrote:
> >> > From: Rafael J. Wysocki <rafael.j.wysocki@...el.com>
<snip>
> >> JFTR, this triggered before during system resume on e.g. Salvator-XS with
> >> R-Car H3:
> >>
> >>     ohci-platform ee080000.usb: runtime PM trying to suspend device
> >> but active child
> >>     phy_rcar_gen3_usb2 ee080200.usb-phy: runtime PM trying to suspend
> >> device but active child
> >>     ohci-platform ee0c0000.usb: runtime PM trying to suspend device
> >> but active child
> >>     ohci-platform ee0a0000.usb: runtime PM trying to suspend device
> >> but active child
> >>     phy_rcar_gen3_usb2 ee0c0200.usb-phy: runtime PM trying to suspend
> >> device but active child
> >>     phy_rcar_gen3_usb2 ee0a0200.usb-phy: runtime PM trying to suspend
> >> device but active child
> >>
> >> so this was an existing issue with USB before.
> >
> > Thank you for the report!
> > I know that, but since this didn't cause any trouble until now,
> > I postponed to investigate the issue... But, I investigate it today.
> > I don't find the root cause yet. However, it seems related to usb host and/or usb core.
> > --> USB host related devices' child_count will be 1 in suspend timing.
> >  --> I guess remote wakeup feature is enabled? But, I don't find the point yet.
> 
> I am guessing the issue is triggered by genpd in the suspend noirq
> phase (genpd_suspend_noirq()). In there,  there is a call to
> pm_runtime_force_suspend() (which calls pm_runtime_set_suspended() and
> which triggered the earlier error messages being printed).
> 
> The reason why genpd calls pm_runtime_force_suspend(), is because when
> validating wakeup configurations for the device "if
> (dev->power.wakeup_path && genpd_is_active_wakeup(genpd))", it's
> thinks wakeup isn't configured while it probably should be.
> 
> An additional note, only when genpd has the GENPD_FLAG_PM_CLK set,
> which makes the genpd->dev_ops.stop|start() being assigned, genpd
> calls pm_runtime_force_suspend() - else it doesn't.
> 
> Perhaps try out the series I recently posted improving the code
> dealing with wakeups in genpd and the PM core:
> https://www.spinics.net/lists/linux-renesas-soc/msg20122.html
> To that, you need to set the new flag (invented in the above series)
> DPM_FLAG_IN_BAND_WAKEUP in the driver that configures wakeup of its
> device.
> 
> Hope this helps!

Thank you for the comments!
I tried DPM_FLAG_IN_BAND_WAKEUP, but the issue still exists.
I added the flag in the [eo]hci-platform driver and usb/core/driver.c.
I also added the flag in the phy_rcar_gen3_usb2 driver except usb host drivers.

> > The renesas_usbhs also uses the phy_rcar_gen3_usb2 driver.
> > --> If I only used the renesas_usbhs driver (in other words, I don't install
> >     [eo]hci-{hcd,platform} drivers), the issue disappeared.
> >  --> So, I think the phy_rcar_gen3_usb2 driver doesn't cause this issue.
> >     (But, it is possible to be related though.)
> >
> > I'll continue to investigate this issue tomorrow.
> 
> Please keep me posted, I am interested about the why the problem exists. :-)

Sure! :)

Best regards,
Yoshihiro Shimoda

> Kind regards
> Uffe