netdev - Re: [PATCH] net: wwan: t7xx: Ensure init is completed before system sleep

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Date: Wed, 17 May 2023 12:28:16 +0800
From: Kai-Heng Feng <kai.heng.feng@...onical.com>
To: Piotr Raczynski <piotr.raczynski@...el.com>
Cc: chandrashekar.devegowda@...el.com, linuxwwan@...el.com, 
	chiranjeevi.rapolu@...ux.intel.com, haijun.liu@...iatek.com, 
	m.chetan.kumar@...ux.intel.com, ricardo.martinez@...ux.intel.com, 
	Loic Poulain <loic.poulain@...aro.org>, Sergey Ryazanov <ryazanov.s.a@...il.com>, 
	Johannes Berg <johannes@...solutions.net>, "David S. Miller" <davem@...emloft.net>, 
	Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, 
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] net: wwan: t7xx: Ensure init is completed before system sleep

On Tue, May 16, 2023 at 6:42 PM Piotr Raczynski
<piotr.raczynski@...el.com> wrote:
>
> On Tue, May 16, 2023 at 04:03:27PM +0800, Kai-Heng Feng wrote:
> > When the system attempts to sleep while mtk_t7xx is not ready, the driver
> > cannot put the device to sleep:
> > [   12.472918] mtk_t7xx 0000:57:00.0: [PM] Exiting suspend, modem in invalid state
> > [   12.472936] mtk_t7xx 0000:57:00.0: PM: pci_pm_suspend(): t7xx_pci_pm_suspend+0x0/0x20 [mtk_t7xx] returns -14
> > [   12.473678] mtk_t7xx 0000:57:00.0: PM: dpm_run_callback(): pci_pm_suspend+0x0/0x1b0 returns -14
> > [   12.473711] mtk_t7xx 0000:57:00.0: PM: failed to suspend async: error -14
> > [   12.764776] PM: Some devices failed to suspend, or early wake event detected
> >
> > Mediatek confirmed the device can take a rather long time to complete
> > its initialization, so wait for up to 20 seconds until init is done.
> >
> > Signed-off-by: Kai-Heng Feng <kai.heng.feng@...onical.com>
>
> Does it fix any issue? Anyway target tree would help here I guess.

It fixes "PM: failed to suspend async: error -14" mentioned in the
commit message.

>
> [...]
>
> > +static int t7xx_pci_pm_prepare(struct device *dev)
> > +{
> > +     struct pci_dev *pdev = to_pci_dev(dev);
> > +     struct t7xx_pci_dev *t7xx_dev;
> > +
> > +     t7xx_dev = pci_get_drvdata(pdev);
> > +     if (!wait_for_completion_timeout(&t7xx_dev->init_done, 20 * HZ))
>
> #define T7XX_INIT_TIMEOUT or something similar wouldn't do any harm here.

Sure, will do in next revision.

>
> > +             dev_warn(dev, "Not ready for system sleep.\n");
> > +
> > +     return 0;
>
> So in case of a timeout you still return 0, is that OK?

You are right, error code should be returned instead.

Kai-Heng

>
> [...]
> Thanks, Piotr.