linux-kernel - Re: [PATCH 1/3] i2c: designware: Enable async suspend / resume of designware devices

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Message-ID: <CAE_wzQ8nBBHMr4c=SXVpDq2iz=eu0RbJgTHrKkU1_Hsdj9SLzQ@mail.gmail.com>
Date:   Fri, 22 Oct 2021 09:53:40 -0700
From:   Dmitry Torokhov <dtor@...gle.com>
To:     Jarkko Nikula <jarkko.nikula@...ux.intel.com>
Cc:     Rajat Jain <rajatja@...gle.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        Wolfram Sang <wsa@...nel.org>, linux-i2c@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-pm@...r.kernel.org,
        rajatxjain@...il.com, dbasehore@...omium.org
Subject: Re: [PATCH 1/3] i2c: designware: Enable async suspend / resume of
 designware devices

Hi Jarkko,

On Fri, Oct 22, 2021 at 4:37 AM Jarkko Nikula
<jarkko.nikula@...ux.intel.com> wrote:
>
> On 10/22/21 5:28 AM, Rajat Jain wrote:
> > Mark the designware devices for asynchronous suspend. With this, the
> > resume for designware devices does not get stuck behind other unrelated
> > devices (e.g. intel_backlight that takes hundreds of ms to resume,
> > waiting for its parent devices).
> >
> > Signed-off-by: Rajat Jain <rajatja@...gle.com>
> > ---
> >   drivers/i2c/busses/i2c-designware-platdrv.c | 2 ++
> >   1 file changed, 2 insertions(+)
> >
> > diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c
> > index 21113665ddea..2bd81abc86f6 100644
> > --- a/drivers/i2c/busses/i2c-designware-platdrv.c
> > +++ b/drivers/i2c/busses/i2c-designware-platdrv.c
> > @@ -293,6 +293,8 @@ static int dw_i2c_plat_probe(struct platform_device *pdev)
> >                                       DPM_FLAG_MAY_SKIP_RESUME);
> >       }
> >
> > +     device_enable_async_suspend(&pdev->dev);
> > +
> >       /* The code below assumes runtime PM to be disabled. */
> >       WARN_ON(pm_runtime_enabled(&pdev->dev));
> >
> I guess same can be done to i2c_dw_pci_probe() too. I don't have any
> strong opinion should it be done in this patch or somewhere in the future.

All PCI devices are marked for asynchronous suspend/resume by default.
See drivers/pci/pci.c::pci_pm_init().

Thanks,
Dmitry