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From: "Rafael J. Wysocki" <rafael@kernel.org>
Date: Thu, 21 Sep 2017 02:24:59 +0200
Message-ID: <CAJZ5v0jJ-WQ15BNHrno_DFqyJU1Rn4KaBnaA5bbK8WmmmWfNgw@mail.gmail.com>
Subject: Re: [PATCH 1/2] i2c: designware: switch to suspend_late/resume_early
To: Rajat Jain <rajatja@google.com>
Cc: Jarkko Nikula <jarkko.nikula@linux.intel.com>,
        Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        Mika Westerberg <mika.westerberg@linux.intel.com>,
        Wolfram Sang <wsa@the-dreams.de>,
        linux-i2c <linux-i2c@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Lee Jones <lee.jones@linaro.org>,
        "Wysocki, Rafael J" <rafael.j.wysocki@intel.com>,
        "Rafael J. Wysocki" <rjw@rjwysocki.net>,
        Linux PM <linux-pm@vger.kernel.org>, Len Brown <len.brown@intel.com>,
        furquan@google.com, rajatxjain@gmail.com
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On Thu, Sep 21, 2017 at 12:31 AM, Rajat Jain <rajatja@google.com> wrote:
> Ref: https://lkml.org/lkml/2017/9/19/649
>
> The bus controllers should suspend the bus operations only after
> all of the devices on the bus have suspended their device
> completely. Since the i2c_client drivers could be talking to
> their devices in their suspend_late() calls, lets ensure that the
> bus is alive by that time. Thus moving the controller suspend logic to
> suspend_late().
>
> Signed-off-by: Rajat Jain <rajatja@google.com>
> ---
>  drivers/i2c/busses/i2c-designware-platdrv.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c
> index 0e65b97842b4..66dd7f844c40 100644
> --- a/drivers/i2c/busses/i2c-designware-platdrv.c
> +++ b/drivers/i2c/busses/i2c-designware-platdrv.c
> @@ -468,7 +468,7 @@ static int dw_i2c_plat_suspend(struct device *dev)
>  static const struct dev_pm_ops dw_i2c_dev_pm_ops = {
>         .prepare = dw_i2c_plat_prepare,
>         .complete = dw_i2c_plat_complete,
> -       SET_SYSTEM_SLEEP_PM_OPS(dw_i2c_plat_suspend, dw_i2c_plat_resume)
> +       SET_LATE_SYSTEM_SLEEP_PM_OPS(dw_i2c_plat_suspend, dw_i2c_plat_resume)
>         SET_RUNTIME_PM_OPS(dw_i2c_plat_runtime_suspend,
>                            dw_i2c_plat_resume,
>                            NULL)

No, you can't just do that.

I sent patches to do it properly before my trip to LA last week, it
shouldn't be overly difficult to find them in the mailing list
archives.  I can look them up tomorrow if need be.

Thanks,
Rafael