linux-kernel - Re: [PATCH 1/2] host: ehci-exynos: Convert to use the SET_SYSTEM_SLEEP_PM

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Message-ID: <20161009183933.GA15270@kozik-lap>
Date:   Sun, 9 Oct 2016 21:39:33 +0300
From:   Krzysztof Kozlowski <krzk@...nel.org>
To:     Anand Moon <linux.amoon@...il.com>
Cc:     Krzysztof Kozlowski <krzk@...nel.org>,
        Alan Stern <stern@...land.harvard.edu>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Kukjin Kim <kgene@...nel.org>,
        Javier Martinez Canillas <javier@....samsung.com>,
        Linux USB Mailing List <linux-usb@...r.kernel.org>,
        linux-arm-kernel <linux-arm-kernel@...ts.infradead.org>,
        "linux-samsung-soc@...r.kernel.org" 
        <linux-samsung-soc@...r.kernel.org>,
        Linux Kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/2] host: ehci-exynos: Convert to use the
 SET_SYSTEM_SLEEP_PM_OPS

On Sun, Oct 09, 2016 at 11:57:59PM +0530, Anand Moon wrote:
> hi Krzysztof,
> 
> On 9 October 2016 at 22:57, Krzysztof Kozlowski <krzk@...nel.org> wrote:
> > On Sun, Oct 09, 2016 at 10:45:40PM +0530, Anand Moon wrote:
> >> Hi Krzysztof,
> >>
> >> On 9 October 2016 at 22:04, Krzysztof Kozlowski <krzk@...nel.org> wrote:
> >> > On Sun, Oct 09, 2016 at 02:34:14PM +0000, Anand Moon wrote:
> >> >> Move the ehci-exynos system PM callbacks within #ifdef CONFIG_PM_SLEEP
> >> >> as to avoid them being build when not used. This also allows us to use the
> >> >> SET_SYSTEM_SLEEP_PM_OPS macro which simplifies the code.
> >> >>
> >> >> Signed-off-by: Anand Moon <linux.amoon@...il.com>
> >> >> ---
> >> >>  drivers/usb/host/ehci-exynos.c | 14 ++++++--------
> >> >>  1 file changed, 6 insertions(+), 8 deletions(-)
> >> >>
> >> >> diff --git a/drivers/usb/host/ehci-exynos.c b/drivers/usb/host/ehci-exynos.c
> >> >> index 42e5b66..1899900 100644
> >> >> --- a/drivers/usb/host/ehci-exynos.c
> >> >> +++ b/drivers/usb/host/ehci-exynos.c
> >> >> @@ -251,7 +251,7 @@ static int exynos_ehci_remove(struct platform_device *pdev)
> >> >>       return 0;
> >> >>  }
> >> >>
> >> >> -#ifdef CONFIG_PM
> >> >> +#ifdef CONFIG_PM_SLEEP
> >> >
> >> > Does not look like an equivalent change. How will it behave in a config
> >> > with !SUSPEND && !HIBERNATE && PM?
> >> >
> >>
> >> [snip]
> >>
> >> I just wanted to update suspend and resume callback to use
> >> SET_SYSTEM_SLEEP_PM_OPS
> >> as they are define under CONFIG_PM_SLEEP so I update above to avoid
> >> compilation warning/error.
> >
> Apologize: for not understanding your question.
> 
> > First of all you did not answer to my question, so let me rephrase into
> > two:
> > 1. Is the code equivalent?
> 
> No CONFIG_PM and CONFIG_PM_SLEEP are different options.
> But I could not disable CONFIG_PM_SLEEP option with either in exynos_defconfig

So the code is not equivalent...

> 
> CONFIG_PM_SLEEP=n or
> # CONFIG_PM_SLEEP is not set
> 
> > 2. What will be the output with !SUSPEND && !HIBERNATE && PM?
> 
> #
> # Power management options
> #
> # CONFIG_SUSPEND is not set
> # CONFIG_HIBERNATION is not set
> # CONFIG_PM is not set
> 
> When CONFIG_SUSPEND and CONFIG_HIBERNATION are not set
> CONFIG_PM is disabled and so is CONFIG_PM_SLEEP.

In my config, the CONFIG_PM was enabled thus the code changes the
functionality... Maybe this was intented but I really don't get it from
the commit message or from your explanations here.

Krzysztof