Re: [PATCH 2/8] ACPI: PM: Use the new device_to_pm() helper to access struct dev_pm_ops

From: Pavel Machek <pavel@denx.de>
To: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: "Krzysztof Wilczyński" <kw@linux.com>,
	"Dan Carpenter" <dan.carpenter@oracle.com>,
	"Rafael J. Wysocki" <rjw@rjwysocki.net>,
	"Len Brown" <lenb@kernel.org>,
	"Kevin Hilman" <khilman@kernel.org>,
	"Ulf Hansson" <ulf.hansson@linaro.org>,
	"Greg Kroah-Hartman" <gregkh@linuxfoundation.org>,
	"Johan Hovold" <johan@kernel.org>,
	"Alex Elder" <elder@kernel.org>,
	"Bjorn Helgaas" <bhelgaas@google.com>,
	"James E.J. Bottomley" <jejb@linux.ibm.com>,
	"Martin K. Petersen" <martin.petersen@oracle.com>,
	"Felipe Balbi" <balbi@kernel.org>,
	"Julian Wiedmann" <jwi@linux.ibm.com>,
	"Karsten Graul" <kgraul@linux.ibm.com>,
	"Ursula Braun" <ubraun@linux.ibm.com>,
	"Jakub Kicinski" <kuba@kernel.org>,
	"Bjorn Andersson" <bjorn.andersson@linaro.org>,
	"John Stultz" <john.stultz@linaro.org>,
	"David S. Miller" <davem@davemloft.net>,
	greybus-dev@lists.linaro.org, netdev <netdev@vger.kernel.org>,
	"ACPI Devel Maling List" <linux-acpi@vger.kernel.org>,
	"Linux PCI" <linux-pci@vger.kernel.org>,
	"Linux PM" <linux-pm@vger.kernel.org>,
	linux-s390@vger.kernel.org,
	"open list:TARGET SUBSYSTEM" <linux-scsi@vger.kernel.org>,
	"open list:ULTRA-WIDEBAND (UWB) SUBSYSTEM:"
	<linux-usb@vger.kernel.org>
Subject: Re: [PATCH 2/8] ACPI: PM: Use the new device_to_pm() helper to access struct dev_pm_ops
Date: Tue, 26 May 2020 11:45:18 +0200	[thread overview]
Message-ID: <20200526094518.GA4600@amd> (raw)
In-Reply-To: <CAJZ5v0jQUmdDYmJsP43Ja3urpVLUxe-yD_Hm_Jd2LtCoPiXsrQ@mail.gmail.com>

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On Tue 2020-05-26 10:37:36, Rafael J. Wysocki wrote:
> On Mon, May 25, 2020 at 8:26 PM Krzysztof Wilczyński <kw@linux.com> wrote:
> >
> > Use the new device_to_pm() helper to access Power Management callbacs
> > (struct dev_pm_ops) for a particular device (struct device_driver).
> >
> > No functional change intended.
> >
> > Signed-off-by: Krzysztof Wilczyński <kw@linux.com>
> > ---
> >  drivers/acpi/device_pm.c | 5 +++--
> >  1 file changed, 3 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/acpi/device_pm.c b/drivers/acpi/device_pm.c
> > index 5832bc10aca8..b98a32c48fbe 100644
> > --- a/drivers/acpi/device_pm.c
> > +++ b/drivers/acpi/device_pm.c
> > @@ -1022,9 +1022,10 @@ static bool acpi_dev_needs_resume(struct device *dev, struct acpi_device *adev)
> >  int acpi_subsys_prepare(struct device *dev)
> >  {
> >         struct acpi_device *adev = ACPI_COMPANION(dev);
> > +       const struct dev_pm_ops *pm = driver_to_pm(dev->driver);
> 
> I don't really see a reason for this change.
> 
> What's wrong with the check below?

Duplicated code. Yes, compiler can sort it out, but... new version
looks better to me.

Best regards,
								pavel

> >
> > -       if (dev->driver && dev->driver->pm && dev->driver->pm->prepare) {
> > -               int ret = dev->driver->pm->prepare(dev);
> > +       if (pm && pm->prepare) {
> > +               int ret = pm->prepare(dev);

-- 
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