linux-kernel - Re: [PATCH v9 0/4] Allow USB devices to remain runtime-suspended when sleeping

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Message-ID: <8710988.MO9zH1zeoz@vostro.rjw.lan>
Date:	Mon, 05 Oct 2015 22:26:48 +0200
From:	"Rafael J. Wysocki" <rjw@...ysocki.net>
To:	Tomeu Vizoso <tomeu.vizoso@...labora.com>
Cc:	linux-pm@...r.kernel.org, Alan Stern <stern@...land.harvard.edu>,
	martyn.welch@...labora.co.uk, Ulf Hansson <ulf.hansson@...aro.org>,
	David Airlie <airlied@...ux.ie>,
	Tomas Winkler <tomas.winkler@...el.com>,
	linux-usb@...r.kernel.org, linux-acpi@...r.kernel.org,
	linux-kernel@...r.kernel.org, dri-devel@...ts.freedesktop.org,
	Russell King <linux@....linux.org.uk>,
	Len Brown <lenb@...nel.org>, Len Brown <len.brown@...el.com>,
	Kevin Hilman <khilman@...nel.org>,
	Tony Lindgren <tony@...mide.com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	linux-omap@...r.kernel.org, Pavel Machek <pavel@....cz>,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v9 0/4] Allow USB devices to remain runtime-suspended when sleeping

On Monday, October 05, 2015 04:45:28 PM Tomeu Vizoso wrote:
> Hi,
> 
> this is v9 of an attempt to make it easier for devices to remain in
> runtime PM when the system goes to sleep, mainly to reduce the time
> spent resuming devices.
> 
> For this, we interpret the absence of all PM callback implementations as
> it being safe to do direct_complete, so their ancestors aren't prevented
> from remaining runtime-suspended.
> 
> Additionally, the prepare() callback of USB devices will return 1 if
> runtime PM is enabled and the current wakeup settings are correct.
> 
> With these changes, a uvcvideo device (for example) stays in runtime
> suspend when the system goes to sleep and is left in that state when the
> system resumes, not delaying it unnecessarily.
> 
> Thanks,
> 
> Tomeu
> 
> Changes in v9:
> - Add docs noting the need for the device lock to be held before calling
>   device_is_bound()
> - Add docs noting the need for the device lock to be held before calling
>   dev_pm_domain_set()
> - Move to CONFIG_PM_SLEEP as suggested by Rafael and Ulf.
> - Rename from device_check_pm_callbacks to device_pm_check_callbacks to
>   follow with the naming convention of existing API.
> - Re-add calling to device_pm_check_callbacks from device registration
>   and when updating the PM domain of a device.
> 
> Changes in v8:
> - Add device_is_bound()
> - Add dev_pm_domain_set() and update code to use it
> - Move no_pm_callbacks field into CONFIG_PM_SLEEP
> - Call device_check_pm_callbacks only after a device is bound or unbound
> 
> Changes in v7:
> - Reduce indentation by adding a label in device_prepare()
> 
> Changes in v6:
> - Add stub for !CONFIG_PM.
> - Move implementation of device_check_pm_callbacks to power/main.c as it
>   doesn't belong to CONFIG_PM_SLEEP.
> - Take dev->power.lock before modifying flag.
> 
> Changes in v5:
> - Check for all dev_pm_ops instances associated to a device, updating a
>   no_pm_callbacks flag at the times when that could change.
> 
> Tomeu Vizoso (4):
>   device core: add device_is_bound()
>   PM / Domains: add setter for dev.pm_domain
>   PM / sleep: Go direct_complete if driver has no callbacks
>   USB / PM: Allow USB devices to remain runtime-suspended when sleeping
> 
>  arch/arm/mach-omap2/omap_device.c |  7 ++++---
>  drivers/acpi/acpi_lpss.c          |  5 +++--
>  drivers/acpi/device_pm.c          |  5 +++--
>  drivers/base/dd.c                 | 21 +++++++++++++++++++--
>  drivers/base/power/clock_ops.c    |  5 +++--
>  drivers/base/power/common.c       | 24 ++++++++++++++++++++++++
>  drivers/base/power/domain.c       |  6 ++++--
>  drivers/base/power/main.c         | 35 +++++++++++++++++++++++++++++++++++
>  drivers/base/power/power.h        |  3 +++
>  drivers/gpu/vga/vga_switcheroo.c  | 10 +++++-----
>  drivers/misc/mei/pci-me.c         |  5 +++--
>  drivers/misc/mei/pci-txe.c        |  5 +++--
>  drivers/usb/core/port.c           |  6 ++++++
>  drivers/usb/core/usb.c            | 11 ++++++++++-
>  include/linux/device.h            |  2 ++
>  include/linux/pm.h                |  1 +
>  include/linux/pm_domain.h         |  3 +++
>  17 files changed, 131 insertions(+), 23 deletions(-)

The series looks good to me now, but patch [4/4] needs an ACK from the USB
maintainers and patch [1/4] needs an ACK from Greg.

Thanks,
Rafael

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