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From: Sakari Ailus <sakari.ailus@linux.intel.com>
To: Randy Dunlap <rdunlap@infradead.org>
Cc: linux-i2c@vger.kernel.org, Wolfram Sang <wsa@the-dreams.de>,
	"Rafael J. Wysocki" <rafael@kernel.org>,
	linux-acpi@vger.kernel.org, Bingbu Cao <bingbu.cao@intel.com>,
	linux-media@vger.kernel.org,
	Chiranjeevi Rapolu <chiranjeevi.rapolu@intel.com>,
	Hyungwoo Yang <hyungwoo.yang@intel.com>,
	Bartosz Golaszewski <bgolaszewski@baylibre.com>,
	Arnd Bergmann <arnd@arndb.de>,
	linux-kernel@vger.kernel.org,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	rajmohan.mani@intel.com, Tomasz Figa <tfiga@chromium.org>,
	"Qiu, Tian Shu" <tian.shu.qiu@intel.com>
Subject: Re: [PATCH v6 6/6] Documentation: ACPI: Document allow-low-power-probe _DSD property
Date: Thu, 27 Aug 2020 16:28:22 +0300
Message-ID: <20200827132822.GI24582@paasikivi.fi.intel.com> (raw)
In-Reply-To: <ac5a7cb9-7fd1-fb73-b872-d5a58846d99f@infradead.org>

On Wed, Aug 26, 2020 at 11:06:22AM -0700, Randy Dunlap wrote:
> On 8/26/20 4:54 AM, Sakari Ailus wrote:
> > Document the probe-low-power _DSD property and how it is used with I²C
> > drivers.
> > 
> > Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
> > ---
> >  .../acpi/dsd/allow-low-power-probe.rst        | 28 +++++++++++++++++++
> >  Documentation/firmware-guide/acpi/index.rst   |  1 +
> >  2 files changed, 29 insertions(+)
> >  create mode 100644 Documentation/firmware-guide/acpi/dsd/allow-low-power-probe.rst
> > 
> > diff --git a/Documentation/firmware-guide/acpi/dsd/allow-low-power-probe.rst b/Documentation/firmware-guide/acpi/dsd/allow-low-power-probe.rst
> > new file mode 100644
> > index 0000000000000..6fcc89162b898
> > --- /dev/null
> > +++ b/Documentation/firmware-guide/acpi/dsd/allow-low-power-probe.rst
> > @@ -0,0 +1,28 @@
> > +.. SPDX-License-Identifier: GPL-2.0
> > +
> > +======================================
> > +Probing I²C devices in low power state
> > +======================================
> > +
> > +Introduction
> > +============
> > +
> > +In some cases it may be preferred to leave certain devices powered off for the
> > +entire system bootup if powering on these devices has adverse side effects,
> > +beyond just powering on the said device. Linux recognizes the _DSD property
> > +"allow-low-power-probe" that can be used for this purpose.
> > +
> > +How it works
> > +============
> > +
> > +The property "allow-low-power-probe" boolean property may be used to tell Linux
> 
> Drop the first "property".
> 

Thanks, will fix for v7.

> > +that the I²C framework should instruct the kernel ACPI framework to leave the
> > +device in the low power state. If the driver indicates its support for this by
> > +setting the I2C_DRV_FL_ALLOW_LOW_POWER_PROBE flag in struct i2c_driver.flags

This is leftover from v5 actually, I'll change the documentation to mention
the allow_low_power_probe as well.

> > +field and the "allow-low-power-probe" property is present, the device will not
> > +be powered on for probe.
> 

-- 
Kind regards,

Sakari Ailus

  reply index

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-26 11:54 [PATCH v6 0/6] Support running driver's probe for a device powered off Sakari Ailus
2020-08-26 11:54 ` [PATCH v6 1/6] i2c: Allow an ACPI driver to manage the device's power state during probe Sakari Ailus
2020-08-28  8:38   ` Wolfram Sang
2020-08-31  8:23     ` Sakari Ailus
2020-08-31  9:31       ` Wolfram Sang
2020-08-31  9:54         ` Sakari Ailus
2020-08-31 10:00   ` Wolfram Sang
2020-08-31 17:05     ` Sakari Ailus
2020-08-26 11:54 ` [PATCH v6 2/6] ACPI: Add a convenience function to tell a device is in low power state Sakari Ailus
2020-08-26 11:54 ` [PATCH v6 3/6] ov5670: Support probe whilst the device is in a " Sakari Ailus
2020-08-26 11:54 ` [PATCH v6 4/6] media: i2c: imx319: Support probe while the device is off Sakari Ailus
2020-08-26 11:54 ` [PATCH v6 5/6] at24: Support probing while off Sakari Ailus
2020-08-26 11:54 ` [PATCH v6 6/6] Documentation: ACPI: Document allow-low-power-probe _DSD property Sakari Ailus
2020-08-26 18:06   ` Randy Dunlap
2020-08-27 13:28     ` Sakari Ailus [this message]
2020-09-01 20:28       ` Sakari Ailus

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