From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
To: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Mika Westerberg <mika.westerberg@linux.intel.com>,
Bjorn Helgaas <bhelgaas@google.com>,
Jean Delvare <khali@linux-fr.org>,
ben-linux@fluff.org, w.sang@pengutronix.de,
linux-kernel@vger.kernel.org, lenb@kernel.org,
rafael.j.wysocki@intel.com, broonie@opensource.wolfsonmicro.com,
grant.likely@secretlab.ca, linus.walleij@linaro.org,
mathias.nyman@linux.intel.com, linux-acpi@vger.kernel.org
Subject: Re: [PATCH 2/2] ACPI / platform: Initialize ACPI handles of platform devices in advance
Date: Mon, 19 Nov 2012 14:32:21 -0800 [thread overview]
Message-ID: <20121119223221.GB2250@kroah.com> (raw)
In-Reply-To: <1610515.dOb8aMkzLk@vostro.rjw.lan>
On Mon, Nov 19, 2012 at 09:44:21PM +0100, Rafael J. Wysocki wrote:
> On Monday, November 19, 2012 06:45:22 PM Rafael J. Wysocki wrote:
> > On Monday, November 19, 2012 06:32:06 PM Rafael J. Wysocki wrote:
> > > On Monday, November 19, 2012 08:23:34 AM Greg Kroah-Hartman wrote:
> > > > On Sun, Nov 18, 2012 at 10:13:59PM +0100, Rafael J. Wysocki wrote:
> > > > > From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
> > > > >
> > > > > The current platform device creation and registration code in
> > > > > acpi_create_platform_device() is quite convoluted. This function
> > > > > takes an ACPI device node as an argument and eventually calls
> > > > > platform_device_register_resndata() to create and register a
> > > > > platform device object on the basis of the information contained
> > > > > in that code. However, it doesn't associate the new platform
> > > > > device with the ACPI node directly, but instead it relies on
> > > > > acpi_platform_notify(), called from within device_add(), to find
> > > > > that ACPI node again with the help of acpi_platform_find_device()
> > > > > and acpi_platform_match() and then attach the new platform device
> > > > > to it. This causes an additional ACPI namespace walk to happen and
> > > > > is clearly suboptimal.
> > > > >
> > > > > Use the observation that it is now possible to initialize the ACPI
> > > > > handle of a device before calling device_add() for it to make this
> > > > > code more straightforward. Namely, add a new field to struct
> > > > > platform_device_info allowing us to pass the ACPI handle of interest
> > > > > to platform_device_register_full(), which will then use it to
> > > > > initialize the new device's ACPI handle before registering it.
> > > > > This will cause acpi_platform_notify() to use the ACPI handle from
> > > > > the device structure directly instead of using the .find_device()
> > > > > routine provided by the device's bus type. In consequence,
> > > > > acpi_platform_bus, acpi_platform_find_device(), and
> > > > > acpi_platform_match() are not necessary any more, so remove them.
> > > >
> > > > Why can't you use the platform_data * that is already in struct device
> > > > for this, instead of adding an acpi-specific field to the
> > > > platform_device structure?
> > >
> > > Hmm, I kind of don't understand the question. :-)
> > >
> > > Yes, we have acpi_handle in struct device (it actually is being added by a
> > > patch you've acked) and we use it. The whole point here is to streamline
> > > of the initalization of that field.
> > >
> > > > If not that, surely there is another field in struct device that you
> > > > could use that is free for this type of device?
> > >
> > > Yes, there is one and as I said above. :-)
> > >
> > > I'd be happy to use the struct device's field directly, but
> > > platform_device_register_full() allocates memory for the struct device in
> > > question, so that field actually doesn't exist yet when it is called.
> > >
> > > > > struct platform_device_info {
> > > > > struct device *parent;
> > > > > + void *acpi_handle;
> > > >
> > > > Oh, and if I do accept this, I want a "real" structure pointer here
> > > > please, not a void * "handle". That way is a slippery slope to the
> > > > Windows kernel programming style :)
> > >
> > > This is (void *), because the field being initialized is (void *). That field,
> > > in turn, is (void *), because ACPICA defines it that way. I thought about
> > > wrapping that in some more meaningless data type, but I did't find a way
> >
> > s/meaningless/meaningful/
>
> Well, perhaps I'll describe the problem to you, maybe you can help. :-)
>
> So, we want to have acpi_handle (or acpi_node) in addition to of_node in struct
> device (to be used in the analogous way plus for the execution of AML methods),
> but we don't want all users of device.h to have to include ACPI headers
> where the acpi_handle data type is defined. For this reason, we're using
> (void *) as its data type now, which let's say I'm not really happy with.
>
> I've been thinking about that for quite a while, though, and I'm not really
> sure what to do about that. Perhaps we could define something like
>
> struct acpi_dev_node {
> #ifdef CONFIG_ACPI
> void *handle;
> #endif
> };
>
> in device.h and use that as "struct acpi_dev_node acpi_node;" in struct device.
> Then, we could add the following macro
>
> #ifdef CONFIG_ACPI
> #define ACPI_HANDLE(dev) ((dev)->acpi_node.handle)
> #else
> #define ACPI_HANDLE(dev) (NULL)
> #endif
>
> and redefine DEVICE_ACPI_HANDLE(dev) as ((acpi_handle)ACPI_HANDLE(dev)).
>
> Then, the $subject patch would add "struct acpi_dev_node acpi_node;" to
> struct platform_device_info and use ACPI_HANDLE(dev) instead of accessing
> the struct device's field directly.
>
> I wonder what you think?
I like the hack of using an empty structure here, that's fine with me,
and makes me feel a little bit better about the whole "void *" stuff.
If you respin the patch with this, I'll ack it.
thanks,
greg k-h
next prev parent reply other threads:[~2012-11-19 22:31 UTC|newest]
Thread overview: 89+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-11-15 11:03 [PATCH v2 0/3] ACPI 5 support for GPIO, SPI and I2C Mika Westerberg
2012-11-15 11:03 ` [PATCH v2 1/3] gpio / ACPI: add ACPI support Mika Westerberg
2012-11-16 1:34 ` Rafael J. Wysocki
2012-11-16 6:54 ` Mika Westerberg
2012-11-16 8:05 ` Mika Westerberg
2012-11-16 8:12 ` Mika Westerberg
2012-11-16 10:02 ` Rafael J. Wysocki
2012-11-16 12:49 ` Mika Westerberg
2012-11-16 10:03 ` Rafael J. Wysocki
2012-11-15 11:03 ` [PATCH v2 2/3] spi / ACPI: add ACPI enumeration support Mika Westerberg
2012-11-16 10:06 ` Rafael J. Wysocki
2012-11-17 10:11 ` Rafael J. Wysocki
2012-11-17 10:18 ` Mika Westerberg
2012-11-15 11:03 ` [PATCH v2 3/3] i2c " Mika Westerberg
2012-11-16 10:09 ` Rafael J. Wysocki
2012-11-16 13:03 ` Jean Delvare
2012-11-16 13:21 ` Rafael J. Wysocki
2012-11-16 13:42 ` Jean Delvare
2012-11-16 14:17 ` Mika Westerberg
2012-11-16 15:23 ` Mika Westerberg
2012-11-16 16:47 ` Jean Delvare
2012-11-16 17:28 ` [PATCH v2 3/3 UPDATED] " Mika Westerberg
2012-11-16 18:12 ` Jean Delvare
2012-11-17 6:46 ` Bjorn Helgaas
2012-11-17 8:03 ` Mika Westerberg
2012-11-17 9:55 ` Mika Westerberg
2012-11-19 22:49 ` Bjorn Helgaas
2012-11-19 23:15 ` Rafael J. Wysocki
2012-11-19 23:28 ` Rafael J. Wysocki
2012-11-20 7:07 ` Mika Westerberg
2012-11-17 11:24 ` Rafael J. Wysocki
2012-11-18 15:55 ` Mika Westerberg
2012-11-18 21:10 ` [PATCH 0/2] ACPI: Simplify "glueing" to physical nodes (was: Re: [PATCH v2 3/3 UPDATED] i2c / ACPI: add ACPI enumeration support) Rafael J. Wysocki
2012-11-18 21:12 ` [PATCH 1/2] ACPI: Allow ACPI handles of devices to be initialized in advance Rafael J. Wysocki
2012-11-19 9:42 ` Mika Westerberg
2012-11-19 12:33 ` [Update][PATCH " Rafael J. Wysocki
2012-11-18 21:13 ` [PATCH 2/2] ACPI / platform: Initialize ACPI handles of platform devices " Rafael J. Wysocki
2012-11-19 16:23 ` Greg Kroah-Hartman
2012-11-19 17:32 ` Rafael J. Wysocki
2012-11-19 17:45 ` Rafael J. Wysocki
2012-11-19 20:44 ` Rafael J. Wysocki
2012-11-19 21:05 ` Mika Westerberg
2012-11-19 21:56 ` Rafael J. Wysocki
2012-11-19 22:32 ` Greg Kroah-Hartman [this message]
2012-11-19 22:44 ` Rafael J. Wysocki
2012-11-19 18:25 ` Rafael J. Wysocki
2012-11-19 22:31 ` Greg Kroah-Hartman
2012-11-19 22:45 ` Rafael J. Wysocki
2012-11-20 0:55 ` [Update][PATCH 0/3] ACPI: Simplify "glueing" to physical nodes Rafael J. Wysocki
2012-11-20 0:57 ` [Update][PATCH 1/3] ACPI: Allow ACPI handles of devices to be initialized in advance Rafael J. Wysocki
2012-11-20 0:59 ` [Update][PATCH 2/3] ACPI / driver core: Introduce struct acpi_dev_node and related macros Rafael J. Wysocki
2012-11-20 9:10 ` Mika Westerberg
2012-11-20 9:34 ` [Update 2][PATCH " Rafael J. Wysocki
2012-11-20 12:57 ` Mika Westerberg
2012-11-20 18:08 ` Greg Kroah-Hartman
2012-11-20 1:01 ` [Update][PATCH 3/3] ACPI / platform: Initialize ACPI handles of platform devices in advance Rafael J. Wysocki
2012-11-20 18:08 ` Greg Kroah-Hartman
2012-11-20 9:11 ` [Update][PATCH 0/3] ACPI: Simplify "glueing" to physical nodes Mika Westerberg
2012-11-20 9:31 ` Rafael J. Wysocki
2012-11-20 18:09 ` Greg Kroah-Hartman
2012-11-20 21:40 ` Rafael J. Wysocki
2012-11-16 20:02 ` [PATCH v2 3/3] i2c / ACPI: add ACPI enumeration support Rafael J. Wysocki
2012-11-16 20:09 ` Mika Westerberg
2012-11-16 20:18 ` Rafael J. Wysocki
2012-11-20 10:29 ` [PATCH v3 0/3] ACPI 5 support for GPIO, SPI and I2C Mika Westerberg
2012-11-20 10:29 ` [PATCH v3 1/3] gpio / ACPI: add ACPI support Mika Westerberg
2012-11-20 12:46 ` Rafael J. Wysocki
2012-11-20 10:29 ` [PATCH v3 2/3] spi / ACPI: add ACPI enumeration support Mika Westerberg
2012-11-20 13:05 ` Rafael J. Wysocki
2012-11-20 13:15 ` Mika Westerberg
2012-11-20 13:24 ` Rafael J. Wysocki
2012-11-20 10:29 ` [PATCH v3 3/3] i2c " Mika Westerberg
2012-11-20 13:06 ` Rafael J. Wysocki
2012-11-20 13:57 ` Mika Westerberg
2012-11-20 18:13 ` [PATCH v4 0/3] ACPI 5 support for GPIO, SPI and I2C Mika Westerberg
2012-11-20 18:13 ` [PATCH v4 1/3] gpio / ACPI: add ACPI support Mika Westerberg
2012-11-30 11:20 ` Grant Likely
2012-11-30 11:27 ` Rafael J. Wysocki
2012-11-20 18:13 ` [PATCH v4 2/3] spi / ACPI: add ACPI enumeration support Mika Westerberg
2012-11-30 11:24 ` Grant Likely
2012-11-30 11:36 ` Rafael J. Wysocki
2012-11-20 18:13 ` [PATCH v4 3/3] i2c " Mika Westerberg
2012-11-21 21:31 ` [PATCH v4 0/3] ACPI 5 support for GPIO, SPI and I2C Rafael J. Wysocki
2012-11-21 21:54 ` Jean Delvare
2012-11-23 11:39 ` Rafael J. Wysocki
2012-11-22 1:36 ` Mark Brown
2012-11-22 9:43 ` Linus Walleij
2012-11-22 10:03 ` Rafael J. Wysocki
2012-11-28 12:36 ` Mika Westerberg
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