On 2/25/16 10:59 AM, Lukas Wunner wrote:
Hi Pierre-Louis, Hi Vinod,
On Mon, Feb 22, 2016 at 09:23:31PM +0100, Lukas Wunner wrote:
On Mon, Feb 22, 2016 at 08:18:15AM -0600, Pierre-Louis Bossart wrote:
On 02/21/2016 02:17 AM, Takashi Iwai wrote:
On Sat, 20 Feb 2016 23:47:24 +0100,
Lukas Wunner wrote:
Hi Takashi,
On Fri, Jan 15, 2016 at 06:58:19AM +0100, Takashi Iwai wrote:
On Thu, 14 Jan 2016 22:05:03 +0100, Lukas Wunner wrote:
Hi Takashi,
the acpi_dev_present() API has now landed in Linus' tree.
Thus, after Linus' tree gets merged back into yours,
it would be possible to use the API in the Thinkpad hda drivers
as per the following patch.
I've also pushed it to GitHub in case anyone prefers
perusing it in a browser:
https://github.com/l1k/linux/commit/a1473d726b57eaf97c4de8812c5967603068e261
An ack for this patch was kindly provided by Hui Wang with:
Message-ID: <5653C291.9090607@xxxxxxxxxxxxx>
http://mailman.alsa-project.org/pipermail/alsa-devel/2015-November/100962.html
A back merge is ugly and I'd like to avoid it.
This is no urgent fix but rather a cleanup, right? If so, I'd
postpone this to 4.6.
I've noticed this patch isn't in one of your trees, so it looks
like it's not queued for 4.6 yet. If there are objections against
it please let me know. If there aren't, I'd like to gently remind
of the patch's existence.
Sorry for the delay, it's merged now.
heads-up: we've identified that the ACPI subsystem reports devices as
present even if they are explicitly disabled in the BIOS _STA routine.
we have a couple of WIP patches to work around this issue that is
blocking for some CHT-T devices, and they pretty much amount to a
revert and addition of an explicit presence test
Thanks for the heads-up. I'm confused though that you're sending this
in reply to the thinkpad_helper.c patch, I assume this only concerns
the ASoC patch?
As you've correctly observed, acpi_dev_present() only checks presence
of a HID in the namespace and does not invoke the _STA control method.
However the code that it replaced also only checked presence in the
namespace, so this is not an issue introduced by my patch but rather
one which was present all along.
If you need to check the "device is present" bit returned by _STA,
you need a pointer to the struct acpi_device. This will allow you
to call acpi_bus_get_status() and check its return value for
ACPI_STA_DEVICE_PRESENT.
We cannot easily add this to acpi_dev_present() because that function
no longer does an expensive namespace walk but rather a cheap list
iteration which does not yield a pointer to the struct acpi_device.
In the first version of acpi_dev_present() I was in fact doing a
namespace walk with acpi_get_devices() but Robert Moore objected
to that, calling it "truly brute force":
http://mailman.alsa-project.org/pipermail/alsa-devel/2015-November/101046.html
Hence if possible you should try to avoid that as well. You may
want to consider adding a helper to drivers/acpi/utils.c which
takes a HID and returns a struct acpi_device*, it might come in
handy for others as well.
Forgot to mention:
There's one driver where you currently check for the presence of a
specific ACPI device twice. It would probably be good if you could
eliminate the second check.
I've explained this in detail in an e-mail to linux-acpi in December
but only cc'ed Mark Brown as I wasn't sure who's responsible for the
driver: http://www.spinics.net/lists/linux-acpi/msg62068.html
Quote:
* 1 is a driver for a platform_device (cht_bsw_rt5645.c) which was
instantiated by atom/sst/sst_acpi.c. The driver is responsible
for two chips and differentiates between the two by detecting the
presence of a particular HID. It would be possible to refactor the
code so that atom/sst/sst_acpi.c passes down the matched HID to
cht_bsw_rt5645.c, then it wouldn't be necessary to match for a
second time. Also, the only difference between the two chipsets
seems to be a minute change in struct snd_soc_dapm_route, so I'm
wondering if it's necessary to differentiate between the chipsets
at all.
Yes we are aware of this.
But again we are not going to use acpi_dev_present() anyway since it
just doesn't filter out devices that aren't enabled by the BIOS, we need
additional functionality for this.
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