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From: Andy Shevchenko <andy.shevchenko@gmail.com>
To: Jonathan Cameron <jic23@kernel.org>
Cc: Hans de Goede <hdegoede@redhat.com>,
	"Rafael J . Wysocki" <rjw@rjwysocki.net>,
	Len Brown <lenb@kernel.org>, Darren Hart <dvhart@infradead.org>,
	Andy Shevchenko <andy@infradead.org>,
	ACPI Devel Maling List <linux-acpi@vger.kernel.org>,
	Platform Driver <platform-driver-x86@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Hartmut Knaack <knaack.h@gmx.de>,
	Lars-Peter Clausen <lars@metafoo.de>,
	Peter Meerwald-Stadler <pmeerw@pmeerw.net>,
	linux-iio <linux-iio@vger.kernel.org>
Subject: Re: [PATCH v3 10/11] iio: light: cm32181: Add support for parsing CPM0 and CPM1 ACPI tables
Date: Sun, 3 May 2020 19:25:20 +0300	[thread overview]
Message-ID: <CAHp75Vdt+shL3yXHfct17DUHdRBBrCzC4vBjQL8YHbimFefV7A@mail.gmail.com> (raw)
In-Reply-To: <20200503122237.4af34181@archlinux>

On Sun, May 3, 2020 at 2:22 PM Jonathan Cameron <jic23@kernel.org> wrote:
> On Tue, 28 Apr 2020 19:29:22 +0200
> Hans de Goede <hdegoede@redhat.com> wrote:

...

> > This was tested on the following models: Acer Switch 10 SW5-012 (CM32181)
> > Asus T100TA (CM3218), Asus T100CHI (CM3218) and HP X2 10-n000nd (CM32181).
>
> I assume it's far too much to hope this CPM0 / CPM1 stuff is actually defined
> in a spec anywhere?
>
> There are standard way of adding vendor specific data blobs to ACPI and this
> isn't one of them (unless I'm missing something).  People need to beat
> up vendors earlier about this stuff.
>
> Grumble over...
>
> Code looks fine to me, but I'd like an ACPI review ideally.

ACPI didn't cover embedded world and has the following issues
a) where it should be strict (like how many I2CSerialBus() resources
can be given and for what type of devices, etc), it doesn't
b) they need to provides better validation tools, but they didn't
c) it's still windows oriented :-(

Above is custom extension on how to add device properties (and note,
we have now _DSD() and still we have some M$ way of thinking how to
use them).

Since the above approach is in the wild, I'm afraid we have not many
possibilities here (each of them with own problems):
1/ shout at vendors to use ACPI properly and simple don't by broken
hardware (rather firmware)
2/ try to support custom changes (may lead to several approaches for
the same thing)
3/ create a lot of board files (something in between 1/ and 2/)

As a result:
1/ is obviously a best one, but I think it's an utopia.
2/ in practice we don't have many deviations (luckily OEMs are quite
lazy to modify reference BIOSes and often reuse existing approaches)
3/ may not work, because on cheap laptops the means of distinguishing
them (like DMI strings) may also been broken.

-- 
With Best Regards,
Andy Shevchenko

  reply	other threads:[~2020-05-03 16:25 UTC|newest]

Thread overview: 23+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-04-28 17:29 [PATCH v3 01/11] iio: light: cm32181: Switch to new style i2c-driver probe function Hans de Goede
2020-04-28 17:29 ` [PATCH v3 02/11] iio: light: cm32181: Add support for ACPI enumeration Hans de Goede
2020-04-28 17:29 ` [PATCH v3 03/11] iio: light: cm32181: Add some extra register defines Hans de Goede
2020-04-28 17:29 ` [PATCH v3 04/11] iio: light: cm32181: Add support for the CM3218 Hans de Goede
2020-05-03 10:59   ` Jonathan Cameron
2020-05-04  9:49     ` Hans de Goede
2020-05-04 10:23       ` Jonathan Cameron
2020-04-28 17:29 ` [PATCH v3 05/11] iio: light: cm32181: Clean up the probe function a bit Hans de Goede
2020-05-03 11:00   ` Jonathan Cameron
2020-04-28 17:29 ` [PATCH v3 06/11] iio: light: cm32181: Handle CM3218 ACPI devices with 2 I2C resources Hans de Goede
2020-05-03 11:04   ` Jonathan Cameron
2020-05-04  9:52     ` Hans de Goede
2020-04-28 17:29 ` [PATCH v3 07/11] iio: light: cm32181: Change reg_init to use a bitmap of which registers to init Hans de Goede
2020-04-28 17:29 ` [PATCH v3 08/11] iio: light: cm32181: Use units of 1/100000th for calibscale and lux_per_bit Hans de Goede
2020-04-28 17:29 ` [PATCH v3 09/11] iio: light: cm32181: Make lux_per_bit and lux_per_bit_base_it runtime settings Hans de Goede
2020-04-28 17:29 ` [PATCH v3 10/11] iio: light: cm32181: Add support for parsing CPM0 and CPM1 ACPI tables Hans de Goede
2020-05-03 11:22   ` Jonathan Cameron
2020-05-03 16:25     ` Andy Shevchenko [this message]
2020-05-04  9:40       ` Jonathan Cameron
2020-05-04  9:57     ` Hans de Goede
2020-04-28 17:29 ` [PATCH v3 11/11] iio: light: cm32181: Fix integartion time typo Hans de Goede
2020-05-03 10:54 ` [PATCH v3 01/11] iio: light: cm32181: Switch to new style i2c-driver probe function Jonathan Cameron
2020-05-04  9:46   ` Hans de Goede

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