RE: [PATCH] iio: dac: ad5593r: Dynamically set AD5593R channel modes

From: "Hennerich, Michael" <Michael.Hennerich@analog.com>
To: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: AceLan Kao <acelan.kao@canonical.com>,
	"Ardelean, Alexandru" <alexandru.Ardelean@analog.com>,
	William Sung <william.sung@advantech.com.tw>,
	Lars-Peter Clausen <lars@metafoo.de>,
	Jonathan Cameron <jic23@kernel.org>,
	Hartmut Knaack <knaack.h@gmx.de>,
	Peter Meerwald-Stadler <pmeerw@pmeerw.net>,
	linux-iio <linux-iio@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Campion Kang <Campion.Kang@advantech.com.tw>
Subject: RE: [PATCH] iio: dac: ad5593r: Dynamically set AD5593R channel modes
Date: Wed, 2 Sep 2020 09:11:58 +0000	[thread overview]
Message-ID: <BN6PR03MB259650CEEEC9647AB5C9D8338E2F0@BN6PR03MB2596.namprd03.prod.outlook.com> (raw)
In-Reply-To: <CAHp75VdvnUsEf=fsRQRmyxQO=1m09M5U19GBtSPkjxSGA5cRBA@mail.gmail.com>

> -----Original Message-----
> From: Andy Shevchenko <andy.shevchenko@gmail.com>
> Sent: Mittwoch, 2. September 2020 10:52
> To: Hennerich, Michael <Michael.Hennerich@analog.com>
> Cc: AceLan Kao <acelan.kao@canonical.com>; Ardelean, Alexandru
> <alexandru.Ardelean@analog.com>; William Sung
> <william.sung@advantech.com.tw>; Lars-Peter Clausen <lars@metafoo.de>;
> Jonathan Cameron <jic23@kernel.org>; Hartmut Knaack <knaack.h@gmx.de>;
> Peter Meerwald-Stadler <pmeerw@pmeerw.net>; linux-iio <linux-
> iio@vger.kernel.org>; Linux Kernel Mailing List <linux-kernel@vger.kernel.org>;
> Campion Kang <Campion.Kang@advantech.com.tw>
> Subject: Re: [PATCH] iio: dac: ad5593r: Dynamically set AD5593R channel
> modes
> 
> [External]
> 
> On Wed, Sep 2, 2020 at 11:09 AM Hennerich, Michael
> <Michael.Hennerich@analog.com> wrote:
> > > From: Andy Shevchenko <andy.shevchenko@gmail.com>
> > > Sent: Montag, 31. August 2020 14:46
> > > On Mon, Aug 31, 2020 at 2:28 PM AceLan Kao
> > > <acelan.kao@canonical.com>
> > > wrote:
> 
> ...
> 
> > > P.S. Jonathan, it seems this driver has artificial ACPI HID. We
> > > probably have to remove it. However, ADS is indeed reserved for Analog
> Devices in PNP registry.
> > > Can we have AD's official answer on this?
> > > Cc'ing additional AD people.
> >
> > Agreed, this ID was chosen under the PNP ID Vendor Space for Analog Devices
> Inc.
> > Days back, I did a quick kernel grep, and there are many drivers which
> > use the 3-letter PNP ID as acpi_device_id. So, I thought this being not an issue.
> 
> No, no, the use of PNP ID is not an issue. The point is if the ID is artificial or
> official.
> 
> > I'm against removing it since I know people shipping this in their ACPI tables
> already.
> 
> I see. Can we consider this email as the official answer from AD that this ID is
> being allocated for this certain component?

To my knowledge only PNP/ACPI vendor IDs need to be registered with the UEFI 
ACPI working group. AD part numbers are unique. The ID chosen uses the 
part number prefixed with the PNP Vendor ID. ADxxxx->ADSxxxx
Please consider this as allocated.

> 
> > Regarding ACPI DSD customization, one way to do this is to move this into the
> BIOS.
> > This way the particular piece of HW can be customized rather than
> > manage HW connections in software.
> 
> Assuming the confirmation on the above, indeed, one may use ACPI HID with
> DSD properties in the firmware. Main purpose of PRP0001 is the
> *development* stage of the product at which a vendor should take care about
> allocation of proper ACPI IDs for the components in use. Yes, I know that this is
> not always feasible b/c some HW component vendors don't care about ACPI at
> all.
> 
> --
> With Best Regards,
> Andy Shevchenko

Best Regards,
Michael

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Michael Hennerich                       
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