linux-kernel - Re: [PATCH 18/18] ipu3: Add driver for dummy INT3472 ACPI device

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Message-ID: <20201201185122.GK4077@smile.fi.intel.com>
Date:   Tue, 1 Dec 2020 20:51:22 +0200
From:   Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
To:     Laurent Pinchart <laurent.pinchart@...asonboard.com>
Cc:     Dan Scally <djrscally@...il.com>,
        Jean-Michel Hautbois <jeanmichel.hautbois@...asonboard.com>,
        linux-kernel@...r.kernel.org, linux-acpi@...r.kernel.org,
        linux-gpio@...r.kernel.org, linux-i2c@...r.kernel.org,
        linux-media@...r.kernel.org, devel@...ica.org, rjw@...ysocki.net,
        lenb@...nel.org, gregkh@...uxfoundation.org,
        mika.westerberg@...ux.intel.com, linus.walleij@...aro.org,
        bgolaszewski@...libre.com, wsa@...nel.org, yong.zhi@...el.com,
        sakari.ailus@...ux.intel.com, bingbu.cao@...el.com,
        tian.shu.qiu@...el.com, mchehab@...nel.org, robert.moore@...el.com,
        erik.kaneda@...el.com, pmladek@...e.com, rostedt@...dmis.org,
        sergey.senozhatsky@...il.com, linux@...musvillemoes.dk,
        kieran.bingham+renesas@...asonboard.com, jacopo+renesas@...ndi.org,
        laurent.pinchart+renesas@...asonboard.com,
        jorhand@...ux.microsoft.com, kitakar@...il.com,
        heikki.krogerus@...ux.intel.com
Subject: Re: [PATCH 18/18] ipu3: Add driver for dummy INT3472 ACPI device

On Tue, Dec 01, 2020 at 08:36:16PM +0200, Laurent Pinchart wrote:
> On Tue, Dec 01, 2020 at 08:31:39PM +0200, Andy Shevchenko wrote:
> > On Mon, Nov 30, 2020 at 11:20:55PM +0000, Dan Scally wrote:
> > > On 30/11/2020 16:17, Jean-Michel Hautbois wrote:

...

> > > but the ACPI table doesn't define an I2CSerialBusV2 for it. Instead it's
> > > rolled under the sensor's entry, there's a second entry in _CRS for the
> > > sensor that matches the address of the new device:
> > > 
> > > 
> > >             Method (_CRS, 0, NotSerialized)  // _CRS: Current Resource Settings
> > >             {
> > >                 Name (SBUF, ResourceTemplate ()
> > >                 {
> > >                     I2cSerialBusV2 (0x0036, ControllerInitiated, 0x00061A80,
> > >                         AddressingMode7Bit, "\\_SB.PCI0.I2C2",
> > >                         0x00, ResourceConsumer, , Exclusive,
> > >                         )
> > >                     I2cSerialBusV2 (0x000C, ControllerInitiated, 0x00061A80,
> > >                         AddressingMode7Bit, "\\_SB.PCI0.I2C2",
> > >                         0x00, ResourceConsumer, , Exclusive,
> > >                         )
> > >                 })
> > >                 Return (SBUF) /* \_SB_.PCI0.CAM0._CRS.SBUF */
> > >             }
> > > 
> > > So that's another thing we need to work on. At the moment it doesn't
> > > exist as far as the kernel is concerned.
> > 
> > Maybe something along i2c-multi-instantiate can help here (maybe not).
> 
> It's two different devices really. That's also one of the "annoyances"
> related to this platform. The INT* HID for the camera sensor actually
> refers to a camera module, with VCM, EEPROM, ... On Chrome OS devices,
> the same HID refers to the camera sensor only. *sigh* :-(

But it's not a problem for i2c-multi-instantiate. It's kinda MFD approach for
I²C peripheral devices.

-- 
With Best Regards,
Andy Shevchenko