linux-kernel - Re: [PATCH 1/2] i2c: consider devices with of_match

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Message-ID: <20200826052544.GA500@jagdpanzerIV.localdomain>
Date:   Wed, 26 Aug 2020 14:25:44 +0900
From:   Sergey Senozhatsky <sergey.senozhatsky@...il.com>
To:     Wolfram Sang <wsa@...nel.org>
Cc:     Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Mika Westerberg <mika.westerberg@...ux.intel.com>,
        linux-i2c@...r.kernel.org, linux-acpi@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] i2c: consider devices with of_match_table during i2c
 device probing

On (20/08/26 07:08), Wolfram Sang wrote:
> On Wed, Aug 26, 2020 at 01:29:37PM +0900, Sergey Senozhatsky wrote:
> > Unlike acpi_match_device(), acpi_driver_match_device() does
> > consider devices that provide of_match_table and performs
> > of_compatible() matching for such devices. The key point here is
> > that ACPI of_compatible() matching - acpi_of_match_device() - is
> > part of ACPI and does not depend on CONFIG_OF.
> > 
> > Consider the following case:
> > o !CONFIG_OF system
> > o probing of i2c device that provides .of_match_table, but no .id_table
> > 
> >  i2c_device_probe()
> >  ...
> >    if (!driver->id_table &&
> >        !i2c_acpi_match_device(dev->driver->acpi_match_table, client) &&
> >        !i2c_of_match_device(dev->driver->of_match_table, client)) {
> >        status = -ENODEV;
> >        goto put_sync_adapter;
> >    }
> > 
> > i2c_of_match_device() depends on CONFIG_OF and, thus, is always false.
> > i2c_acpi_match_device() does ACPI match only, no of_comtatible() matching
> > takes place, even though the device provides .of_match_table and ACPI,
> > technically, is capable of matching such device. The result is -ENODEV.
> > Probing will succeed, however, if we'd use .of_match_table aware ACPI
> > matching.
> > 
> > Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@...il.com>
> 
> We have currently this in for-current which is even removing
> i2c_acpi_match_device():
> 
> http://patchwork.ozlabs.org/project/linux-i2c/list/?series=196990&state=*

Oh, nice!
Can we go a bit further and use i2c_device_match() in i2c_device_probe()
instead of a mix of APIs from different subsystems?

E.g.

        if (!driver->id_table &&
-           !i2c_acpi_match_device(dev->driver->acpi_match_table, client) &&
-           !i2c_of_match_device(dev->driver->of_match_table, client)) {
+           !(client && i2c_device_match(&client->dev, dev->driver))) {
                status = -ENODEV;
                goto put_sync_adapter;
        }

	-ss