Re: [PATCH 1/2] i2c: consider devices with of_match_table during i2c device probing

Sergey Senozhatsky
2020-08-26T05:25:49Z

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@gmail.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