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:

quoted

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 <redacted>

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