Re: [RFC] i2c: Revert back to old device naming for ACPI enumerated I2C slaves

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Hi
On 10/10/2015 12:47 AM, Wolfram Sang wrote:
On Fri, Oct 02, 2015 at 12:27:16PM +0300, Jarkko Nikula wrote:
On 10/01/2015 11:37 PM, Wolfram Sang wrote:
Do you foresee troubles already? I am still in favour of a symlink.

I haven't looked at this for a while but one problem was that devices/
directory belongs to private structure of struct bus_type and in order to
create a symlink there it needs to done in drivers/base/bus.c:
bus_add_device() which felt quite hackish to me.

This is just a quick prototype and untested; but I did something similar
in the i2c-mux code:

diff --git a/drivers/i2c/i2c-core.c b/drivers/i2c/i2c-core.c
index 5f89f1e3c2f24f..715dca57ba68fd 100644
--- a/drivers/i2c/i2c-core.c
+++ b/drivers/i2c/i2c-core.c
@@ -970,13 +970,15 @@ static void i2c_dev_set_name(struct i2c_adapter *adap,
  {
  	struct acpi_device *adev = ACPI_COMPANION(&client->dev);

-	if (adev) {
-		dev_set_name(&client->dev, "i2c-%s", acpi_dev_name(adev));
-		return;
-	}
-
  	dev_set_name(&client->dev, "%d-%04x", i2c_adapter_id(adap),
  		     i2c_encode_flags_to_addr(client));
+
+	if (adev) {
+		char symlink_name[256];
+
+		snprintf(symlink_name, sizeof(symlink_name), "i2c-%s", acpi_dev_name(adev));
+		sysfs_create_link(&client->dev.kobj, &adap->dev.kobj, symlink_name);
+	}
  }

  /**

Shouldn't something like this be enough?

Not really. It would create the symlink under the device not under /sys/bus/i2c/devices/. Please note the sysfs_create_link() must be called after device_register(). I moved the symlink creation into i2c_new_device() for the example below.

Now:

/sys/bus/i2c/devices/i2c-ATML3432:00 -> ../../../devices/pci0000:00/0000:00:15.1/i2c_designware.1/i2c-9/i2c-ATML3432:00

After modified patch:

/sys/bus/i2c/devices/9-004c -> ../../../devices/pci0000:00/0000:00:15.1/i2c_designware.1/i2c-9/9-004c

which has now the symlink pointing to adapter

/sys/devices/pci0000:00/0000:00:15.1/i2c_designware.1/i2c-9/9-004c/
i2c-ATML3432:00 -> ../../i2c-9

We would need a following symlink but I didn't figure out how to do it without touching drivers/base/bus.c.

/sys/bus/i2c/devices/i2c-ATML3432:00 -> 9-004c

Symlinks there are added/removed by using &bus->p->devices_kset->kobj where p is a private for driver core only.

--
Jarkko
--
To unsubscribe from this list: send the line "unsubscribe linux-acpi" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html



[Index of Archives]     [Linux IBM ACPI]     [Linux Power Management]     [Linux Kernel]     [Linux Laptop]     [Kernel Newbies]     [Share Photos]     [Security]     [Netfilter]     [Bugtraq]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Samba]     [Video 4 Linux]     [Device Mapper]     [Linux Resources]

  Powered by Linux