driver-core: improve driver binding documentation

The driver binding documentation (still) mentions that "When a driver is
attached to a device, the device is inserted into the driver's list of
devices.".

While it is true that the driver-core keeps track of all the devices
that are attached to a driver, this is purely for internal purposes
(i.e. it is an implementation detail) and has no relevance for user
facing documentation.

In fact, it is even misleading, since it could be read as if it were
valid for driver implementations to keep track of all the devices bound
to it.

Instead, drivers operate on a per-device basis, with a separate
per-device instance created when the driver is bound to a device.

Hence, remove the mention of a driver's list of devices and instead add
some documentation of the relationship between drivers and devices.

Signed-off-by: Danilo Krummrich <dakr@kernel.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Message-ID: <20260115215718.6405-1-dakr@kernel.org>

Author: Danilo Krummrich

Documentation/driver-api/driver-model/binding.rst

@@ -53,9 +53,12 @@ class's register_dev callback.
 Driver
 ~~~~~~
 
-When a driver is attached to a device, the device is inserted into the
-driver's list of devices.
-
+When a driver is attached to a device, the driver's probe() function is
+called. Within probe(), the driver initializes the device and allocates
+and initializes per-device data structures. This per-device state is
+associated with the device object for as long as the driver remains bound
+to it. Conceptually, this per-device data together with the binding to
+the device can be thought of as an instance of the driver.
 
 sysfs
 ~~~~~