On 12-05-20, 12:01, Pierre-Louis Bossart wrote:
There isn't any known implementation with more than one controller.
But then it can come in "future" right. So lets try to make it future proof by not using the link_id (we can expose that as a sysfs if people want to know). So a global unique id needs to allocated (hint: idr or equivalent) and used as master_id
Can you clarify if you are asking for a global ID for Intel/ACPI platforms, or for DT as well? I can't figure out from the soundwire-controller.yaml definitions if there is already a notion of unique ID.
If ACPI was unique, then I was planning to update the definition below to include that. Given that it is not the case, let's make it agnostic to underlying firmware.
I am not sure I understand how this would be done.
The call sequence is
sdw_bus_master_add(bus) sdw_master_device_add(bus, parent, fw_node)
At the bus level, we don't have any information on which controller the bus is related to.
This should be done inside the sdw_bus. controller should not care about this IMO.
We'd need to add an argument to sdw_bus_master_add() and have the controller unique ID be allocated outside of the SoundWire core, hence my question on whether the DT definition should not be extended.
And btw I don't think it makes sense to add a new definition for Intel. We already have a notion of HDaudio bus->idx that's set to zero since we don't have a case for multiple HDaudio controllers.
if we ever do have more than once controller, then we should rely on HDaudio bus->idx as the identifier and not create one specifically for SoundWire - which means as I mentioned above passing an argument and not defining a controller ID in the SoundWire core.
I was thinking of following code in bus.c
static DEFINE_IDA(sdw_ida);
static sdw_get_id(struct sdw_bus *bus) { int rc = ida_alloc(&sdw_ida, GFP_KERNEL);
if (rc < 0) return rc;
bus->id = rc; return 0; }
int sdw_add_bus_master(struct sdw_bus *bus) { ...
ret = sdw_get_id(bus);
... }
void sdw_delete_bus_master(struct sdw_bus *bus) { da_free(&sdw_ida, bus->id); }
This way you get a unique master number across all devices and this has nothing to do with link/of ids and is used for numbering masters in sysfs uniquely.
HTH