+ /* let the SoundWire master driver to its probe */
+ md->driver->probe(md, link);
So you are invoking driver probe here.. That is typically role of driver
core to do that.. If we need that, make driver core do that for you!
That reminds me I am missing match code for master driver...
There is no match for the master because it doesn't have an existence in
ACPI. There are no _ADR or HID that can be used, the only thing that exists
is the Controller which has 4 sublinks. Each master must be added by hand.
Also the SoundWire master cannot be enumerated or matched against a
SoundWire bus, since it controls the bus itself (that would be a chicken and
egg problem). The SoundWire master would need to be matched on a parent bus
(which does not exist for Intel) since the hardware is embedded in a larger
audio cluster that's visible on PCI only.
Currently for Intel platforms, the SoundWire master device is created by the
SOF driver (via the abstraction in intel_init.c).
That is okay for me, the thing that is bit confusing is having a probe
etc and no match.. (more below)..
So we seem to be somewhere is middle wrt driver probing here! IIUC this
is not a full master driver, thats okay, but then it is not
completely transparent either...
I was somehow thinking that the driver will continue to be
'platform/acpi/of' driver and master device abstraction will be
handled in the core (for example see how the busses like i2c handle
this). The master device is created and used to represent but driver
probing etc is not done
I2C controllers are typically PCI devices or have some sort of ACPI
description. This is not the case for SoundWire masters on Intel platforms,
Well the world is not PCI/ACPI... We have controllers which are DT
described and work in same manner as a PCI device.
Both DT and PCI would use a DIFFERENT matching on the parent bus, not a
matching provided by the SoundWire subsystem itself.
so even if I wanted to I would have no ability to implement any matching or
parent bus registration.
Also the notion of 'probe' does not necessarily mean that the device is
attached to a bus, we use DAI 'drivers' in ASoC and still have probe/remove
callbacks.
The "big" difference is that probe is called by core (asoc) and not by
driver onto themselves.. IMO that needs to go away.
What I did is not different from what existed already with platform
devices. They were manually created, weren't they?
And if you look at the definitions, we added additional callbacks since
probe/remove are not enough to deal with hardware restrictions:
For Intel platforms, we have a startup() callback which is only invoked once
the DSP is powered and the rails stable. Likewise we added an
'autonomous_clock_stop()' callback which will be needed when the Linux
driver hands-over control of the hardware to the DSP firmware, e.g. to deal
with in-band wakes in D0i3.
FWIW, the implementation here follows what was suggested for Greybus 'Host
Devices' [1] [2], so it's not like I am creating any sort of dangerous
precedent.
[1]
https://elixir.bootlin.com/linux/latest/source/drivers/greybus/es2.c#L1275
[2] https://elixir.bootlin.com/linux/latest/source/drivers/greybus/hd.c#L124
And if you look closely all this work is done by core not by drivers!
Drivers _should_ never do all this, it is the job of core to do that for
you.
Please look at the code again, you have a USB probe that will manually
call the GreyBus device creation.
static int ap_probe(struct usb_interface *interface,
const struct usb_device_id *id)
{
hd = gb_hd_create(&es2_driver, &udev->dev,
static struct usb_driver es2_ap_driver = {
.name = "es2_ap_driver",
.probe = ap_probe, <<< code above
.disconnect = ap_disconnect,
.id_table = id_table,
.soft_unbind = 1,
};
The master device probe suggested here is also called as part of the
parent SOF PCI device probe, same as this USB example. I really don't
see what your objection is, given that there is no way to deal with the
SoundWire controller as a independent entity for Intel platforms.
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