Hi, On 10/16/23 18:05, Shevchenko, Andriy wrote: > On Mon, Oct 16, 2023 at 06:44:21PM +0300, Wu, Wentong wrote: >>> From: gregkh@xxxxxxxxxxxxxxxxxxx >>> On Mon, Oct 16, 2023 at 03:05:09PM +0000, Wu, Wentong wrote: >>>>> From: Shevchenko, Andriy >>>>> On Mon, Oct 16, 2023 at 08:52:28AM +0300, Wu, Wentong wrote: > > ... > >>>>> But this does not confirm if you have such devices. Moreover, My >>>>> question about _CID per function stays the same. Why firmware is not using >>> it? >>>> >>>> Yes, both _ADR and _CID can stop growing list in the driver. And for >>>> _ADR, it also only require one ID per function. I don't know why BIOS >>>> team doesn't select _CID, but I have suggested use _ADR internally, >>>> and , to make things moving forward, the driver adds support for _ADR here >>> first. >>>> >>>> But you're right, _CID is another solution as well, we will discuss it >>>> with firmware team more. >>> >>> Should I revert this series now until this gets sorted out? >> >> Current _ADR support is a solution, I don't think _CID is better than _ADR to both >> stop growing list in driver and support the shipped hardware at the same time. >> >> Andy, what's your idea? > > In my opinion if _CID can be made, it's better than _ADR. As using _ADR like > you do is a bit of grey area in the ACPI specification. I.o.w. can you get > a confirmation, let's say, from Microsoft, that they will go your way for other > similar devices? > > Btw, Microsoft has their own solution actually using _ADR for the so called > "wired" USB devices. Is it your case? If so, I'm not sure why _HID has been > used from day 1... > > Also I suggest to wait for Hans' opinion on the topic. I definitely don't think we should revert the entire series since this supports actual hw which has already been shipping for years. But if the _ADR support is only there to support future hw and it is not even certain yet that that future hw is actually going to be using _ADR support then I believe that a follow-up patch to drop _ADR support for now is in order. We can then re-introduce it (revert the follow up patch) if future hw actually starts using _ADR support. Specifically what I'm suggesting is something like the following: diff --git a/drivers/usb/misc/usb-ljca.c b/drivers/usb/misc/usb-ljca.c index c9decd0396d4..e1bbaf964786 100644 --- a/drivers/usb/misc/usb-ljca.c +++ b/drivers/usb/misc/usb-ljca.c @@ -457,8 +457,8 @@ static void ljca_auxdev_acpi_bind(struct ljca_adapter *adap, u64 adr, u8 id) { struct ljca_match_ids_walk_data wd = { 0 }; - struct acpi_device *parent, *adev; struct device *dev = adap->dev; + struct acpi_device *parent; char uid[4]; parent = ACPI_COMPANION(dev); @@ -466,17 +466,7 @@ static void ljca_auxdev_acpi_bind(struct ljca_adapter *adap, return; /* - * get auxdev ACPI handle from the ACPI device directly - * under the parent that matches _ADR. - */ - adev = acpi_find_child_device(parent, adr, false); - if (adev) { - ACPI_COMPANION_SET(&auxdev->dev, adev); - return; - } - - /* - * _ADR is a grey area in the ACPI specification, some + * Currently LJCA hw does not use _ADR instead current * platforms use _HID to distinguish children devices. */ switch (adr) { As a follow-up patch to the existing series. Regards, Hans