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
