> From: Shevchenko, Andriy > On Mon, Oct 16, 2023 at 08:52:28AM +0300, Wu, Wentong wrote: > > > On 10/13/23 22:05, Shevchenko, Andriy wrote: > > > > On Thu, Oct 12, 2023 at 01:14:23PM +0200, Hans de Goede wrote: > > <snip> > > > > >> Ah ok, I see. So the code: > > > >> > > > >> 1. First tries to find the matching child acpi_device for the > > > >> auxdev by ADR > > > >> > > > >> 2. If 1. fails then falls back to HID + UID matching > > > >> > > > >> And there are DSDTs which use either: > > > >> > > > >> 1. Only use _ADR to identify which child device is which, like the example > > > >> DSDT snippet from the commit msg. > > > >> > > > >> 2. Only use _HID + _UID like the 2 example DSDT snippets from me > > > >> email > > > >> > > > >> But there never is a case where both _ADR and _HID are used at > > > >> the same time (which would be an ACPI spec violation as Andy said). > > > >> > > > >> So AFAICT there is no issue here since _ADR and _HID are never > > > >> user at the same time and the commit message correctly describes > > > >> scenario 1. from above, so the commit message is fine too. > > > >> > > > >> So I believe that we can continue with this patch series in its > > > >> current v20 form, which has already been staged for going into > > > >> -next by Greg. > > > >> > > > >> Andy can you confirm that moving ahead with the current version > > > >> is ok ? > > > > > > > > Yes as we have a few weeks to fix corner cases. > > > > > > > > What I'm worrying is that opening door for _ADR that seems never > > > > used is kinda an overkill here (resolving non-existing problem). > > > > > > I assume that there actually some DSDTs using the _ADR approach and > > > that this support is not there just for fun. > > > > right, it's not for fun, we use _ADR here is to reduce the maintain > > effort because currently it defines _HID for every new platform and > > the drivers have to be updated accordingly, while _ADR doesn't have that > problem. > > 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. > In that case you need only one ID per function in the driver (it might require some > IDs in the _HID, I don't remember that part of the spec by heart, i.e. if _CID can be > only provided with existing _HID or not). > > > > Wentong, can you confirm that the _ADR using codepaths are actually > > > used on some hardware / with some DSDTs out there ? > > > > what I can share is that we will see. > > > > > > Looking at the design of the > > > > driver I'm not sure why ACPI HIDs are collected somewhere else > > > > than in the respective drivers. > > > > AFAIK, auxiliary bus doesn't support parsing fwnodes currently. > > Probably we can support it for auxiliary bus in another patch. > > This is good idea! > > > > > > And looking at the ID lists themselves I am not sure why the > > > > firmware of the respective hardware platforms are not using > > > _CID. > > > > I think firmware can select _CID as well, but the shipped hw doesn't > > use _CID, the driver has to make sure the shipped hw working as well. > > And switching to _CID for the shipped hw is not easy, and it has to change > windows driver as well. > > I understand, but at least you may stop growing list in the driver. Yes, > And actually using separate IDs for multifunctional device seems not ideal > solution to me. Agree, I will consider _CID more, but currently to avoid this and also support shipped hardware, _ADR is at least a choice. BR, Wentong > > > This is a USB device which has 4 functions: > > Yes, I understand this part, but thank you for elaboration about auxbus, which > seems lack of needed support. And I would really like to see someone adds it > there. > > > > 1. GPIO controller > > > 2. I2C controller 1 > > > 3. I2C controller 2 > > > 4. SPI controller > > > > > > The driver for the main USB interface uses the new auxbus to create > > > 4 child devices. The _ADR or if that fails _HID + _UID matching is > > > done to find the correct acpi_device child of the acpi_device which > > > is the ACPI-companion of the main USB device. > > > > > > After looking up the correct acpi_device child this is then set as > > > the fwnode / ACPI-companion of the auxbus device created for that function. > > > > > > Having the correct fwnode is important because other parts of the > > > DSDT reference this fwnode to specify GPIO / I2C / SPI resources and > > > if the fwnode of the aux-device is not set correctly then the > > > resources for other devices referencing it (typically a camera > > > sensor) can not be found. > > > > > > As for why the driver for the auxbus devices / children do not use > > > HID matching, AFAIK the auxbus has no support for using ACPI (or DT) > > > matching for aux-devices and these drivers need to be > > > auxiliary_driver's and bind to the auxbus device and not to a > > > platform_device instantiated for the acpi_device since they need the auxbus > device to access the USB device. > > > > Yes, total agree. Thanks > > -- > With Best Regards, > Andy Shevchenko >
