On Thu, Oct 29, 2020 at 10:26:56PM +0200, Andy Shevchenko wrote: > On Thu, Oct 29, 2020 at 10:21 PM Laurent Pinchart wrote: > > On Mon, Oct 26, 2020 at 06:10:50PM +0200, Andy Shevchenko wrote: > > > On Sat, Oct 24, 2020 at 12:37:02PM +0300, Laurent Pinchart wrote: > > > > On Sat, Oct 24, 2020 at 09:50:07AM +0100, Dan Scally wrote: > > > > > On 24/10/2020 02:24, Laurent Pinchart wrote: > > > > > > On Mon, Oct 19, 2020 at 11:59:03PM +0100, Daniel Scally wrote: > > > > > > > > >> + adev = acpi_dev_get_first_match_dev(supported_devices[i], NULL, -1); > > > > > > > > > > > > What if there are multiple sensor of the same model ? > > > > > > > > > > Hmm, yeah, that would be a bit of a pickle. I guess the newer > > > > > smartphones have multiple sensors on the back, which I presume are the > > > > > same model. So that will probably crop up at some point. How about > > > > > instead I use bus_for_each_dev() and in the applied function check if > > > > > the _HID is in the supported list? > > > > > > > > Sounds good to me. > > > > > > > > > >> + if (!adev) > > > > > >> + continue; > > > > > > Please, don't. > > > > > > If we have so weird ACPI tables it must be w/a differently. The all, even badly > > > formed, ACPI tables I have seen so far are using _UID to distinguish instance > > > of the device (see second parameter to the above function). > > > > > > If we meet the very broken table I would like rather to know about, then > > > silently think ahead what could be best. > > > > > > I.o.w. don't change this until we will have a real example of the problematic > > > firmware. > > > > I'm not sure to follow you. Daniel's current code loops over all the > > supported HID (as stored in the supported_devices table), and then gets > > the first ACPI device for each of them. If multiple ACPI devices exist > > with the same HID, we need to handle them all, so enumerating all ACPI > > devices and checking whether their HID is one we handle seems to be the > > right option to me. > > Devices with the same HID should be still different by another > parameter in ACPI. The above mentioned call just uses the rough > estimation for relaxed conditions. If you expect more than one device > with the same HID how do you expect to distinguish them? The correct > way is to use _UID. It may be absent, or set to a value. And this > value should be unique (as per U letter in UID abbreviation). That > said, the above is good enough till we find the firmware with the > above true (several devices with the same HID). Until then the code is > fine. I expect those devices with the same _HID to have different _UID values, yes. On the systems I've seen so far, that assumption is not violated, and I don't think we need to already plan how we will support systems where multiple devices would have the same _HID and _UID (within the same scope). There's no disagreement there. My point is that supported_devices stores HID values, and doesn't care about UID. The code loops over supported_devices, and for each entry, calls acpi_dev_get_first_match_dev() and process the ACPI devices returned by that call. We thus process at most one ACPI device per HID, which isn't right. -- Regards, Laurent Pinchart
