Hi Andy On 30/11/2020 18:23, Andy Shevchenko wrote: > On Mon, Nov 30, 2020 at 01:31:25PM +0000, Daniel Scally wrote: >> ACPI devices declare themselves dependent on other devices via the _DEP >> buffer. Fetching the dependee from dependent is a matter of parsing >> _DEP, but currently there's no method to fetch dependent from dependee. >> Add one, so we can parse sensors dependent on a PMIC from the PMIC's >> acpi_driver. > Do I understand correctly that it's an existing table provided by firmware > that > (ab)uses _DEP in such way? Note, the specification doesn't tell we may use it > in this way, OTOH I don't remember if it strictly forbids such use. > > So, please elaborate in the commit message why you need this and pint out to > the 6.5.8 "_DEP (Operation Region Dependencies)" which clearly says about > OpRegions and that part already supported by ACPI in the Linux, if I'm not > mistaken, need to refresh my memory.
Laurent's reply is good explanation, but for example see my Lenovo Miix 510's DSDT: https://gist.githubusercontent.com/djrscally/e64d112180517352fa3392878b0f4a7d/raw/88b90b3ea4204fd7845257b6666fdade47cc2981/dsdt.dsl Search OVTI2680 and OVTI5648 for the cameras. Both are dependent on IN3472 devices (PMI0 and PMI1) which are the discrete type that we're attempting to handle here. > > ... > >> + handle = adev->handle; >> + >> + if (!acpi_has_method(handle, "_DEP")) >> + return 0; >> + >> + status = acpi_evaluate_reference(handle, "_DEP", NULL, &dep_handles); >> + if (ACPI_FAILURE(status)) >> + return 0; >> + >> + for (i = 0; i < dep_handles.count; i++) { >> + struct acpi_device_info *info; >> + >> + status = acpi_get_object_info(dep_handles.handles[i], &info); >> + if (ACPI_FAILURE(status)) >> + continue; >> + >> + if (info->valid & ACPI_VALID_HID) { >> + ret = acpi_bus_get_device(dep_handles.handles[i], >> &candidate); >> + if (ret || !candidate) { >> + kfree(info); >> + continue; >> + } >> + >> + if (candidate == dependee) { >> + acpi_dev_put(candidate); >> + kfree(info); >> + return 1; >> + } >> + >> + kfree(info); >> + } >> + } > Can you utilize (by moving to here and export for ACPI layer the > acpi_lpss_dep()? oooh, yes, I think I can. Thank you!
