On Wednesday, December 2, 2020 4:51:59 PM CET Rafael J. Wysocki wrote: > On Wednesday, December 2, 2020 2:49:17 PM CET Rafael J. Wysocki wrote: > > On Sat, Nov 21, 2020 at 9:30 PM Hans de Goede <hdegoede@xxxxxxxxxx> wrote: > > > > > > Hi Rafael, > > > > > > A while ago (almost 2 years ago) I discussed an issue with you about > > > some devices, where some of the methods used during device-addition > > > (such as _HID) may rely on OpRegions of other devices: > > > > > > https://www.spinics.net/lists/linux-acpi/msg86303.html > > > > > > An example of this is the Acer Switch 10E SW3-016 model. The _HID method > > > of the ACPI node for the UART attached Bluetooth, reads GPIOs to detect > > > the installed wifi chip and update the _HID for the Bluetooth's ACPI node > > > accordingly. The current ACPI scan code calls _HID before the GPIO > > > controller's OpRegions are available, leading to the wrong _HID being > > > used and Bluetooth not working. > > > > > > Last week I bought a second hand Acer device, not knowing it was this > > > exact model. Since I now have access to affected hardware I decided to > > > take a shot at fixing this. > > > > > > In the discussion you suggested to split the acpi_bus_scan of the root > > > into 2 steps, first scan devices with an empty _DEP, putting other > > > acpi_handle-s on a list of deferred devices and then in step 2 scan the > > > rest. > > > > > > I'm happy to report that, at least on the affected device, this works > > > nicely. While working on this I came up with a less drastic way to > > > deal with this. As you will see in patch 4 of this series, I decided > > > to first add a more KISS method of deciding which devices to defer > > > to the second scan step by matching by HID. This has the disadvantage > > > of not being a generic solution. But it has the advantage of being a > > > solution which does not potentially regress other devices. > > > > > > Then in patch 5 I actually do add the option to defer or not based on > > > _DEP being empty. I've put this behind a kernel commandline option as > > > I'm not sure we should do this everywhere by default. At least no without > > > a lot more testing. > > > > > > Patch 6 fixes an issue with patch 5 which causes battery devices to stop > > > working. > > > > > > And patch 7 adds some extra HIDs to the list of HIDs which should be > > > ignored when checking if the _DEP list is empty from Linux' pov, iow > > > some extra HIDs which Linux does not bind to. > > > > > > Please let me know what you think about this patch-set. I would be happy > > > to see just patches 1-4 merged. > > > > I took patches 1 and 2, because IMO they are generally useful (I > > rewrote the changelogs to avoid mentioning the rest of the series > > though), but I have some reservations regarding the rest. > > > > First off, I'm not really sure if failing acpi_add_single_object() for > > devices with missing dependencies is a good idea. IIRC there is > > nothing in there that should depend on any opregions supplied by the > > other devices, so it should be safe to allow it to complete. That, in > > turn, will allow the flags in struct acpi_device to be used to mark > > the "deferred" devices without allocating more memory. > > > > Next, in theory, devices with dependencies may also appear during > > hotplug, so it would be prudent to handle that on every invocation of > > acpi_bus_scan() and not just when it runs for the root object. > > > > So my approach would be to allow the first namespace walk in > > acpi_bus_scan() to complete, change acpi_bus_attach() to optionally > > skip the devices with missing dependencies and return a result > > indicating whether or not it has set flags.visited for any devices and > > run it in a loop on the "root" device object until it says that no new > > devices have been "attached". > > > > Let me cut a prototype patch for that and get back to you. > > Maybe something like the patch below (untested). I borrowed a few items from > your patches, hopefully not a problem. > > The multiple passes idea would require using a static variable which would > be slightly inelegant, so this assumes that two passes should be sufficient. > An update. This one has been lightly tested, but it doesn't make any practical difference on the system where it was run AFAICS. I found a missing ! in acpi_scan_should_defer_attach() and then realized that looking for _ADR wasn't really necessary, because _ADR devices should not be affected by this in a meaningful way anyway (scan handlers and ACPI drivers match on the _HID and/or _CID basis and the status check/power up in __acpi_bus_attach() should be skipped for them, because they may be "glued" to their "physical" counterparts before this code runs even - looks like a bug). --- drivers/acpi/scan.c | 47 ++++++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 44 insertions(+), 3 deletions(-) Index: linux-pm/drivers/acpi/scan.c =================================================================== --- linux-pm.orig/drivers/acpi/scan.c +++ linux-pm/drivers/acpi/scan.c @@ -1979,12 +1979,42 @@ static int acpi_scan_attach_handler(stru return ret; } -static void acpi_bus_attach(struct acpi_device *device) +/* + * List of IDs for which we defer adding them to the second pass of the + * scanning, because some of their methods used during addition depend on + * OpRegions registered by the drivers for other ACPI devices. + */ +static const struct acpi_device_id acpi_defer_attach_ids[] = { + { "BCM2E5B", 0 }, /* Acer SW3-016 bluetooth vs GPIO OpRegs */ + {"", 0}, +}; + +static bool acpi_scan_should_defer_attach(struct acpi_device *adev) +{ + if (!acpi_match_device_ids(adev, acpi_defer_attach_ids)) + return true; + + return adev->dep_unmet > 0; +} + +static void __acpi_bus_attach(struct acpi_device *device, bool first_pass) { struct acpi_device *child; acpi_handle ejd; int ret; + if (first_pass) { + if (acpi_scan_should_defer_attach(device)) + return; + } else if (device->flags.visited) { + /* + * This is not the first pass in the given scan and the device + * has been "attached" already, so get to the children right + * away. + */ + goto ok; + } + if (ACPI_SUCCESS(acpi_bus_get_ejd(device->handle, &ejd))) register_dock_dependent_device(device, ejd); @@ -2031,12 +2061,23 @@ static void acpi_bus_attach(struct acpi_ ok: list_for_each_entry(child, &device->children, node) - acpi_bus_attach(child); + __acpi_bus_attach(child, first_pass); - if (device->handler && device->handler->hotplug.notify_online) + if (first_pass && device->handler && + device->handler->hotplug.notify_online) device->handler->hotplug.notify_online(device); } +static void acpi_bus_attach(struct acpi_device *device) +{ + /* + * Assume two passes to be sufficient to satisfy all of the operation + * region dependencies. + */ + __acpi_bus_attach(device, true); + __acpi_bus_attach(device, false); +} + void acpi_walk_dep_device_list(acpi_handle handle) { struct acpi_dep_data *dep, *tmp;
