Hi Daniel, Thank you for the patch.
On Mon, Jan 18, 2021 at 12:34:23AM +0000, Daniel Scally wrote: > In some ACPI tables we encounter, devices use the _DEP method to assert > a dependence on other ACPI devices as opposed to the OpRegions that the > specification intends. We need to be able to find those devices "from" > the dependee, so add a function to parse all ACPI Devices and check if > the include the handle of the dependee device in their _DEP buffer. > > Signed-off-by: Daniel Scally <[email protected]> > --- > Changes in v2: > - Used acpi_lpss_dep() as Andy suggested. > > drivers/acpi/utils.c | 34 ++++++++++++++++++++++++++++++++++ > include/acpi/acpi_bus.h | 2 ++ > 2 files changed, 36 insertions(+) > > diff --git a/drivers/acpi/utils.c b/drivers/acpi/utils.c > index 78b38775f18b..ec6a2406a886 100644 > --- a/drivers/acpi/utils.c > +++ b/drivers/acpi/utils.c > @@ -831,6 +831,18 @@ bool acpi_lpss_dep(struct acpi_device *adev, acpi_handle > handle) > return false; > } > > +static int acpi_dev_match_by_dep(struct device *dev, const void *data) > +{ > + struct acpi_device *adev = to_acpi_device(dev); > + const struct acpi_device *dependee = data; > + acpi_handle handle = dependee->handle; > + > + if (acpi_lpss_dep(adev, handle)) > + return 1; > + > + return 0; > +} > + I think I'd move this just before acpi_dev_get_next_dep_dev() to keep the two together. > /** > * acpi_dev_present - Detect that a given ACPI device is present > * @hid: Hardware ID of the device. > @@ -866,6 +878,28 @@ bool acpi_dev_present(const char *hid, const char *uid, > s64 hrv) > } > EXPORT_SYMBOL(acpi_dev_present); > > +/** > + * acpi_dev_get_next_dep_dev - Return next ACPI device dependent on input dev Maybe acpi_dev_get_next_dependent_dev() ? "dep" could mean either dependent or dependency. > + * @adev: Pointer to the dependee device > + * @prev: Pointer to the previous dependent device (or NULL for first match) > + * > + * Return the next ACPI device which declares itself dependent on @adev in > + * the _DEP buffer. > + * > + * The caller is responsible to call put_device() on the returned device. > + */ > +struct acpi_device *acpi_dev_get_next_dep_dev(struct acpi_device *adev, > + struct acpi_device *prev) > +{ > + struct device *start = prev ? &prev->dev : NULL; > + struct device *dev; > + > + dev = bus_find_device(&acpi_bus_type, start, adev, > acpi_dev_match_by_dep); Having to loop over all ACPI devices is quite inefficient, but if we need a reverse lookup, we don't really have a choice. We could create a reverse map, but I don't think it's worth it. > + > + return dev ? to_acpi_device(dev) : NULL; > +} > +EXPORT_SYMBOL(acpi_dev_get_next_dep_dev); I would have used EXPORT_SYMBOL_GPL. I'm not sure what the policy is in the ACPI subsystem, and it's also a personal choice. Reviewed-by: Laurent Pinchart <[email protected]> > + > /** > * acpi_dev_get_next_match_dev - Return the next match of ACPI device > * @adev: Pointer to the previous acpi_device matching this @hid, @uid and > @hrv > diff --git a/include/acpi/acpi_bus.h b/include/acpi/acpi_bus.h > index 02a716a0af5d..33deb22294f2 100644 > --- a/include/acpi/acpi_bus.h > +++ b/include/acpi/acpi_bus.h > @@ -683,6 +683,8 @@ static inline bool acpi_device_can_poweroff(struct > acpi_device *adev) > > bool acpi_dev_hid_uid_match(struct acpi_device *adev, const char *hid2, > const char *uid2); > > +struct acpi_device * > +acpi_dev_get_next_dep_dev(struct acpi_device *adev, struct acpi_device > *prev); > struct acpi_device * > acpi_dev_get_next_match_dev(struct acpi_device *adev, const char *hid, const > char *uid, s64 hrv); > struct acpi_device * -- Regards, Laurent Pinchart
