Re: [PATCH v5 0/8] ACPI overlays

[Rafael J. Wysocki]

On Friday, July 01, 2016 11:19:04 PM Octavian Purdila wrote:
> This patch set enables custom ACPI board configuration by adding
> mechanisms in the Linux kernel for loading user defined SSDTs.
> 
> In order to support ACPI open-ended hardware configurations we need a
> way to augment the ACPI configuration provided by the firmware
> image. A common example is connecting sensors on I2C / SPI buses on
> development boards.
> 
> Although this can be accomplished by creating a kernel platform driver
> or recompiling the firmware image with updated ACPI tables, neither is
> practical: the former proliferates board specific kernel code while
> the latter requires access to firmware tools which are often not
> publicly available.
> 
> Because ACPI supports external references in AML code a more practical
> way to augment firmware ACPI configuration is by dynamically loading
> user defined SSDT tables that contain the board specific information.
> 
> Currently it is possible to load SSDT overlays using the upgrade
> initrd mechanism introduced in 4.7. This patch series adds support for
> two more methods:
> 
> * From an EFI variable
> 
>  This is the preferred method, when EFI is supported on the platform,
>  because it allows a persistent, OS independent way of storing and
>  updating the user defined SSDTs. There is also work underway to
>  implement EFI support for loading user defined SSDTs and using this
>  method will make it easier to convert to the EFI loading mechanism
>  when that will arrive.
> 
> * From userspace via configfs
> 
>  This is useful when we want to defer the operation to userspace for
>  platform detection, loading the SSDTs from a custom partition, etc.
> 
> 
> Changes from v4:
> 
> * EFI: use ucs2_as_utf8 and memcmp to check if the variable name
>   matches the kernel command line parameter; fold the EFI ACPI table
>   load code in the iterator function
> 
> * I2C/SPI: add more information in the commit logs about how the
>   enumeration status is set and checked; also add a new check of the
>   enumerated status for the ACPI device remove reconfiguration
>   notification
> 
> Changes from v3:
> 
> * fix a bisectability issue reported by kbuild
> 
> * rework the enumeration fix to support PRP0001 enumeration; also,
>   introduce acpi_device_set/clear_enumerated() for clarity
> 
> * clear the enumerated status for acpi_device when the I2C/SPI clients
>   are removed (for example as a result of an adapter removal) to allow
>   the devices to be re-enumerated later
> 
> Changes from v2:
> 
> * fix a few issues caught by the kbuild test robot
> 
> * add more configfs table attributes
> 
> * removed the initrd based loading functionality from this patch set
>   as this can already be accomplished in 4.7 using the ACPI table
>   upgrade mechanism
> 
> * rebased to 4.7-rc3
> 
> Changes from v1:
> 
> * rebased on top of the ACPI install from initrd table functionality;
>   there is significant overlap between the 1st patch in this series
>   and these patch [1] from Lv - I kept it in this series until the
>   discussions around the taint and config option are resolved
> 
> * make sure EFI_RUNTIME_SERVICES are available before trying to use
>   EFI variables to load tables
> 
> * rework the ACPI reconfiguration notifications to work on device
>   granularity (device added or removed) instead of table granularity
>   (table loaded or unloaded)
> 
> * add support for table unloading / device removal
> 
> * note that the last patch is just a hack to be able to test the table
>   unload / device remove functionality, if someone wants to try out
>   this patch set
> 
> [1] https://patchwork.kernel.org/patch/8795931/
> 
> Octavian Purdila (8):
>   Documentation: acpi: add SSDT overlays documentation
>   acpi: fix enumeration (visited) flags for bus rescans
>   acpi: add support for ACPI reconfiguration notifiers
>   i2c: add support for ACPI reconfigure notifications
>   spi: add support for ACPI reconfigure notifications
>   efi: load SSTDs from EFI variables
>   acpi: add support for configfs
>   acpi: add support for loading SSDTs via configfs
> 
>  Documentation/ABI/testing/configfs-acpi |  36 +++++
>  Documentation/acpi/ssdt-overlays.txt    | 172 ++++++++++++++++++++
>  Documentation/kernel-parameters.txt     |   7 +
>  MAINTAINERS                             |   1 +
>  drivers/acpi/Kconfig                    |   9 ++
>  drivers/acpi/Makefile                   |   1 +
>  drivers/acpi/bus.c                      |   9 ++
>  drivers/acpi/configfs.c                 | 267 ++++++++++++++++++++++++++++++++
>  drivers/acpi/internal.h                 |   3 +
>  drivers/acpi/scan.c                     |  81 +++++++++-
>  drivers/acpi/sysfs.c                    |   6 +-
>  drivers/firmware/efi/efi.c              |  85 ++++++++++
>  drivers/i2c/i2c-core.c                  | 175 ++++++++++++++++-----
>  drivers/spi/spi.c                       | 100 +++++++++++-
>  include/linux/acpi.h                    |  36 +++++
>  15 files changed, 932 insertions(+), 56 deletions(-)
>  create mode 100644 Documentation/ABI/testing/configfs-acpi
>  create mode 100644 Documentation/acpi/ssdt-overlays.txt
>  create mode 100644 drivers/acpi/configfs.c

It looks like all patches in this series except for the [6/8] are good to go.

Do any of them depend on the [6/8]?

Thanks,
Rafael