[PATCH v4 0/2] Read _SUB from ACPI to be able to identify firmware

From: Stefan Binding
Date: Tue Jun 28 2022 - 06:44:37 EST


CS35L41 has a DSP which is able to run firmware, as well as a tuning file.
Different systems may want to use different firmwares and tuning files, and
some firmwares/tunings may not be compatible with other systems.
To allow a system to select the correct fimware/tuning, we can read an _SUB
from the ACPI. This _SUB can then be used to uniquely identify the system
in the firmware/tuning file name.

Add a helper function which reads the _SUB, so this can be used by other
parts in the future.
Add support inside the CS35L41 ASoC driver to read this _SUB, and save it
appropriately.

Changes since v3:
- Fix 32 bit format string warning

Changes since v2:
- Fix error in function prototype

Changes since v1:
- Add length validation for SSID String
- Rename API
- Allocate memory inside API
- Use ACPI_HANDLE macro instead of ACPI_COMPANION
- Improve error handling


Stefan Binding (2):
ACPI: utils: Add api to read _SUB from ACPI
ASoC: cs35l41: Read System Name from ACPI _SUB to identify firmware

drivers/acpi/utils.c | 38 ++++++++++++++++++++++++++++++++++++++
include/linux/acpi.h | 6 ++++++
sound/soc/codecs/cs35l41.c | 24 ++++++++++++++++++++++++
3 files changed, 68 insertions(+)

--
2.25.1