tree f3c074daeb982201515a67a413bf30187a6c94e8
parent 2eb9d5ed62d3c3a4484c686af12d29a390ccf963
author Angel Pons <th3fanbus@gmail.com> 1719394164 +0200
committer Felix Held <felix-coreboot@felixheld.de> 1719577567 +0000

device/azalia_device.c: Always read-write GCAP

In the HD Audio Specification Rev. 1.0a, every bitfield in the GCAP
register is RO (Read Only). However, it is known that in some Intel
PCHs (e.g 6-series and 7-series, documents 324645 and 326776), some
of the bitfields in the GCAP register are R/WO (Read / Write Once).
GCAP is RO on 5-series PCHs; 8-series and 9-series PCHs have a lock
bit for GCAP elsewhere.

Lock GCAP by reading GCAP and writing back the same value. This has
no effect on platforms that implement GCAP as a RO register or lock
GCAP through a different mechanism.

Change-Id: Id61e6976a455273e8c681dbeb4bad35d57b1a8a2
Signed-off-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/83218
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Nico Huber <nico.h@gmx.de>