On Tue, 13 Jun 2023 15:59:14 +0200, Mark Brown wrote:
On Tue, Jun 13, 2023 at 09:36:34AM +0200, Takashi Iwai wrote:
This is an error from regache_sync_val(), and it indicates that the synced register is write-only; regcache_maple_sync() tries to sync all cached values no matter whether it's writable or not, then hitting this.
BTW I was just looking at reg_raw_update_once() and I can't figure out why it's trying to do what it's doing - it does a read to check if it's seen the register before and then does an _update_bits() if the register hasn't been cached yet, apparently trying suppress duplicate writes but possibly deliberately discarding changes to multiple bitfields in the same register. That's not what the non-regmap path does, it'll only discard noop changes to the same bitfield.
Yes, it's a quite hackish way of optimization of the initialization.
Since HD-audio codec has no known default values unlike normal codecs, it needs to initialize itself only at the first access, and this helper does it.
Takashi