On 12/20/23 16:16, Charles Keepax wrote: > On Tue, Dec 19, 2023 at 06:08:15PM +0100, Pierre-Louis Bossart wrote: >> On 12/19/23 17:53, Mark Brown wrote: >>> On Tue, Dec 19, 2023 at 05:50:30PM +0100, Pierre-Louis Bossart wrote: >>>>> grep for regmap_.*async - cs_dsp.c is the upstream example in a driver, >>>>> or there's the rbtree cache sync code which uses a back door to go into >>>>> an async mode. Basically just variants of all the normal regmap I/O >>>>> calls with a _complete() call you can use to wait for everything to >>>>> happen. The implementation is a bit heavyweight since it was written to >>>>> work with fairly slow buses. >>> >>>> I spent a fair amount of time this afternoon trying to understand the >>>> regmap_async parts, and I am not following where in the code there is an >>>> ordering requirement/enforcement between async and sync usages. >>> >>> The only actual async implementation is SPI which processes things in >>> order of submission, the sync API wraps the async API. >>> >>>> Also is this just me spacing out or there is no regmap_raw_read_async()? >>> >>> Right, there was never any need. >> >> ok. I am starting to think that we could have a new type of regmap, say >> "regmap-sdw-bra", where the use of write_raw_async() would rely on the >> send/wait bus primitives, and write_raw() would fallback to the regular >> read/write commands. We'd need a mutual exclusion to prevent parallel >> async/sync access to the same regmap. >> >> In other words, "memory" areas that are used for firmware downloads >> would be moved to a different regmap with async capabilities and no >> caching support. > > I would be a little inclined to say leave adding a regmap for a > follow up series, whether we add it to the existing regmap or add > a new one, or whatever, it should all sit happily on top of the > API being added in this series. Makes it a little more contained > to focus on one area at a time, and leave this series as adding > core support for BRA. But that said, if we really want to I don't > feel mega strongly on this one. Right, I was probably going too far down in the details for a December 20 post. The point I was trying to make it seems there's consensus that regmap with the async parts would be the API used by SoundWire/ASoC codecs, and the regmap implementation would rely on the bus/host send/wait routines. The regmap stuff will need joint work with codec driver folks so it should indeed be done in a second step when the SoundWire bus/host parts are available. Put differently: is there any sustained objection to the proposal of extending regmap with async BRA transfers?
