Messages in this thread | | | Date | Tue, 28 Mar 2023 18:17:16 +0300 | From | Vladimir Oltean <> | Subject | Re: [RFC PATCH net-next 2/2] net: dsa: mt7530: introduce MMIO driver for MT7988 SoC |
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On Tue, Mar 28, 2023 at 04:00:30PM +0100, Daniel Golle wrote: > On Tue, Mar 28, 2023 at 05:16:28PM +0300, Vladimir Oltean wrote: > > On Tue, Mar 28, 2023 at 02:08:18PM +0100, Daniel Golle wrote: > > > I agree that using regmap would be better and I have evaluated that > > > approach as well. As regmap doesn't allow lock-skipping and mt7530.c is > > > much more complex than xrs700x in the way indirect access to its MDIO bus > > > and interrupts work, using regmap accessors for everything would not be > > > trivial. > > > > > > So here we can of course use regmap_read_poll_timeout and a bunch of > > > readmap_write operations. However, each of them will individually acquire > > > and release the mdio bus mutex while the current code acquires the lock > > > at the top of the function and then uses unlocked operations. > > > regmap currently doesn't offer any way to skip the locking and/or perform > > > locking manually. regmap_read, regmap_write, regmap_update_bits, ... always > > > acquire and release the lock on each operation. > > > > What does struct regmap_config :: disable_locking do? > > I thought I can't use that on a per-operation base because the > instance of struct regmap_config itself isn't protected by any lock > and hence setting disable_locking=false before calling one of the > accessor functions may affect also other congruent calls to the > accessors which will then ignore locking and screw things up. > Please correct me if I'm wrong there.
It's not supposed to be used like that. You set disable_locking = true once, and take care of locking from the mt7530 driver. Not before every operation.
> Yet another way I thought about now could also be to have two regmap > instances, one for locked and one for unlocked accessed to the same > regmap_bus.
That would also be theoretically possible, but the above would be equivalent and would require a single regmap.
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