On 12/30, Benjamin Herrenschmidt wrote: > On Tue, 2017-12-26 at 17:32 -0800, Stephen Boyd wrote: > > > I noticed we do have a few i2c based clock drivers... how are they ever > > > supposed to work ? i2c bus controllers are allowed to sleep and the i2c > > > core takes mutexes... > > > > We have clk_prepare()/clk_unprepare() for sleeping suckage. You > > can use that, and i2c based clk drivers do that today. > > "suckage" ? Hehe ... the suckage should rather be stuff that cannot > sleep. Arbitrary latencies and jitter caused by too much code wanting > to be "atomic" when unnecessary are a bad thing.
Heh. Of course. > > In the case of clocks like the aspeed where we have to wait for a > rather long stabilization delay, way too long to legitimately do a non- > sleepable delay with a lock held, do we need to do everything in > prepare() then ? > Yes. If we have to wait a long time in the enable path it makes sense to move it to the prepare path instead, if possible. That way we avoid holding a spinlock for a long time. -- Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, a Linux Foundation Collaborative Project
