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Message-ID: <1514584997.2743.107.camel@kernel.crashing.org> Date: Sat, 30 Dec 2017 09:03:17 +1100 From: Benjamin Herrenschmidt <benh@...nel.crashing.org> To: Stephen Boyd <sboyd@...eaurora.org> Cc: Joel Stanley <joel@....id.au>, Lee Jones <lee.jones@...aro.org>, Michael Turquette <mturquette@...libre.com>, linux-kernel@...r.kernel.org, linux-clk@...r.kernel.org, linux-arm-kernel@...ts.infradead.org, Andrew Jeffery <andrew@...id.au>, Jeremy Kerr <jk@...abs.org>, Rick Altherr <raltherr@...gle.com>, Ryan Chen <ryan_chen@...eedtech.com>, Arnd Bergmann <arnd@...db.de> Subject: Re: [PATCH v6 4/5] clk: aspeed: Register gated clocks 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. 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 ? Ben.
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