[PATCH 01/48] clk: at91: replace usleep() by udelay() calls

On Monday, June 13, 2016 5:24:09 PM CEST Alexandre Belloni wrote:

On 11/06/2016 at 00:30:36 +0200, Arnd Bergmann wrote :

quoted

On Saturday, June 11, 2016 12:03:04 AM CEST Alexandre Belloni wrote:

quoted

From: Cyrille Pitchen <redacted>

Fix the main and slow clock .prepare() implementations which used to call
usleep() when the scheduler wasn't ready yet.

Does this have to be called that early? It seems wasteful to always
call udelay() here, when these are functions that are normally
allowed to sleep.

So I've tested it and something like that would work:

        if (system_state < SYSTEM_RUNNING)
                udelay(osc->startup_usec);
        else
                usleep_range(osc->startup_usec, osc->startup_usec + 1);

I think that's reasonable in this case.

But I'm afraid it would be the first driver to actually do something
like that (however, it is already the only driver trying to sleep). 

We have a lot of drivers that call potentially sleeping function from
the .prepare callback, e.g. when they go to an i2c controller.

	Arnd