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

From: Afzal Mohammed
Date: Tue Jun 14 2016 - 12:05:34 EST


Hi,

On Mon, Jun 13, 2016 at 05:24:09PM +0200, Alexandre Belloni wrote:
> On 11/06/2016 at 00:30:36 +0200, Arnd Bergmann wrote :

> > 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);
>
> 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).

tglx has suggested to modify clock core to handle a somewhat similar
kind of scenario (probably should work here too) and avoid driver
changes,

http://lkml.kernel.org/r/alpine.DEB.2.11.1606061448010.28031@nanos

Regards
afzal