On Fri, Feb 13, 2015 at 04:35:36PM +0200, Tomi Valkeinen wrote:

On 12/02/15 15:41, Sascha Hauer wrote:

quoted

Tomis patch is based on the assumption that clk_set_rate(clk_round_rate(rate))
is equal to clk_round_rate(rate). So when this assumption is wrong then
it should simply be reverted.

When is it not equal?

I agree that doing clk_set_rate(clk, clk_round_rate(clk, rate)) is
pointless, but shouldn't it still work?

And we can forget about clk_round_rate. Without my patch, this would
behave oddly also:

rate = clk_get_rate(clk);
clk_set_rate(clk, rate);

The end result could be something else than 'rate'.

I agree that it's a bit odd, but I think it has to be like this.
Consider that you request a rate of 100Hz, but the clock can only
produce 99.5Hz, so due to rounding clk_round_rate() returns 99Hz.
Now when you request 99Hz from clk_set_rate() the 99.5Hz value
can't be used because it's too high.

Sascha

-- 
Pengutronix e.K.                           |                             |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |
Peiner Str. 6-8, 31137 Hildesheim, Germany | Phone: +49-5121-206917-0    |
Amtsgericht Hildesheim, HRA 2686           | Fax:   +49-5121-206917-5555 |