Dear Andrew Lunn,
On Sat, 17 Nov 2012 14:54:35 +0100, Andrew Lunn wrote:What is the ddr clock for? Does bad things happen if you turn it off?
Kirkwood has a similar clock, dunit, which i decided not to export,
since when you turn it off, the whole SoC locks up.
Well of course if you code run in DDR then it could be a problem. But
I think it could be useful to turn it off when going to suspend, it
the DDR can do self-refresh. In this case it should be possible to run
the code from SRAM or L2 Cache.
O.K. Just watch out for the lateinit call in the clock framework.
I don't think there is a problem with the dramclk and the lateinit call
of the clock framework. The dramclk is a fixed factor clock, and the
fixed factor clock driver does not implement the ->disable() operation.
And therefore, the clk_disable_unused() code executed as the lateinit
call will not be able to disable it:
if (__clk_is_enabled(clk)&& clk->ops->disable)
clk->ops->disable(clk->hw);
So I think we're quite safe with fixed rate clocks and fixed factor
clocks in that no-one can disable them :-)