Re: [PATCH] clk: rockchip: rk3399: add pll up and down when change pll freq

Xing,

On Tue, Aug 2, 2016 at 6:13 AM, Xing Zheng [off-list ref] wrote:

From: Elaine Zhang <redacted>

The suggestion that is from IC designer, the correct pll sequence setting
should be like these:
----
  set pll to slow mode or other plls
  set pll down
  set pll params
  set pll up
  wait pll lock status
  set pll to normal mode
----

Hence, there are potential risks that we need to fix:
rockchip_rk3399_wait_pll_lock - timeout waiting for pll to lock
rockchip_rk3399_pll_set_params - pll update unsucessful, trying to restore old params

I still don't understand how that groks with the statement in the TRM:

In most cases the PLL programming can be changed on-the-fly and the PLL will simply slew to the new frequency

That makes it sound like these PLLs are super great at dynamic updates.