Re: [RFC/RFT v3 07/14] clk: meson: g12a: add notifiers to handle cpu clock change

Quoting Martin Blumenstingl (2019-07-02 16:28:55)

Hi Stephen, Hi Neil,

On Mon, Jul 1, 2019 at 11:13 AM Neil Armstrong [off-list ref] wrote:

quoted

In order to implement clock switching for the CLKID_CPU_CLK and
CLKID_CPUB_CLK, notifiers are added on specific points of the
clock tree :

cpu_clk / cpub_clk
|   \- cpu_clk_dyn
|      |  \- cpu_clk_premux0
|      |        |- cpu_clk_postmux0
|      |        |    |- cpu_clk_dyn0_div
|      |        |    \- xtal/fclk_div2/fclk_div3
|      |        \- xtal/fclk_div2/fclk_div3
|      \- cpu_clk_premux1
|            |- cpu_clk_postmux1
|            |    |- cpu_clk_dyn1_div
|            |    \- xtal/fclk_div2/fclk_div3
|            \- xtal/fclk_div2/fclk_div3
\ sys_pll / sys1_pll

This for each cluster, a single one for G12A, two for G12B.

Each cpu_clk_premux1 tree is marked as read-only and CLK_SET_RATE_NO_REPARENT,
to be used as "parking" clock in a safe clock frequency.

it seems that this is one case where the "coordinated clocks" feature
would come handy: [0]
Stephen, do you know if those patches stopped in March or if there's
still some ongoing effort to get them ready?

Derek told me yesterday he wants to work on it again, but I don't know
his timeline. If Derek doesn't reply here then maybe it can be picked up
by someone else.


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