Re: [PATCH v8 4/9] phy: fsl: Add Lynx 10G SerDes driver

[Stephen Boyd <sboyd@kernel.org>]

Quoting Sean Anderson (2022-12-08 07:36:45)
> On 12/6/22 21:17, Stephen Boyd wrote:
> > Quoting Sean Anderson (2022-11-01 16:27:21)
> >> On 11/1/22 16:10, Stephen Boyd wrote:
> >> >> 
> >> >> Oh, I remember why I did this. I need the reference clock for clk_hw_round_rate,
> >> >> which is AFAICT the only correct way to implement round_rate.
> >> >> 
> >> > 
> >> > Is the reference clk the parent of the clk implementing
> >> > clk_ops::round_rate()?
> >> 
> >> Yes. We may be able to produce a given output with multiple reference
> >> rates. However, the clock API provides no mechanism to say "Don't ask
> >> for the parent clock to be rate X, you just tried it and the parent
> >> clock can't support it." So instead, we loop over the possible reference
> >> rates and pick the first one which the parent says it can round to.
> >> 
> > 
> > Sorry, I'm lost. Why can't you loop over possible reference rates in
> > determine_rate/round_rate clk op here?
> 
> This is what I do currently, but you need to have the parent clock to do
> so. With your suggested method, we never actually get a struct clk(_hw)
> which we can query for rate support.

The clk_hw for the parent is given to the determine_rate clk_op in the
clk_rate_request structure. It's stored in the best_parent_hw pointer
when the determine_rate function is called. Does that work for you?