[PATCH 1/3] Add a common struct clk

[Jassi Brar]

On Fri, Sep 17, 2010 at 9:24 AM, Jeremy Kerr <jeremy.kerr at canonical.com> wrote:
> Hi Jassi,
>
>> I am not sure about the scope of your assumed task, but I would still
>> like to bring
>> to your notice some points.
>>
>> IMHO any clock api that aims to be used by multiple platforms should be generic
>> more than this one. Let me explain.
>
> None of my patches change the clock API itself. The clock API is already
> in use on ARM (ie, multiple platforms) and seems to work for most cases.
>
>> Clocks that are simply output of MUX'es inherit the rate of the parent
>> clock - they do have
>> rate yet this API would return 0 (IIRUIC).
>
> The proposed clock infrastructure does not provide implementations for
> the clock operation functions (like get_rate, which you're referring to
> here). The behaviour of the clocks is dictated by each implementation of
> struct clk. For MUXes, the callback for clk->ops.get_rate would be
> something like:
>
> unsigned long clk_mux_get_rate(struct clk *clk)
> {
>        return clk_get_rate(to_clk_mux(clk)->parent);
> }
>
> - so it just returns the rate of the parent (not 0). However, if the
> clock implementation has a reason to return 0, it is free to do so.

IMHO, the API needs to define a more generic clock that covers the 'classic'
and mux'ed clock by same data structure.
That implies fixing the API and modify the drivers (if need be) rather than have
multiple implementations of API. Let platforms move to the new one at their own
pace.
But, as you said, this is perhaps a matter for different thread.

regards.