[alsa-devel] [PATCH v3 03/15] soc: tegra: Add Tegra PMC clock registrations into PMC driver

[Dmitry Osipenko]

11.12.2019 18:10, Peter De Schrijver пишет:
> On Tue, Dec 10, 2019 at 08:41:56PM +0300, Dmitry Osipenko wrote:
> 
> ..
> 
>>>
>>> PMC clock gate is based on the state of CLKx_ACCEPT_REQ and FORCE_EN
>>> like explained above.
>>>
>>> CLKx_ACCEPT_REQ is 0 default and FORCE_EN acts as gate to enable/disable
>>> EXTPERIPH clock output to PMC CLK_OUT_1/2/3.
>>
>> [and to enable OSC as well]
>>
>>> So I believe we need to register as MUX and Gate rather than as a single
>>> clock. Please confirm.
>>
>> 1. The force-enabling is applied to both OSC and EXTERN sources of
>> PMC_CLK_OUT_x by PMC at once.
>>
>> 2. Both of PMC's force-enabling and OSC/EXTERN selection is internal to PMC.
>>
>> Should be better to define it as a single "pmc_clk_out_x". I don't see
>> any good reasons for differentiating PMC's Gate from the MUX, it's a
>> single hardware unit from a point of view of the rest of the system.
>>
>> Peter, do you have any objections?
> 
> The reason to have separate gate and mux clocks, is to preserve compatibility
> with existing users.
> Otherwise the current users would need to figure out if there's a
> single clock or 2 clocks to configure. I don't think adding that code in
> each user is worth it only to have a sligthly nicer modelling of the
> hardware.

Could you please clarify what do you mean by the "existing users"?
AFAIK, nothing in kernel uses mux clocks.