Re: [PATCH 4/5] clk: samsung: Add support for EPLL on exynos5410

[Sylwester Nawrocki <s.nawrocki@samsung.com>]

On 08/30/2016 12:36 PM, Krzysztof Kozlowski wrote:
> On 08/22/2016 06:31 PM, Sylwester Nawrocki wrote:
>> This patch adds code instantiating the EPLL, which is used as the
>> audio subsystem's root clock.
>> The requirement to specify the external root clock in clocks property
>> is also added.
> 
> I think the requirement was there already but explained little bit
> differently:
> 19 External clock:
> 20
> 21 There is clock that is generated outside the SoC. It
> 22 is expected that it is defined using standard clock bindings
> 23 with following clock-output-name:
> 24
> 25  - "fin_pll" - PLL input clock from XXTI
>
> so you can just combine them. Driver now will require the fin_pll in two
> ways:
> 1. Old lookup by "fin_pll" name.
> 2. of_clk_get of yours.

I'm not sure what do you mean exactly, I'm also adding in this patch a sentence
right after the text as quoted above saying that:

"This clock should be listed in the clocks property of the controller node."

The description of the consumer clock (the main clock controller's parent clock)
was not in the binding so far, there is no "clocks" property in the list of
required properties.

>>  That ensures proper initialization order by explicitly
>> specifying dependencies in devicetree.  It prevents situations when the
>> SoC's clock controller driver has initialized, the external oscillator
>> clock is not yet registered and setting clock frequencies through
>> assigned-clock-rates property doesn't work properly due to unknown
>> external oscillator frequency.
>>
>> Signed-off-by: Sylwester Nawrocki <s.nawrocki@samsung.com>
>> ---
>>  .../devicetree/bindings/clock/exynos5410-clock.txt |  14 +++
>>  drivers/clk/samsung/clk-exynos5410.c               |  30 +++++-
>>  drivers/clk/samsung/clk-pll.c                      | 102 +++++++++++++++++++++
>>  drivers/clk/samsung/clk-pll.h                      |   1 +
>>  4 files changed, 145 insertions(+), 2 deletions(-)
>>
>> diff --git a/Documentation/devicetree/bindings/clock/exynos5410-clock.txt b/Documentation/devicetree/bindings/clock/exynos5410-clock.txt
>> index aeab635..2aefc07 100644
>> --- a/Documentation/devicetree/bindings/clock/exynos5410-clock.txt
>> +++ b/Documentation/devicetree/bindings/clock/exynos5410-clock.txt
>> @@ -12,6 +12,9 @@ Required Properties:
>>  
>>  - #clock-cells: should be 1.
>>  
>> +- clocks: should contain an entry specifying the root oscillator clock
>> +  on XXTI pin (fin_pll).
> 
> Combine with "external clock".

Do you mean rephrasing this to something like:

- clocks: should contain an entry specifying the external clock (fin_pll),
  i.e. the root clock on XXTI pin.

?

--
Thanks,
Sylwester