Re: [PATCH 2/2] ARM: DTS: OMAP4: Add gpmc_fck clock node

[Tero Kristo <t-kristo@ti.com>]

On 02/17/2014 06:13 PM, Florian Vaussard wrote:
> Hi,
>
> On 02/17/2014 01:29 PM, Tero Kristo wrote:
>> On 02/17/2014 01:27 PM, Florian Vaussard wrote:
>>> Add the gpmc_fck clock, derived from l3_ick, and reference it from
>>> the GPMC node to get it correctly working.
>>>
>>> Signed-off-by: Florian Vaussard <florian.vaussard@epfl.ch>
>>> ---
>>>    arch/arm/boot/dts/omap4.dtsi           | 2 ++
>>>    arch/arm/boot/dts/omap44xx-clocks.dtsi | 6 ++++++
>>>    2 files changed, 8 insertions(+)
>>>
>>> diff --git a/arch/arm/boot/dts/omap4.dtsi b/arch/arm/boot/dts/omap4.dtsi
>>> index d3f8a6e..8a0cc71 100644
>>> --- a/arch/arm/boot/dts/omap4.dtsi
>>> +++ b/arch/arm/boot/dts/omap4.dtsi
>>> @@ -275,6 +275,8 @@
>>>                gpmc,num-waitpins = <4>;
>>>                ti,hwmods = "gpmc";
>>>                ti,no-idle-on-init;
>>> +            clocks = <&gpmc_fck>;
>>> +            clock-names = "fck";
>>>            };
>>>
>>>            uart1: serial@4806a000 {
>>> diff --git a/arch/arm/boot/dts/omap44xx-clocks.dtsi
>>> b/arch/arm/boot/dts/omap44xx-clocks.dtsi
>>> index c821ff5..ae2c441 100644
>>> --- a/arch/arm/boot/dts/omap44xx-clocks.dtsi
>>> +++ b/arch/arm/boot/dts/omap44xx-clocks.dtsi
>>> @@ -1036,6 +1036,12 @@
>>>            ti,index-power-of-two;
>>>        };
>>>
>>> +    gpmc_fck: gpmc_fck {
>>> +        #clock-cells = <0>;
>>> +        compatible = "ti,clkdm-gate-clock";
>>> +        clocks = <&l3_div_ck>;
>>> +    };
>>> +
>>
>> Why not implement a proper gate clock for CM_L3_2_GPMC_CLKCTRL? The
>> approach you have taken looks good to me otherwise.
>>
>
> So something like:
>
>          gpmc_fck: gpmc_fck {
>                  #clock-cells = <0>;
>                  compatible = "ti,gate-clock";
>                  clocks = <&l3_div_ck>;
>                  reg = <(CM_L3_2_GPMC_CLKCTRL)>;
>                  ti,bit-shift = <0>;
>          };
>
> ? I was not sure for gate-clock, as setting the bit will enable the
> clock only if the corresponding clock domain (CD_L3_2) is enabled as well.

Actually you may want not to add a gate clock for this, as this would 
result in duplicate control to the same bits... hwmod is already 
controlling this. Do you need the clkdm control for something? If not, 
you could just link the gpmc node directly to use l3_div_ck as the 
provider for its clock rate. Looking at the driver, I think you don't 
need it for anything else.

-Tero