Hi Paul,
On 2020-04-26 5:56 a.m., Paul Cercueil wrote:
>
>
> Le ven. 24 avril 2020 à 22:34, H. Nikolaus Schaller <hns@xxxxxxxxxxxxx> a écrit :
>> From: Jonathan Bakker <xc-racer2@xxxxxxx>
>>
>> All s5pv210 devices have a PowerVR SGX 540 (revision 120) attached.
>>
>> There is no external regulator for it so it can be enabled by default.
>>
>> Signed-off-by: Jonathan Bakker <xc-racer2@xxxxxxx>
>> Signed-off-by: H. Nikolaus Schaller <hns@xxxxxxxxxxxxx>
>> ---
>> arch/arm/boot/dts/s5pv210.dtsi | 13 +++++++++++++
>> 1 file changed, 13 insertions(+)
>>
>> diff --git a/arch/arm/boot/dts/s5pv210.dtsi b/arch/arm/boot/dts/s5pv210.dtsi
>> index 2ad642f51fd9..abbdda205c1b 100644
>> --- a/arch/arm/boot/dts/s5pv210.dtsi
>> +++ b/arch/arm/boot/dts/s5pv210.dtsi
>> @@ -512,6 +512,19 @@ vic3: interrupt-controller@f2300000 {
>> #interrupt-cells = <1>;
>> };
>>
>> + gpu: gpu@f3000000 {
>> + compatible = "samsung,s5pv210-sgx540-120";
>> + reg = <0xf3000000 0x10000>;
>> + interrupt-parent = <&vic2>;
>> + interrupts = <10>;
>> + clock-names = "core";
>> + clocks = <&clocks CLK_G3D>;
>> +
>> + assigned-clocks = <&clocks MOUT_G3D>, <&clocks DOUT_G3D>;
>> + assigned-clock-rates = <0>, <66700000>;
>> + assigned-clock-parents = <&clocks MOUT_MPLL>;
>
> What are these clocks for, and why are they reparented / reclocked?
>
> Shouldn't they be passed to 'clocks' as well?
>
> -Paul
>
The G3D clock system can have multiple parents, and for stable operation
it's recommended to use the MPLL clock as the parent (which in turn
is actually a mux as well). MOUT_G3D is simply the mux for CLK_G3D
(SGX core clock), DOUT_G3D is the divider. DOUT_G3D could equally be CLK_G3D
(and probably should be, for readability) as CLK_G3D is simply the gate and
DOUT_G3D is the divider for it.
The SGX clock layout on S5PV210 looks something like this:
MOUT_MPLL -----------> MOUT_G3D ---> DOUT_G3D ---> CLK_G3D
(selectable parent clock) (mux) ---> (divider) ---> (gate)
This is fairly common for older Samsung SoCs, eg having a look at
arch/arm/boot/dts/exynos4210-universal_c210.dts you can see that
the FIMC clocks are parented to MPLL and have a rate set.
>> + };
>> +
>> fimd: fimd@f8000000 {
>> compatible = "samsung,s5pv210-fimd";
>> interrupt-parent = <&vic2>;
>> --
>> 2.25.1
>>
>
>
Thanks,
Jonathan
