[PATCH v4 3/4] dt-bindings: display: rockchip: Add schema for RK3588 HDMI TX Controller

[Cristian Ciocaltea]

On 8/22/24 12:38 AM, Heiko Stuebner wrote:
> 
> 
> Am 21. August 2024 23:28:55 MESZ schrieb Conor Dooley <conor at kernel.org>:
>> Cristian, Heiko,
>>
>> On Wed, Aug 21, 2024 at 11:38:01PM +0300, Cristian Ciocaltea wrote:
>>> On 8/21/24 6:07 PM, Conor Dooley wrote:
>>>> On Tue, Aug 20, 2024 at 11:12:45PM +0300, Cristian Ciocaltea wrote:
>>>>> On 8/20/24 7:14 PM, Conor Dooley wrote:
>>>>>> On Tue, Aug 20, 2024 at 03:37:44PM +0300, Cristian Ciocaltea wrote:
>>>>>>> On 8/19/24 7:53 PM, Conor Dooley wrote:
>>>>>>>> On Mon, Aug 19, 2024 at 01:29:30AM +0300, Cristian Ciocaltea wrote:
>>>>>>>>> +  rockchip,grf:
>>>>>>>>> +    $ref: /schemas/types.yaml#/definitions/phandle
>>>>>>>>> +    description:
>>>>>>>>> +      Most HDMI QP related data is accessed through SYS GRF regs.
>>>>>>>>> +
>>>>>>>>> +  rockchip,vo1-grf:
>>>>>>>>> +    $ref: /schemas/types.yaml#/definitions/phandle
>>>>>>>>> +    description:
>>>>>>>>> +      Additional HDMI QP related data is accessed through VO1 GRF regs.
>>>>>>>>
>>>>>>>> Why are these required? What prevents you looking up the syscons by
>>>>>>>> compatible?
>>>>>>>
>>>>>>> That is for getting the proper instance:
>>>>>>
>>>>>> Ah, that makes sense. I am, however, curious why these have the same
>>>>>> compatible when they have different sized regions allocated to them.
>>>>>
>>>>> Good question, didn't notice.  I've just checked the TRM and, in both
>>>>> cases, the maximum register offset is within the 0x100 range.  Presumably
>>>>> this is nothing but an inconsistency, as the syscons have been added in
>>>>> separate commits.
>>>>
>>>> Is that TRM publicly available? I do find it curious that devices sound
>>>> like they have different contents have the same compatible. In my view,
>>>> that is incorrect and they should have unique compatibles if the
>>>> contents (and therefore the programming model) differs.
>>>
>>> Don't know if there's an official location to get it from, but a quick
>>> search on internet shows a few repos providing them, e.g. [1].
>>>
>>> Comparing "6.14 VO0_GRF Register Description" at pg. 777 with "6.15 VO1_GRF
>>> Register Description" at pg. 786 (from Part1) reveals the layout is mostly
>>> similar, with a few variations though.
>>
>> Page references and everything, thank you very much. I don't think those
>> two GRFs should have the same compatibles, they're, as you say, similar
>> but not identical. Seems like a bug to me!
>>
>> Heiko, what do you think?
> 
> Yes, while the register names sound similar, looking at the bit
> definitions this evening revealed that they handle vastly different
> settings.
> 
> So I guess we should fix the compatibles. They are all about graphics
> stuff and HDMI actually is the first output, so right now WE can at least
> still claim the no-users joker ;-)

I couldn't find any driver doing a lookup for them by compatible, so I
think it's fine to fix them - should we go for "rockchip,rk3588-vo0-grf" and
"rockchip,rk3588-vo1-grf", respectively?

vo0_grf seems to be used by the usbdp phy nodes:

    usbdp_phy0: phy at fed80000 {
        compatible = "rockchip,rk3588-usbdp-phy";
        [...]
        rockchip,vo-grf = <&vo0_grf>;
        [...]

Same for "usbdp_phy1: phy at fed90000".

While vo1_grf is present in:

    vop: vop at fdd90000 {
        compatible = "rockchip,rk3588-vop";
        [...]
        rockchip,vo1-grf = <&vo1_grf>;
        [...]

I guess it's too late to drop them while updating the related drivers
accordingly, hence I wonder if we should keep using the phandles for this
HDMI thing as well, for consistency reasons.

Thanks,
Cristian

> Heiko
> 
>>
>>> [1] https://github.com/FanX-Tek/rk3588-TRM-and-Datasheet
>>>
>>>>>
>>>>>>> 	vo0_grf: syscon at fd5a6000 {
>>>>>>> 		compatible = "rockchip,rk3588-vo-grf", "syscon";
>>>>>>> 		reg = <0x0 0xfd5a6000 0x0 0x2000>;
>>>>>>> 		clocks = <&cru PCLK_VO0GRF>;
>>>>>>> 	};
>>>>>>>
>>>>>>> 	vo1_grf: syscon at fd5a8000 {
>>>>>>> 		compatible = "rockchip,rk3588-vo-grf", "syscon";
>>>>>>> 		reg = <0x0 0xfd5a8000 0x0 0x100>;
>>>>>>> 		clocks = <&cru PCLK_VO1GRF>;
>>>>>>> 	};
>>>>
>