[PATCH v6 21/23] drm: rockchip: Add VOP2 driver

[Andy Yan]

Hi Sascha:

On 2/18/22 16:00, Sascha Hauer wrote:
> On Fri, Feb 18, 2022 at 11:50:32AM +0800, Andy Yan wrote:
>> Hi Sascha:
>>
>> On 2/17/22 22:06, Heiko Stübner wrote:
>>> Am Donnerstag, 17. Februar 2022, 14:58:23 CET schrieb Sascha Hauer:
>>>> Hi Andy,
>>>>
>>>> Please trim the context in your answers to the relevant parts, it makes
>>>> it easier to find the things you said.
>>>>
>>>> On Thu, Feb 17, 2022 at 08:00:11PM +0800, Andy Yan wrote:
>>>>> Hi Sascha:
>>>>>
>>>>>> +
>>>>>> +	drm_for_each_encoder_mask(encoder, crtc->dev, crtc_state->encoder_mask) {
>>>>>> +		struct rockchip_encoder *rkencoder = to_rockchip_encoder(encoder);
>>>>>> +		struct device_node *node, *parent;
>>>>>> +
>>>>>> +		parent = of_get_parent(rkencoder->port);
>>>>>> +
>>>>>> +		for_each_endpoint_of_node(parent, node) {
>>>>> Is there any hurt directly use our downstream vendor kernel method here: use
>>>>> vcstate->output_if set by encoder driver to get which interface we should
>>>>> enable here?
>>>> There is no vcstate->output_if in mainline currently. Ok, we could add
>>>> that. The other thing is that there are multiple HDMI interfaces and
>>>> the id of the HDMI encoder is encoded into output_if. Downstream kernel
>>>> adds OF aliases to the HDMI ports. I didn't want to go that route
>>>> because it doesn't seem to be very elegant to me.
>> aliases is a very comm strategy in device tree world.
> Yes, but not for retrieving bit offsets into registers. Normally aliases
> can be changed at board level without confusing drivers.
>
>> And your method also
>> add need additional dt binds to define RK3568_VOP2_EP_xxx
>>>>> You method is ok with device tree,  but it tied up this driver to device
>>>>> tree, we are now tring to extend vop2 driver work with ACPI, so we hope this
>>>>> driver can be much more flexible.
>>>> The current rockchip drm driver seems to be pretty much tied to device
>>>> tree. There are probably many other places that need parallel paths for
>>>> ACPI support, I think we can delay this particular part until we see the
>>>> whole picture. In the end we can still retrieve the output_if
>>>> information differently with ACPI while still retrieving the information
>>>> from the device tree the way we are doing currently.
>> The current driver only reference device thee at driver initial, we not wrap
>>
>> device tree related things in other parts, so if we extend it to support
>> ACPI,
>>
>> we just need modify the initial code, this make things easier.
> The device tree parsing could be moved out of vop2_crtc_atomic_enable()
> into some initialisation path. In the end it's static information,
> there's no need to do it repeatedly in atomic_enable.

This could be one solution, the repeatedly parsing device tree in 
atomic_enable is also my concern.

In addition, there are 2 HDMI, 2 eDP, 2 MIPI on the coming rk3588, so 
it's better to consider give position

for HDMI1, EDP1, in  include/dt-bindings/soc/rockchip,vop2.h

>
> Sascha
>