[QUESTION] drm/meson: Hardware cursor plane for Amlogic/meson

[Neil Armstrong]

Hi,

On 15/08/2020 10:59, Martin Blumenstingl wrote:
> Hello Jian-Hong Pan,
> 
> On Wed, Aug 5, 2020 at 9:54 AM Jian-Hong Pan <jian-hong at endlessm.com> wrote:
> [...]
>> We also learned there is the hardware cursor plane supported by
>> Amlogic chips from the slide "Mainline Linux on AmLogic SoCs" [3]. Is
>> it possible to have the hardware cursor available over the drm
>> interface?
> as far as I understand it is technically possible but currently not implemented.
> We have a specific TODO item for this, see [0]
> 
> also I'm not sure if this is trivial to implement and whether there
> are any plans to do so

Sorry I was on vacation !

Yes it's technically possible, but not trivial.

The blocking point is Interlaced support, currently we use the single available
scaler to automatically switch the field on each vsync on the primary plane.

But if we were using a secondary plane for cursor, we would need to switch the field
manually for this plane.

Clearly it's not an issue, but the plane management has changed for G12A and support for
this would need to be added at the same time.

We (BayLibre) do not plan to implement it in the short or long term, but it's clearly a wanted feature.

Neil

> 
> 
> Best regards,
> Martin
> 
> 
> [0] http://linux-meson.com/doku.php#todo
> 
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