[PATCH 0/3] drm/exynos: add support for dynamic zpos in DECON and FIMD

[Andrzej Hajda]

On 11.12.2018 09:01, Inki Dae wrote:
>
> 18. 12. 11. 오후 4:49에 Andrzej Hajda 이(가) 쓴 글:
>> On 11.12.2018 00:45, Inki Dae wrote:
>>> Hi Andrzej,
>>>
>>> 18. 12. 10. 오후 4:35에 Andrzej Hajda 이(가) 쓴 글:
>>>> Hi Inki,
>>>>
>>>> On 10.12.2018 03:25, Inki Dae wrote:
>>>>> Hi Andrzej,
>>>>>
>>>>> 18. 12. 6. 오후 6:38에 Andrzej Hajda 이(가) 쓴 글:
>>>>>> Hi Inki,
>>>>>>
>>>>>> This small patchset adds dynamic zpos support for DECON and FIMD.
>>>>> This patch will allow user space to change zpos. However, DECON and FIMD devices have fixed priority of HW overlays.
>>>>> This would mean that zpos change by user space doesn't guarantee correct HW overlay priority.
>>>>>
>>>>> Why do you want to support mutable zpos?
>>>> Practically you have patches which proves it works, you can see that
>>>> changing zpos value results in adequate change in displayed image.
>>>>
>>>> Conceptually it is just a matter of disconnecting hardware windows
>>>> present in DECON and FIMD from DRM planes which are software entities.
>>>>
>>>> You can reason about it this way:
>>>>
>>>> - drm plane is a framebuffer plus informations how it should be
>>>> transformed/displayed on DECON/FIMD,
>>>>
>>>> - hw window in DECON/FIMD is just a channel through which plane is send
>>>> to the display.
>>>>
>>>> DECON and FIMD has fixed hw windows order - windows with lower numbers
>>>> are displayed below windows with higher number. To display planes in
>>>> given z-order you just need to send them via windows with appropriate
>>>> index - farthest plane should go always via win0, closer one via win1,
>>>> ..., till the last plane.
>>>>
>>>> So for example if you have three planes and want to display them in
>>>> following order (first one farthest, last one closest):
>>>>
>>>> plane2, plane1, plane3
>>>>
>>>> you should map them to planes as follow:
>>>>
>>>> plane2 -> win0, plane1 -> win1, plane3 -> win2
>>>>
>>>> then for example plane2 is disabled, we will have following mapping:
>>>>
>>>> plane1 -> win0, plane3 -> win1, win2 - disabled
>>> Plane1 is displayed below Plane3.
>>
>> And this is what we wanted, the initial order was: plane2, plane1,
>> plane3, first farthest (or lowest if you prefer this naming schema).
>>
>>
>>>> then if you change zorder of planes to: plane3, plane1:
>>>>
>>>> plane3 -> win0, plane1 -> win1
>>> Plane3 is displayed below Plane1 because DECON/FIMD HW aren't able to change HW overlay priroty.
>>
>> No, plane3 is displayed below plane1 because we sent it via win0, if we
>> want inverse we can send plane3 via win1 and plane1 via win0.
>>
>>
>>> However, user space wanted that Plane1 is displayed below Plane3. Like this, zpos change by user space doesn't guarantee correct HW overlay priority.
>>
>> As I said before in this example userspace wanted plane3 below plane1,
>> and as I wrote in comment above any order of planes user want driver is
>> able to realize with this patch.
>>
>>
>>> And there is no any reason to change zpos in user space excepting Mixer device which supports HW overlay priority change.
>>
>> Lack of special registry for manipulating windows order does not mean it
>> cannot support dynamic zpos.
>>
> Why changing zpos in user space is required?
>
>>> In fact, we supported mutable zpos before but changed it to immutable with same reason.
>>
>> It was just broken if I remember correctly.
>>
> No, I worked well and real user used it I remember.
>
>>> Lastly, your patch made real user broken.
>>
>> Who? How?
> Window server of Tizen didn't work and you can test it with below image - I didn't check why it doesn't. Anyway, we don't have to break real user.
> http://download.tizen.org/snapshots/tizen/unified/latest/images/standard/mobile-wayland-armv7l-tm2/


Are you saying it works with latest mainline without my patches?


Regards

Andrzej


>
> Thanks,
> Inki Dae
>
>>
>> Regards
>>
>> Andrzej
>>
>>
>>> Thanks,
>>> Inki Dae
>>>
>>>> As you see there is no relation between plane number and window number,
>>>> but window number is equal to plane's position in zpos-ordered list of
>>>> planes and this is exact value of normalized_zpos field in drm_plane_state.
>>>>
>>>>
>>>> I hope this extended explanation will clarify things.
>>>>
>>>>
>>>> Regards
>>>>
>>>> Andrzej
>>>>
>>>>
>>>>
>>>>> Thanks,
>>>>> Inki Dae
>>>>>
>>>>>> It was tested on tm2 and trats2.
>>>>>>
>>>>>> Regards
>>>>>> Andrzej
>>>>>>
>>>>>>
>>>>>> Andrzej Hajda (3):
>>>>>>   drm/exynos/decon5433: add dynamic zpos support
>>>>>>   drm/exynos/fimd: create local helper for disabling hardware window
>>>>>>   drm/exynos/fimd: add dynamic zpos support
>>>>>>
>>>>>>  drivers/gpu/drm/exynos/exynos5433_drm_decon.c | 23 +++++-----
>>>>>>  drivers/gpu/drm/exynos/exynos_drm_fimd.c      | 42 ++++++++-----------
>>>>>>  2 files changed, 29 insertions(+), 36 deletions(-)
>>>>>>
>>>>
>>
>>
>