How to support various hardware blocks in drm driver

[Rob Clark]

On Tue, Mar 18, 2014 at 8:58 AM, Inki Dae <inki.dae at samsung.com> wrote:
> 2014-03-18 21:47 GMT+09:00 Daniel Vetter <daniel at ffwll.ch>:
>> On Tue, Mar 18, 2014 at 1:42 PM, Inki Dae <inki.dae at samsung.com> wrote:
>>> I think now drm_bridge couldn't do what we want for embedded systems
>>> as long as drm_encoder has drm_bridge.
>>> See the blow hardware pipeline,
>>> Display Controller-----Image Enhancement chip-----MIP DSI-----MIPI TO
>>> LVDS Bridge-----LCD Panel
>>>
>>> In above hardware pipeline, Display controller is controlled by crtc,
>>> and Image Enhancement chip receives output from display controller.
>>> So the use of existing drm_bridge would be suitable to only bridge
>>> devices between MIPI DSI and LCD Panel, but not to Image Enhancement
>>> chip.
>>>
>>> For such hardware, drm_panel infrastructure is more reasonable to me,
>>> and that is why I try to integrate drm_panel and drm_bridge to one
>>> integrated framework which has infrastructure same as existing
>>> drm_panel.
>>> The important thing is to free this integrated framework from
>>> drm_encoder so that crtc device can also use this framework.
>>
>> Hm, what is this image enhancement chip? Is that some IP block on the
>> SoC? Is it optional? Can it be attached to different crtcs?
>
> In case of Exynos, this chip is in SoC, and can be only attached to
> one crtc, display controller. But I'm not sure other SoC have similar
> chip.
>
>>
>> I think we have similar things on intel hardware, but without details
>> on what it does and how it works I can't really say how to best expose
>> it to userspace and how to best handle it internally in the driver.
>> -Daniel
>
> Simply saying, the image enhancement chip can enhance image data from
> display controller, i.e. saturation enhancement, color reproduction,
> dithering, and so on.
> And this chip receives image data through hardware wired lines
> connected internally between display controller and this chip.

I suppose in some sense it doesn't really matter if it is internal
block or external chip..

but I'm still a bit confused about why you think drm_panel is a better
fit.. could you explain that part?

BR,
-R

> Thanks,
> Inki Dae
>
>> --
>> Daniel Vetter
>> Software Engineer, Intel Corporation
>> +41 (0) 79 365 57 48 - http://blog.ffwll.ch
>> _______________________________________________
>> dri-devel mailing list
>> dri-devel at lists.freedesktop.org
>> http://lists.freedesktop.org/mailman/listinfo/dri-devel
> _______________________________________________
> dri-devel mailing list
> dri-devel at lists.freedesktop.org
> http://lists.freedesktop.org/mailman/listinfo/dri-devel