How to support various hardware blocks in drm driver

[Inki Dae]

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.

Thanks,
Inki Dae

> --
> Daniel Vetter
> Software Engineer, Intel Corporation
> +41 (0) 79 365 57 48 - http://blog.ffwll.ch
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