[PATCH 5/5] drm/exynos: Add plane support with fimd

[Rob Clark]

On Mon, Dec 12, 2011 at 8:39 PM, Inki Dae <inki.dae at samsung.com> wrote:
> Hi, Rob.
> below is my answer.
>
>> -----Original Message-----
>> From: Rob Clark [mailto:robdclark at gmail.com]
>> Sent: Tuesday, December 13, 2011 9:48 AM
>> To: Joonyoung Shim
>> Cc: Inki Dae; kyungmin.park at samsung.com; sw0312.kim at samsung.com; dri-
>> devel at lists.freedesktop.org
>> Subject: Re: [PATCH 5/5] drm/exynos: Add plane support with fimd
>>
>> On Mon, Dec 12, 2011 at 6:41 PM, Joonyoung Shim <jy0922.shim at samsung.com>
>> wrote:
>> > On 12/13/2011 06:59 AM, Rob Clark wrote:
>> >>
>> >> On Fri, Dec 9, 2011 at 4:59 AM, Inki Dae<inki.dae at samsung.com>  wrote:
>> >>>
>> >>> From: Joonyoung Shim<jy0922.shim at samsung.com>
>> >>>
>> >>> The exynos fimd supports 5 window overlays. Only one window overlay of
>> >>> fimd is used by the crtc, so we need plane feature to use the rest
>> >>> window overlays.
>> >>>
>> >>> This creates one ioctl exynos specific - DRM_EXYNOS_PLANE_SET_ZPOS, it
>> >>> is the ioctl to decide for user to assign which window overlay.
>> >>>
>> >> btw, I think I will end up with a similar ioctl.. so thought I'd
>> >> double check for consistency, is zorder interpreted from back to front
>> >> or front to back?  Ie. higher numeric value in front or behind of
>> >> lower numeric value?  Are negative values permitted?
>> >
>> >
>> > The zpos of exynos plane is just the index of overlay of exynos fimd or
>> > exynos hdmi. 0 zpos means first overlay and 1 zpos means second overlay.
>> > It isn't the priority value but higher zpos will have higher priority
>> > generally.
>>
>> I'm not sure that I quite understand that.. does that mean zpos=1 will
>> be in front of zpos=0 (which would be in front of crtc, aka zpos=-1).
>> Do you have a way to put overlays *behind* crtc layer (which
>> presumably would be in some mode with an alpha channel?)
>>
>> (IIRC, samsung has some public TRM type document.. if this is covered
>> there, feel free to answer by just pointing me at the section I should
>> read)
>>
>
> I know that omap, at least omap3(Display Controller of the Display
> Subsystem), has two modes. one is normal mode and another is alpha mode. and
> they also have different overlay priority but Samsung exynos has fixed
> priority to hardware overlays. so higher overlay always is in front of lower
> overlay. in case of plane module for Samsung SoC, if zpos is -1 then crtc
> has default overlay designated by machine code. so whether some overlay is
> in front of crtc or not would be decided by default overlay.

ahh, ok..  I was hoping it was as easy as omap4 where we can just set
arbitrary z-order (0-4) for any of the layers (crtc or overlay).  So
maybe not a way to completely abstract this in the same way for
userspace (but the case is the same in omap3 where it is either normal
or alpha mode.. and I hadn't really decided yet how to handle the
difference between omap generations for this sort of API yet).

I guess userspace ddx driver (or wayland compositor, etc) would still
need to know a bit about what is under the hood.. sigh..

BR,
-R


> Thank you,
> Inki Dae.
>
>
>> BR,
>> -R
>>
>> > A negative value -1 is defined to special value. A exynos crtc should
>> > use one overlay and -1 zpos means the overlay that crtc uses.
>> >
>> > Thanks.
>> >
>> >> BR,
>> >> -R
>> >>
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>> >>
>> >
>