[RFC PATCH] drm: Add plane event

Marcus Lorentzon marcus.xm.lorentzon at stericsson.com
Wed Apr 18 08:10:47 PDT 2012

On 04/18/2012 04:36 PM, Daniel Vetter wrote:
> Last time around I've discussed with people we've ended up with 2 new
> ioctls:
> - atomic modeset, to configure the output state on more than one crtc at
>    the same time. This is useful to get pll assignement, memory bandwidth
>    constrains and similar stuff right. This ioctl is synchronous. A
>    testmode can be used to inquire the driver whether the proposed mode
>    actually works. This could be used for gui interfaces to automatically
>    grey out unsupportable configurations, e.g. if you have 3 crtc but on 2
>    pll and 2 modes need to have the same pixelclocks to drive all 3 crtcs.
> - an atomic pageflip. This one would be like the current pageflip ioclt,
>    i.e. run asynchronously and deliver a drm event upont completion. The
>    idea is that compositors can use this to make flicker-free compositition
>    with drm planes possible. I think we want drivers to be able to indicate
>    which crtc properties they can switch with this ioctl, e.g. I expect
>    some yuv->rbg color space properties might not work. All the changes
>    should be applied on the same vblank, obviously.
Why an atomic pagefilp? How is this different from an atomic modeset 
where only fbs change? Can't drm frmwrk "optimize" this like SETCRTC 
does today with base/full modeset helpers?


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