On Thu, Jul 28, 2016 at 11:01:04AM +0800, Mark yao wrote:
Any ideas for the share planes?
This function is important for our series of vop full design. The series of vop is: IP version chipname 3.1 rk3288 3.2 rk3368 3.4 rk3366 3.5 rk3399 big 3.6 rk3399 lit 3.7 rk322x
example on rk3288: if not support share plane, each vop only support four planes, but if support this function, each vop can support ten planes.
Like I said, register 10 planes in the kernel driver, figure out a good way to actually allocate them to hw resources. We have a similar issue on skl/bxt in the i915 driver where there's only a limited amount of scalers, and we need to dynamically allocate them to drm_plane. Here you have fancy amount of scanout engines which you need to dynamically allocate.
On 2016年07月26日 17:51, Mark yao wrote:
On 2016年07月26日 16:26, Daniel Vetter wrote:
On Tue, Jul 26, 2016 at 03:46:32PM +0800, Mark Yao wrote:
What is share plane: Plane hardware only be used when the display scanout run into
plane active
scanout, that means we can reuse the plane hardware resources on plane non-active scanout.
-------------------------------------------------- | scanout | | ------------------ | | | parent plane | | | | active scanout | | | | | ----------------- | | ------------------ | share plane 1 | | | ----------------- |active scanout | | | | share plane 0 | | | | | |active scanout | ----------------- | | | | | | ----------------- | --------------------------------------------------One plane hardware can be reuse for multi-planes, we assume the first plane is parent plane, other planes share the resource with first one. parent plane |---share plane 0 |---share plane 1 ...
Because resource share, There are some limit on share plane: one group of share planes need use same zpos, can not overlap, etc.
We assume share plane is a universal plane with some limit flags. people who use the share plane need know the limit, should call
the ioctl
DRM_CLIENT_CAP_SHARE_PLANES, and judge the planes limit before use it.
A group of share planes would has same shard id, so userspace can group them, judge share plane's limit.
Signed-off-by: Mark Yaomark.yao@rock-chips.com
This seems extremely hw specific, why exactly do we need to add a new relationship on planes? What does this buy on_other_ drivers?
Yes, now it's plane hardware specific, maybe others have same design, because this design would save hardware resource to support multi-planes.
Imo this should be solved by virtualizing planes in the driver. Start out by assigning planes, and if you can reuse one for sharing then do that, otherwise allocate a new one. If there's not enough real planes, fail the atomic_check.
I think that is too complex, trying with atomic_check I think it's not a good idea, userspace try planes every commit would be a heavy work.
Userspace need know all planes relationship, group them, some display windows can put together, some can't, too many permutation and combination, I think can't just commit with try.
example: userspace: windows 1: pos(0, 0) size(1024, 100) windows 2: pos(0, 50) size(400, 500) windows 3: pos(0, 200) size(800, 300)
drm plane resources: plane 0 and plane 1 is a group of share planes plane 2 is common plane.
if userspace know the relationship, then they can assign windows 1 and window 3 to plane0 and plane 1. that would be success. but if they don't know, assign window 1/2 to plane 0/1, failed, assign window 2/3 to plane 0/1, failed. mostly would get failed.
You can still do this with the design I describe. The only difference is that you allow generic userspace to make optimal use of your planes, too.
This seems way to hw specific to be useful as a generic concept.
We want to change the drm_mode_getplane_res behavior, if userspace call DRM_CLIENT_CAP_SHARE_PLANES, that means userspace know hardware limit, then we return full planes support to userspace, if don't, just make a group of share planes as one plane. this work is on generic place.
So ... do you have patches for all the generic kms userspace that's out there? Are those reviewed and ready for merging?
Adding new userspace abi is much, much, much harder than sovling this in the vop driver. I'm working on some documentation to make this all clear (since many arm folks seem unaware of the uapi rules we have in the drm subsystem). But really, you're trying the much harder route with this patch. -Daniel