Re: [RFC PATCH v1 0/4] Add Rockchip RGA support

From: Yakir Yang
Date: Tue Mar 29 2016 - 07:41:10 EST

Hi Emil,

On 03/28/2016 08:21 PM, Emil Velikov wrote:
On 22 March 2016 at 00:42, Heiko Stuebner <heiko@xxxxxxxxx> wrote:
Hi Yakir,

Am Montag, 21. MÃrz 2016, 20:17:46 schrieb Yakir Yang:
On 03/21/2016 07:29 PM, Heiko StÃbner wrote:
Am Montag, 21. MÃrz 2016, 17:28:38 schrieb Yakir Yang:
This patch set would add the RGA direct rendering based 2d graphics
acceleration module.
very cool to see that.

This patch set is based on git repository below:
git:// drm-next
commit id: 568d7c764ae01f3706085ac8f0d8a8ac7e826bd7

And the RGA driver is based on Exynos G2D driver, it only manages the
command lists received from user, so user should make the command list
to data and registers needed by operation to use.

I have prepared an userspace demo application for testing:

That is a rockchip libdrm library, and I have write a simple test case
"rockchip_rga_test" that would test the below RGA features:
- solid
- copy
- rotation
- flip
- window clip
- dithering
Did you submit your libdrm changes as well?

Userspace-interfaces need to be stable so the other side must also get
accepted - even before the kernel change if I remember correctly.
Got it, and I just saw exynos_fimg2d already landed at mainline libdrm.
But I don't find the way to submit patches to libdrm, would you like
share some helps here ;)
Looking at the libdrm sources on, I did not find any
specific manual on submitting patches.

But looking at the dri-list archive, dri-devel@xxxxxxxxxxxxxxxxxxxxx is the
right list and looking at the libdrm history it looks like Emil Velikov
<emil.l.velikov@xxxxxxxxx> seems to be doing maintenance-stuff in libdrm.
And as a 3rd recipient, please also include the linux-rockchip list.

@Emil, please shout if I read that wrong :-)

You got it spot on Heiko. There are a few notes though...

As one reuses the existing hardware/IP block, it would be better to
avoid copy/pasting code around.
- (if possible) factor out the exynos g2d kernel functionality to a
separate kernel module and wire up the rockhip (via dt ?) to use it
- factor out the g2d specifics out of exynos_drm.h (into
exynos_g2d_drm.h perhaps ?) and make sure exynos_drm.h includes the
new header
- if neither of these are possible, then please ensure that the new
header uses correct types (see the docs [1]), use MIT/X11 license (if
possible) and link where upstream userspace is happy with the
interface (ideally more than a simple test app like libdrm)

Whops... you have provided the third choice, nice :-D

And I got little idea about license, where should I use the MIT/X11
license, should I declare the MIT/X11 license in kernel uapi head
file, but Andreas just remind that kernel do not allow to no GUN
license. Or may be I can:
1. Use GUN license in kernel rockchip_drm.h uapi head file
2. Use MIT/X11 license in libdrm rockchip_drm.h head file.

And I don't understand the "link where upstream userspace is happy
with the interface", could you reference small example here.

- Yakir

These might sound like an overkill, although getting UAPI right and
maintaining it forever forces us to do so.