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

[Yakir Yang]

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://people.freedesktop.org/~airlied/linux 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:
> > > > >     https://github.com/yakir-Yang/libdrm-rockchip
> > > > >
> > > > > 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 cgit.freedesktop.org, 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.
> Namely:
>   - (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.

Thanks,
- Yakir

> These might sound like an overkill, although getting UAPI right and
> maintaining it forever forces us to do so.
>
> Regards,
> Emil
>
> [1] https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/ioctl/botching-up-ioctls.txt