Re: [PATCH v5 0/5] Add ARM Mali Midgard device tree bindings and gpu node for rk3288

[Guillaume Tucker]

Hi Randi,

On 09/05/17 08:45, Randy Li wrote:
> On 05/09/2017 03:40 PM, Guillaume Tucker wrote:
> > On 09/05/17 02:16, Randy Li wrote:
> > > On 05/09/2017 12:27 AM, Heiko StÃbner wrote:
> > > > Am Mittwoch, 3. Mai 2017, 10:56:24 CEST schrieb Guillaume Tucker:
> > > > > The ARM Mali Midgard GPU kernel driver is only available
> > > > > out-of-tree and is not going to be merged in its current form.
> > > > > However, it would be useful to have its device tree bindings
> > > > > merged.  In particular, this would enable distributions to create
> > > > > working driver packages (dkms...) without having to patch the
> > > > > kernel.
> > > > >
> > > > > The bindings for the earlier Mali Utgard GPU family have already
> > > > > been merged, so this is essentially the same scenario but for
> > > > > newer GPUs (Mali-T604 ~ Mali-T880).
> > > > >
> > > > > This series of patches first imports the bindings from the latest
> > > > > driver release with some clean-up then adds a gpu node for the
> > > > > rk3288 SoC.  This was successfully tested on Radxa Rock2 Square,
> > > > > Firefly, Veyron Minnie and Jerry boards using Mali kernel driver
> > > > > r16p0 and r12p0 user-space binary.
> > > I won't suggest such combine. We meet some problems at mali 400 serial.
> > > I would suggest the kernel version would match the user library.
> >
> > Well, I can test it again with r12p0 kernel driver (out-of-tree)
> > if you want.  The user-space driver checks the version of the
> > kernel driver and gives up if it's not compatible.  With Midgard,
> > there's a range of versions that maintain kernel/userspace
> > compatibility unlike Utgard and older Midgard releases where they
> > had to exactly match.  Again, if there was a mismatch then the
> > user-space would fail to initialise and report an error.

> Anyway, could you verify the mali userspace library r13p0?

The latest user-space binary available from developer.arm.com for
rk3288 is 12p0.  Maybe Rockchip could make some new binaries
available to the public?

> Rockchip would use this version to offer the support of X11, wayland and gbm.

Sounds great, although windowing systems are quite far away from
GPU device tree bindings so I don't think this is too relevant
for this current patch series.

On a side note, it would be fantastic to get all this available
in Debian packages :)

> > > Also please notice there is rk3288w, the hardware version becomes r1p0.
> >
> > Sounds like a new SoC?  Does rk3288w affect rk3288 in any way?
> It is not a new SoC, just a new version of rk3288. It fixes a various of the chip bug of the rk3288.

I see.  I don't have access to any rk3288w platform but if you do
then I guess it would be nice if you could test these patches on
it :)  Also I'm not sure if all rk3288 device trees changes must
be tested on rk3288w, and this SoC is not mentioned anywhere in
the kernel (as far as I can tell).

Is there anything you think should block these current patches
which only claim to support rk3288 from being merged?

> > Unless it's a special case, it seems to me that any new SoC with
> > a Midgard GPU would need an extra vendor compatible string in the
> > binding documentation and maybe a separate gpu dt node.
> >
> > > > The actual devicetree parts are all Rockchip-specific, so I guess I'll just
> > > > pick up the whole series, including the binding doc, after the merge
> > > > window if nobody complains before that :-)
> >
> > Thanks!

Guillaume


P.S. kernel branch with a Mali driver I used for testing:
https://git.collabora.com/cgit/user/gtucker/linux.git/log/?h=linux-4.11-mali-dt-rk3288