[Letux-kernel] fb tiler considered harmful

Andreas Kemnade andreas at kemnade.info
Tue Feb 14 21:22:34 CET 2017


Hi Nikolaus,

On Tue, 14 Feb 2017 08:51:05 +0100
"H. Nikolaus Schaller" <hns at goldelico.com> wrote:

> Hi Andreas,
> 
> > Am 14.02.2017 um 08:01 schrieb Andreas Kemnade
> > <andreas at kemnade.info>:
> > 
> > Hi,
> > 
> > On Tue, 14 Feb 2017 04:18:16 +0100
> > Matthijs van Duin <matthijsvanduin at gmail.com> wrote:
> > 
> >> Nikolaus, when I tried to merge my rebased patch branches into
> >> letux-4.10-rc8 I got a big mess of merge conflicts because you
> >> merged previous patches from me into it already. Please don't.
> >> 
> >> On 10 February 2017 at 11:37, H. Nikolaus Schaller
> >> <hns at goldelico.com> wrote:
> >> 
> >>> It is easy to remove them completely
> >>> 
> >> 
> >> Please do so from your main letux branch while the patches are
> >> still in development, I'm currently relying on it being a (or
> >> rather the only) known-working kernel for the pyra which I can use
> >> to test my patches.
> >> 
> > +1
> > Well, I generated the branch list from the big merge commit and
> > did a merge myself without that not-ready tiled-fb stuff using the
> > merge script.
> > 
> > But I would favour to be able to just use the letux-4.10-rc8
> > branches directly without having only a white screen after booting.
> 
> Well, in my setup I didn't have a white screen, neither on GTA04 nor
> on Pyra so I never noticed a problem myself... On GTA04 it works for
> me while on Pyra I don't get a rotated screen.
> 
again still the same.

[   59.827239] omapdrm omapdrm.0: DMM not available, disable DMM support
[   59.846588] [drm] Supports vblank timestamp caching Rev 2 (21.10.2013).
[   59.854705] [drm] No driver support for vblank timestamp query.
[   59.863464] omapdrm omapdrm.0: Tiled buffers require DMM
[   59.870483] omapdrm omapdrm.0: failed to allocate buffer object
[   59.878570] omapdrm omapdrm.0: omap_fbdev_init failed
[   59.884979] [drm] Initialized omapdrm 1.0.0 20110917 on minor 0

Now I analyzed a bit further.
There is no framebuffer device like /dev/fb0.
So no blinking cursor appears in the framebuffer and no other stuff
works which relies on it (splash pictures and console on framebuffer)
But what still works is the modesetting xorg driver.

> > 
> > If that is important for some showcase, merge it on top of
> > letux-4.10-rc8 to form a pyra-showcase-4.10-rc8 branch
> > or something like that.
> 
> Well, it should not be a special showcase, it should be possible to
> point pyra and gta04 users to the latest letux kernel w/o making such
> differences. It is the core philosophy of the letux kernel to support
> all devices.
> 
> If there is a bug we should not fix it by workarounds that users can
> see and make them trouble. And pointing people to different kernel
> flavours is not a solution.
> 
> So my main goal is to get the Pyra rotated screen working in 4.10-rc9
> without influencing the GTA04 screen.
> 
> That is what we should work on. Not workarounds for either.
> 
IMHO,
in patch
XXX omapdrm: allocate fbdev in TILER
there has to be a 
if (!pyra) {
...
} else {
+ new stuff
+ ...
}

instead of the
#if 0

...
#else
+ new stuff
+ ...
#endif

Regards,
Andreas
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