[Letux-kernel] fb tiler considered harmful

Andreas Kemnade andreas at kemnade.info
Wed Feb 15 07:38:29 CET 2017


On Tue, 14 Feb 2017 21:56:47 +0100
"H. Nikolaus Schaller" <hns at goldelico.com> wrote:


> > 
> > 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.
> 
> Indeed.
> 
> I haven't looked for the framebuffer for a while so I didn't notice
> that it is missing completely.
> 
> Well, the splash pictures have a different problem in omapdss that
> they are tried to be initialized before the omapdss has been set up.
> The only solution would be to make everything compiled into the kernel
> instead of loadable modules (which depend a little on the DT, e.g.
> panel drivers).
> 

But everything after the initial udev run can use it, including ordinary
virtual consoles. I even think (have not tested it) the kernel console output
will be readable after that module load if there is no console=ttyO...
in the kernel commandline.

> > 
> >>> 
> >>> 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) {
> 
> yes, looks good. Should be if (omap3()) {
> 
> because I think omap4 and omap5 both have the TILER.
> 
> If you find a patch that makes it work, I can add it.
> 
I have sent a patch. I see sill some warinings after that. But
there is at least a framebuffer.

Regards,
Andreas
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