Re: [RFC PATCH 0/3] staging: remove fbdev drivers

From: Daniel Vetter
Date: Thu Dec 08 2016 - 05:10:05 EST

On Thu, Dec 08, 2016 at 12:01:19PM +1100, Benjamin Herrenschmidt wrote:
> On Wed, 2016-11-23 at 10:03 +0200, Tomi Valkeinen wrote:
> > Hi,
> >
> > Since the fbdev framework is in maintenance mode and all new display drivers
> > should be made with the DRM framework, remove the fbdev drivers from staging.
> >
> > Note: the patches are created with git format-patch -D, so they can't be
> > applied. Only for review.
> I missed the discussion where this decision was made, I admit I am
> unimpressed by it.
> DRM drivers don't strike me as suitable for small/slow cores with dumb
> framebuffers or simple 2D only accel, such as the one found in the ASpeed
> BMCs.

We have a helper for simple drivers now, if you take into account the
massive helper libraries for everything that comes along with drm I expect
if even dumb panels behind slow spi buses drm is now the more suitable

> With drmfb you basically have to shadow everything into memory & copy
> over everything, and locks you out of simple 2D accel. For a simple text
> console the result is orders of magnitude slower and memory hungry than
> a simple fbdev.

Not true, we have full fbdev emulation, and drivers can implement the 2d
accel in there. And a bunch of them do. It's just that most teams decided
that this is pointless waste of their time.j

> At least that was the case last I looked at the DRM stuff with Dave,
> maybe things have changed...
> Not everything has a powerful 3D GPU.

That's correct, and drm can cope. And compared to fbdev there's a very
active community who improves&refactors it every kernel release to make it
even better. Since about 2 years (when atomic landed) we merge new drivers at
a rate of 2-3 per kernel release, and those new drivers get ever simpler
and smaller thanks to all this work.
Daniel Vetter
Software Engineer, Intel Corporation