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Re: No more new fbdev drivers, please

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Hi

On Sat, Sep 26, 2015 at 8:01 PM, Geert Uytterhoeven
<geert@linux-m68k.org> wrote:
> Hi Alex,
>
> On Sat, Sep 26, 2015 at 7:07 PM, Alex Deucher <alexdeucher@gmail.com> wrote:
>> On Sat, Sep 26, 2015 at 4:28 AM, Geert Uytterhoeven
>> <geert@linux-m68k.org> wrote:
>>> On Thu, Sep 24, 2015 at 5:23 PM, Daniel Vetter <daniel@ffwll.ch> wrote:
>>>> On Thu, Sep 24, 2015 at 02:46:21PM +0200, Thomas Petazzoni wrote:
>>>>> Or are there some plans to make the writing of DRM drivers for very
>>>>> simple/trivial devices a bit simpler?
>>>>
>>>> Since years I'm trying to sell someone on implementing support for
>>>> drm_simple_outputs which would collapse the crtc->encoder->connector
>>>> chain into 1 entity. Would be trivial to implement and then trivial to
>>>> write simple drivers on top of that. And besides that drm already has
>>>> piles of reallly simple drivers with just one output and one framebuffer.
>>>>
>>>> There's no reason not to use drm for gfx drivers at all.
>>>
>>> Good to hear that!
>>>
>>> For the (mailing list) record, can you please provide some explicit pointers
>>> to these existing really simple drivers?
>>
>> See the tilcdc, ast, mgag200, and udl drivers for example.
>
> Thanks for the list!
>
> The smallest of these (udl) still counts in at ca. 2800 LoC, while there are
> several fbdev drivers that have less than 200 LoC.
> Granted, these really small ones support a single fixed video mode only, but
> you can write a simple fbdev driver with mode setting in less than 1000 LoC.
>
> I'm sure DRM can do better?

Is counting lines really the level of the discussion to go here?

DRM is a big set of helpers, nothing else. If many trivial, small
drivers share common code, developers are more than welcome to
contribute them to drm-core and help making drivers less complex.

As Daniel mentioned, the connector+encoder+crtc combination is one of
those simplifications that would make sense if more such drivers are
added. Furthermore, the not-yet-merged SimpleDRM driver is one example
how to implement multiple of those dumb-fb drivers with a shared
code-base.

Thanks
David
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Thread

No more new fbdev drivers, please Tomi Valkeinen <tomi.valkeinen@ti.com> - 2015-09-24 14:30 +0200
  Re: No more new fbdev drivers, please Thomas Petazzoni <thomas.petazzoni@free-electrons.com> - 2015-09-24 14:50 +0200
    Re: No more new fbdev drivers, please Austin S Hemmelgarn <ahferroin7@gmail.com> - 2015-09-24 17:30 +0200
      Re: No more new fbdev drivers, please Alex Deucher <alexdeucher@gmail.com> - 2015-09-24 17:40 +0200
      Re: No more new fbdev drivers, please Daniel Vetter <daniel@ffwll.ch> - 2015-09-24 18:00 +0200
        Re: No more new fbdev drivers, please Austin S Hemmelgarn <ahferroin7@gmail.com> - 2015-09-24 18:20 +0200
        Re: No more new fbdev drivers, please Ondrej Zary <linux@rainbow-software.org> - 2015-09-24 19:20 +0200
          Re: No more new fbdev drivers, please Daniel Vetter <daniel@ffwll.ch> - 2015-09-24 20:10 +0200
    Re: No more new fbdev drivers, please Daniel Vetter <daniel@ffwll.ch> - 2015-09-24 17:30 +0200
      Re: No more new fbdev drivers, please Geert Uytterhoeven <geert@linux-m68k.org> - 2015-09-26 10:30 +0200
        Re: No more new fbdev drivers, please Alex Deucher <alexdeucher@gmail.com> - 2015-09-26 19:10 +0200
          Re: No more new fbdev drivers, please Geert Uytterhoeven <geert@linux-m68k.org> - 2015-09-26 20:10 +0200
            Re: No more new fbdev drivers, please David Herrmann <dh.herrmann@gmail.com> - 2015-09-26 20:20 +0200
              Re: No more new fbdev drivers, please Geert Uytterhoeven <geert@linux-m68k.org> - 2015-09-26 20:50 +0200
                Re: No more new fbdev drivers, please Rob Clark <robdclark@gmail.com> - 2015-09-26 22:50 +0200
                Re: No more new fbdev drivers, please Dave Airlie <airlied@gmail.com> - 2015-09-27 00:00 +0200
                Re: No more new fbdev drivers, please Emil Velikov <emil.l.velikov@gmail.com> - 2015-09-30 14:00 +0200
              Re: No more new fbdev drivers, please Gerd Hoffmann <kraxel@redhat.com> - 2015-09-28 09:50 +0200
                Re: No more new fbdev drivers, please Daniel Vetter <daniel@ffwll.ch> - 2015-09-28 14:40 +0200
                Re: No more new fbdev drivers, please Gerd Hoffmann <kraxel@redhat.com> - 2015-09-29 10:30 +0200
                Re: No more new fbdev drivers, please Laurent Pinchart <laurent.pinchart@ideasonboard.com> - 2015-09-29 10:40 +0200
            Re: No more new fbdev drivers, please Bernie Thompson <bernie@plugable.com> - 2015-09-28 23:00 +0200
            Re: No more new fbdev drivers, please Daniel Vetter <daniel@ffwll.ch> - 2015-09-29 09:10 +0200
  Re: No more new fbdev drivers, please Aaro Koskinen <aaro.koskinen@iki.fi> - 2015-09-25 11:00 +0200
    Re: No more new fbdev drivers, please Ondrej Zary <linux@rainbow-software.org> - 2015-09-25 13:10 +0200
  Re: No more new fbdev drivers, please Sudip Mukherjee <sudipm.mukherjee@gmail.com> - 2015-09-26 09:20 +0200
    Re: No more new fbdev drivers, please Ilia Mirkin <imirkin@alum.mit.edu> - 2015-09-26 09:40 +0200
  Re: No more new fbdev drivers, please Noralf Trønnes <noralf@tronnes.org> - 2015-09-27 15:20 +0200
    Re: No more new fbdev drivers, please Emil Velikov <emil.l.velikov@gmail.com> - 2015-09-27 18:10 +0200
      Re: No more new fbdev drivers, please Noralf Trønnes <noralf@tronnes.org> - 2015-09-29 01:00 +0200
        Re: No more new fbdev drivers, please Daniel Vetter <daniel@ffwll.ch> - 2015-09-29 09:10 +0200

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