Re: [PATCH] fbdev: Remove udlfb driver

[Thomas Zimmermann <tzimmermann@suse.de>]

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Hi

Am 30.11.20 um 15:31 schrieb Mikulas Patocka:
> 
> 
> On Mon, 30 Nov 2020, Thomas Zimmermann wrote:
> 
>> Udlfb has been superseded by DRM's udl. The DRM driver is better by
>> any means and actively maintained. Remove udlfb.
> 
> Hi
> 
> I am using udlfb and it's definitely better than the DRM driver. The DRM
> driver will crash the kernel if you unplug the device while Xorg is
> running. The framebuffer driver doesn't crash in this case. (I have a cat
> and the cat sometimes unplugs cables and I don't want to reboot the system
> because of it :-)

What's the exact STR here? Just open the /dev/fb* and pull the cable.

Do I need a cat? :)

> The framebuffer driver is faster, it keeps back buffer and updates only
> data that differ between the front and back buffer. The DRM driver doesn't
> have such optimization, it will update everything in a given rectangle -
> this increases USB traffic and makes video playback more jerky.

That's not quite true, but not false either. I think we could optimize 
what we have.

> 
> The framebuffer driver supports programs running full-screen directly on
> the framebuffer console, such as web browser "links -g", image viewer
> "fbi", postscript+pdf viewer "fbgs", ZX Spectrum emulator "fuse-sdl",
> movie player "mplayer -vo fbdev". The DRM driver doesn't run them.

I would expect that most programs have an SDL2 backend. (?) IIRC SDL2 
has support for DRI interfaces.

> 
> If you seach for someone to maintain the framebuffer driver, I can do it.

I'm looking for reasons why udlfb is still around. What I got from this 
thread is the possible crash and a lack of DRM's fbdev performance. 
Thanks for the feedback.

Best regards
Thomas

> 
> Mikulas
> 
> 
>> Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
>> ---
>>   CREDITS                      |    5 +
>>   Documentation/fb/index.rst   |    1 -
>>   Documentation/fb/udlfb.rst   |  162 ---
>>   MAINTAINERS                  |    9 -
>>   drivers/video/fbdev/Kconfig  |   17 +-
>>   drivers/video/fbdev/Makefile |    1 -
>>   drivers/video/fbdev/udlfb.c  | 1994 ----------------------------------
>>   7 files changed, 6 insertions(+), 2183 deletions(-)
>>   delete mode 100644 Documentation/fb/udlfb.rst
>>   delete mode 100644 drivers/video/fbdev/udlfb.c
> 

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer


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