[PATCH 0/3] Support fast framebuffer panning for i.MX6

[Daniel Vetter]

On Wed, Jul 13, 2016 at 10:11:45AM +0200, Stefan Christ wrote:
> Hi,
> 
> im currently working on supporting double/tripple buffering for the framebuffer
> emulation on the i.MX6.  While working on it I noticed that the mainline kernel
> does not support some features in the generic drm framebuffer emulation for
> framebuffer panning and vsync synchronisation. They are needed for simple
> framebuffer applications and some OpenGL libraries using double buffering with
> FBIOPUT_VSCREENINFO, FBIO_WAITFORVSYNC and FBIOPAN_DISPLAY.
> 
> Any comments?

Don't ever do OpenGL on fbdev. Ever. The fbdev emulation we have is to
support boot splashs, kernel console, oopses and legacy applications that
just love fbdev too much and don't support native kms dumb buffers.

Anything that goes beyond kms dumb buffers (like displaying buffers
rendered through opengl) is imo a complete no-go. Yes Android loves to do
that, but for upstream we need a proper drm render driver, buffer sharing
through prime and the userspace hwcomposer needs to use native drm kms
ioctls. Also, userspace (especially the opengl part) needs to be open
source for upstream.

Thanks, Daniel
> 
> Kind regards,
> 	Stefan Christ
> 
> Stefan Christ (2):
>   drm: fb_helper: implement ioctl FBIO_WAITFORVSYNC
>   drm/imx: ipuv3-crtc: implement fast path mode_set_base
> 
> Xinliang Liu (1):
>   drm/cma-helper: Add multi buffer support for cma fbdev
> 
>  drivers/gpu/drm/Kconfig             |  8 +++++++
>  drivers/gpu/drm/drm_fb_cma_helper.c |  9 +++++++-
>  drivers/gpu/drm/drm_fb_helper.c     | 43 +++++++++++++++++++++++++++++++++++++
>  drivers/gpu/drm/imx/ipuv3-crtc.c    | 10 +++++++++
>  include/drm/drm_fb_helper.h         |  2 ++
>  5 files changed, 71 insertions(+), 1 deletion(-)
> 
> -- 
> 1.9.1
> 
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-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch