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

[Stefan Christ]

Hi Daniel,

On Wed, Jul 13, 2016 at 12:00:07PM +0200, Daniel Vetter wrote:
> 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.

Yeah, these closed libraries are kind of ugly, but implementing these features
maybe interesting for legacy framebuffer applications that do double buffering
via panning.

Thanks for the comments. I totally overlooked the dpms/blank and locking issue.
I will work through them and send v2 patches.

Mit freundlichen Grüßen / Kind regards,
	Stefan Christ

> 
> 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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> > https://lists.freedesktop.org/mailman/listinfo/dri-devel
> 
> -- 
> Daniel Vetter
> Software Engineer, Intel Corporation
> http://blog.ffwll.ch