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

From: Daniel Vetter <daniel@ffwll.ch>
To: Stefan Christ <s.christ@phytec.de>
Cc: dri-devel@lists.freedesktop.org
Subject: Re: [PATCH 0/3] Support fast framebuffer panning for i.MX6
Date: Fri, 15 Jul 2016 09:14:56 +0200	[thread overview]
Message-ID: <20160715071456.GL17101@phenom.ffwll.local> (raw)
In-Reply-To: <20160714151138.GA3428@lws-christ>

On Thu, Jul 14, 2016 at 05:11:38PM +0200, Stefan Christ wrote:
> 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.

In case it wasn't obvious: Don't sell this with "makes blob opengl drivers
work". Find some old userspace that uses raw fbdev, sell this patch series
using that one ;-)
-Daniel

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

-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
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