Actually adding David. -Daniel On Fri, Jul 29, 2016 at 10:20:51AM +0200, Daniel Vetter wrote: > On Thu, Jul 28, 2016 at 04:15:04PM +0200, Noralf Trønnes wrote: > > This patchset explores the idea of adding a DRM text mode > > (like VGA text mode) to get an alternative to fbcon/fbdev. > > > > David Hermann has done alot of work on a fbcon replacement: > > - drm: add kernel-log renderer (Mar 2014)[1] > > - kmscon: > > development started Nov 2011 > > added to systemd Oct 2014 > > removed from systemd Jul 2015[2] > > > > Since this work seems to have stalled, I propose an alternative solution > > to this problem that will also give VT console support while we're waiting > > for a userspace console. > > > > The idea is that the driver provides a modeset like with the fbdev emulation > > code, and from this a text buffer representation is made. The console code > > can now write to this text buffer and ask for the text buffer to be > > flushed/rendered to the pixel buffer. > > > > In this hack/implementation of the idea, I have just hijacked a CMA backed > > fbdev framebuffer to keep it simple. > > I have reused the default buffer format that VT uses. > > Getting panic handling to actually work, seems to be a challenge as Daniel > > describes on the DRMJanitors page[3]. > > > > Is this idea of a DRM text mode worth developing further? > > I guess some simpler drm console with vt support which would allow us to > get rid of fbdev could make sense. And there's definitely going to be a > lot of overlap with a full userspace solution using something like kmscon. > > But we can't just add a new drm text console, there's a pile of prep work > needed that David started for either approach: > - Nuking fbdev means no more fbdev drivers for firmware consoles (uboot, > uefi, vga, ...). The simpledrm driver would cover this, would be great > to get that landed (especially now that we have the simple pipe > helpers!). > > - One nice benefit of fbdev is that it automatically gets rid of these > firmware-based display drivers when the real driver loads. Some drivers > do this properly even when fbdev isn't enabled (see i915_kick_out_vgacon > and i915_kick_out_firmware_fb), but pretty much all others fail in some > way or the other. David also had some code (iirc as part of simpledrm) > to solve this issue. > > - I think we need more than rbg565 render support, iirc David also had > some work in that area. > > - None of these approaches has a good answer yet to the configuration > question. For a full VT I think we definitely should share the setup > logic with the fbdev emulation code to make it useful, but as describe > in the DRMJanitors page handlings panics is an entierly different > problem. > > Definitely coordinate with David Herrmann here too, since if we do > something in this area it should be widely supported. > > Aside: Where's the pull request for your driver? ;-) > > Cheers, Daniel > > > > > > > Noralf. > > > > [1] https://lwn.net/Articles/589858/ > > [2] https://github.com/systemd/systemd/pull/747 > > [3] https://www.x.org/wiki/DRMJanitors/#makepanichandlingwork > > > > > > Noralf Trønnes (3): > > drm: Add support for text framebuffer > > drm/text: Add panic and boot console support > > drm/text: Add VT console support > > > > drivers/gpu/drm/Makefile | 1 + > > drivers/gpu/drm/drm-text/Makefile | 5 + > > drivers/gpu/drm/drm-text/drm-text-buffer.c | 340 ++++++++++++++++++++++++++++ > > drivers/gpu/drm/drm-text/drm-text-console.c | 205 +++++++++++++++++ > > drivers/gpu/drm/drm-text/drm-text-debugfs.c | 295 ++++++++++++++++++++++++ > > drivers/gpu/drm/drm-text/drm-text-vt.c | 197 ++++++++++++++++ > > drivers/gpu/drm/drm-text/drm-text.h | 99 ++++++++ > > 7 files changed, 1142 insertions(+) > > create mode 100644 drivers/gpu/drm/drm-text/Makefile > > create mode 100644 drivers/gpu/drm/drm-text/drm-text-buffer.c > > create mode 100644 drivers/gpu/drm/drm-text/drm-text-console.c > > create mode 100644 drivers/gpu/drm/drm-text/drm-text-debugfs.c > > create mode 100644 drivers/gpu/drm/drm-text/drm-text-vt.c > > create mode 100644 drivers/gpu/drm/drm-text/drm-text.h > > > > -- > > 2.8.2 > > > > _______________________________________________ > > dri-devel mailing list > > dri-devel@xxxxxxxxxxxxxxxxxxxxx > > 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 _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
