[PATCH 0/3] fbdev no more!

[Daniel Vetter]

On Mon, Jun 17, 2013 at 4:33 PM, Konrad Rzeszutek Wilk
<konrad.wilk at oracle.com> wrote:
> On Sun, Jun 16, 2013 at 04:57:17PM +0200, Daniel Vetter wrote:
>> Hi all,
>>
>> So I've taken a look again at the locking mess in our fbdev support and cried.
>> Fixing up the console_lock mess around the fbdev notifier will be real work,
>> semanatically the fbdev layer does lots of stupid things (like the radeon resume
>> issue I've just debugged) and the panic notifier is pretty much a lost cause.
>>
>> So I've decided to instead rip it all out. It seems to work \o/
>
>
> When you say 'locking mess in our fbdev support' you mean the general
> core fbdev driver? Not neccessarily the i915 driver?
>
> I am asking b/c that would imply that the other fbdev drivers still hit
> the locking mess?

Yeah, the recent thing I've stumbled over is how the the fbdev/fbcon
locking proliferates console_lock protected sections like mad. Which
means that the initial modeset (for fbcon) is all done with the
console_lock held. Which makes debugging things in that rather tricky
code a mess. So nothing i915-specifc.
-Daniel

>
> Thanks!
>>
>> Of course a general purpose distro propably wants David's kmscon for any
>> fallbacks needs and a system compositor to ditch the VT subsystem - atm my
>> machine here runs with the dummy console so that VT switching between different
>> X sessions still works ;-)
>>
>> Oh and: At least fedora's boot splash seems to be unhappy about the lack of an
>> fbdev (it doesn't seem to do anything), which breaks early disk encryption a
>> bit. The black screen itself shouldn't be a big issue at least for i915, since
>> with all the fastboot work we can just hang onto the current config and
>> framebuffer (one missing patch from Chris for the fb preservartion). So as long
>> as the bios/grub put up something nice, it'll look ok.
>>
>> So just a small step here really, but imo into the right direction. Now, please
>> bring on the flames!
>>
>> Aside: We can hide the #ifdef mess a bit better in drm/i915 I think, but I'd
>> like to wait for a bit of feedback first. And one more: This also removes the
>> console_lock completely from our critical path in suspend/resume!
>>
>> One thing I haven't wasted a single thought about is kgdb and panic notifier
>> support. But since the current code is pretty decently broken already (we have
>> _tons_ of mutex grabbing and waits in there) I don't think people care that much
>> about it anyway. Using a sprite to smash the kgdb/panic output on top of
>> whatever's currently displaying might be an approach.
>>
>> Cheers, Daniel
>>
>> Daniel Vetter (3):
>>   drm: Add separate Kconfig option for fbdev helpers
>>   drm/i915: Kconfig option to disable the legacy fbdev support
>>   drm/i915: rename intel_fb.c to intel_fbdev.c
>>
>>  drivers/gpu/drm/Kconfig              |  57 ++-----
>>  drivers/gpu/drm/Makefile             |   3 +-
>>  drivers/gpu/drm/ast/Kconfig          |   1 +
>>  drivers/gpu/drm/cirrus/Kconfig       |   1 +
>>  drivers/gpu/drm/exynos/Kconfig       |   1 +
>>  drivers/gpu/drm/gma500/Kconfig       |   1 +
>>  drivers/gpu/drm/i915/Kconfig         |  56 +++++++
>>  drivers/gpu/drm/i915/Makefile        |   3 +-
>>  drivers/gpu/drm/i915/i915_debugfs.c  |   4 +-
>>  drivers/gpu/drm/i915/i915_dma.c      |   8 +-
>>  drivers/gpu/drm/i915/i915_drv.h      |   2 +
>>  drivers/gpu/drm/i915/intel_display.c |  12 +-
>>  drivers/gpu/drm/i915/intel_drv.h     |  39 ++++-
>>  drivers/gpu/drm/i915/intel_fb.c      | 314 -----------------------------------
>>  drivers/gpu/drm/i915/intel_fbdev.c   | 314 +++++++++++++++++++++++++++++++++++
>>  drivers/gpu/drm/mgag200/Kconfig      |   1 +
>>  drivers/gpu/drm/nouveau/Kconfig      |   1 +
>>  drivers/gpu/drm/omapdrm/Kconfig      |   1 +
>>  drivers/gpu/drm/qxl/Kconfig          |   1 +
>>  drivers/gpu/drm/shmobile/Kconfig     |   1 +
>>  drivers/gpu/drm/tilcdc/Kconfig       |   1 +
>>  drivers/gpu/drm/udl/Kconfig          |   1 +
>>  drivers/gpu/host1x/drm/Kconfig       |   1 +
>>  drivers/staging/imx-drm/Kconfig      |   1 +
>>  24 files changed, 452 insertions(+), 373 deletions(-)
>>  create mode 100644 drivers/gpu/drm/i915/Kconfig
>>  delete mode 100644 drivers/gpu/drm/i915/intel_fb.c
>>  create mode 100644 drivers/gpu/drm/i915/intel_fbdev.c
>>
>> --
>> 1.7.11.7
>>
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--
Daniel Vetter
Software Engineer, Intel Corporation
+41 (0) 79 365 57 48 - http://blog.ffwll.ch