Re: [PATCH v2 00/11] drm/tinydrm: Support device unplug

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On 03/19/2018 03:45 PM, Daniel Vetter wrote:
On Sat, Mar 17, 2018 at 03:40:29PM +0100, Noralf Trønnes wrote:
Den 16.03.2018 09.03, skrev Daniel Vetter:
On Fri, Sep 8, 2017 at 6:33 PM, Daniel Vetter<daniel@xxxxxxxx>  wrote:
Hi Noralf,

On Fri, Sep 08, 2017 at 05:07:19PM +0200, Noralf Trønnes wrote:
This adds device unplug support to drm_fb_helper, drm_fb_cma_helper
(fbdev) and tinydrm.

There are several changes in this version:

I've used Daniel's idea of protecting drm_device.unplugged with srcu to
provide race free drm_dev_unplug().

The fbdev helper unplug patch has become very small with Daniel's help.
Ref is now taken and dropped in the existing helpers, so I could drop
drm_fb_helper_simple_init().

I has annoyed me that fbdev is restored in drm_driver.last_close even if
fbdev isn't used. I've added a patch to fix that. This means I can drop
calling drm_atomic_helper_shutdown() in tinydrm_unregister(), since I
now can easily disable the pipeline from userspace by just closing the
users. Disabled pipeline means balanced regulator_enable/disable.

The 'Embed drm_device in tinydrm_device' patch has gained
drm_driver.release functions after a discussion with Laurent. My
previous version relied on obscure freeing in tinydrm_release().
This means that I didn't retain the ack's.

Laurent also caught an ugly devm_kmalloc() in
tinydrm_display_pipe_init() that I've fixed.
I'm practically packing for my 2 weeks of conference travel already, so
only very cursory read of the initial patches for core&fb-helpers. I think
this looks really splendid now.

But I won't have time for review for the next few week, would be good if
you could drag some others into this discussions. Iirc there's recently
been a few different people interested in udl (even some patches I think),
they might be able to help out with testing&review.

Also, would be great if you can submit this to intel-gfx on the next
round, so that our CI can pick it up and give it a solid beating. Touching
critical core paths like in patch 1 is always a bit scary.
While reviewing xen-front's hotunplug handling I just realized this
never landed. Can you pls resend and nag me to review it properly? I'd
really like to get the drm_dev_unplug stuff sorted out better.
My plan was to pick this up after switching tinydrm over to vmalloc buffers,
but that work is now waiting for the generic fbdev emulation to land.

I'm currently wandering around inside drm_fb_helper looking for a way out,
I can feel the draft so there has to be an exit somewhere. I hope that in
a week or two I'm done with the next version of the RFC using the
drm_fb_helper mode setting code instead of the ioctl's.

At that point it will be a good thing to flush my "caches" of the
drm_fb_helper code, since after looking at it for a long time, I really
don't see the details anymore. So I'll pick up the unplug series then, at
least the core patches should be trivial to review and get merged if the CI
agrees.
Sounds great. I chatted some more with Oleksandr on irc and explained how
he can at least prototype correct unplug code using the current upstream
stuff. He's also willing to help get your stuff landed I think.
Yes, I can try helping with this - please let me know
if you need something.
And at least I can plumb that into my driver and have it tested.
  And afair
the unplug stuff pretty much looked ready for merging already, at least I
don't remember anything big pending.
-Daniel

Noralf.

Thanks, Daniel

Thanks, Daniel

Noralf.

Noralf Trønnes (11):
    drm: Use srcu to protect drm_device.unplugged
    drm/fb-helper: Support device unplug
    drm/fb-helper: Ensure driver module is pinned in fb_open()
    drm/fb-helper: Don't restore if fbdev is not in use
    drm/fb-cma-helper: Make struct drm_fbdev_cma public
    drm/fb-cma-helper: Support device unplug
    drm/tinydrm: Drop driver registered message
    drm/tinydrm: Embed drm_device in tinydrm_device
    drm/tinydrm: Support device unplug in core
    drm/tinydrm/mi0283qt: Let the display pipe handle power
    drm/tinydrm: Support device unplug in drivers

   drivers/gpu/drm/drm_drv.c                   |  54 +++++++++--
   drivers/gpu/drm/drm_fb_cma_helper.c         |  13 +--
   drivers/gpu/drm/drm_fb_helper.c             | 108 ++++++++++++++++++++--
   drivers/gpu/drm/tinydrm/core/tinydrm-core.c | 135 +++++++++++++++++++---------
   drivers/gpu/drm/tinydrm/core/tinydrm-pipe.c |  28 +++---
   drivers/gpu/drm/tinydrm/mi0283qt.c          |  81 +++++------------
   drivers/gpu/drm/tinydrm/mipi-dbi.c          |  58 +++++++++---
   drivers/gpu/drm/tinydrm/repaper.c           |  62 ++++++++-----
   drivers/gpu/drm/tinydrm/st7586.c            |  54 ++++++-----
   include/drm/drm_device.h                    |   9 +-
   include/drm/drm_drv.h                       |  15 +++-
   include/drm/drm_fb_cma_helper.h             |  11 ++-
   include/drm/drm_fb_helper.h                 |  28 ++++++
   include/drm/tinydrm/mipi-dbi.h              |   1 +
   include/drm/tinydrm/tinydrm.h               |  10 ++-
   15 files changed, 469 insertions(+), 198 deletions(-)

--
2.7.4

--
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch
-- Daniel Vetter Software Engineer, Intel Corporation +41 (0) 79 365 57
48 - http://blog.ffwll.ch

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