[PATCH v2 00/11] drm/tinydrm: Support device unplug
Noralf Trønnes
noralf at tronnes.org
Mon Mar 26 16:36:38 UTC 2018
Den 26.03.2018 15.02, skrev Oleksandr Andrushchenko:
> Hi, Noralf!
>
> On 03/17/2018 04:40 PM, Noralf Trønnes wrote:
>>
>> Den 16.03.2018 09.03, skrev Daniel Vetter:
>>> On Fri, Sep 8, 2017 at 6:33 PM, Daniel Vetter<daniel at ffwll.ch> 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.
> Could you please estimate when unplug series can be on review?
> I am doing some unplug work in my PV DRM driver and would like
> to understand if it is feasible to wait for you or post patches as
> they are
> and then plumb in drm_dev_{enter|exit} later after your work is merged
>
Ok, so I have looked at the patches and some work I have lying around.
As things stand now I see an opportunity to move some stuff from tinydrm
into drm_simple_kms_helper as part of adding unplug support to tinydrm.
This also depends on the generic fbdev emulation I'm working on.
This all means that it won't be some trivial tweaking to the unplug
patchset before resending it. It will take some time.
My suggestion is that you just add the core unplug patch as part of your
driver submission instead of waiting for me.
drm: Use srcu to protect drm_device.unplugged
https://patchwork.freedesktop.org/patch/175779/
I believe this patch should be good to go as-is. Please CC
intel-gfx at lists.freedesktop.org if you do so to have the Intel CI verify it.
As for drm_fb_helper unplug support:
drm/fb-helper: Support device unplug
https://patchwork.freedesktop.org/patch/175785/
I'm not as confident in this one since I'm not sure that those
drm_dev_is_unplugged() checks are really necessary. The driver has to do
the check anyways. But this patch isn't necessary for you to do most of
your driver side unplug protection though. You can do testing without
fbdev enabled and let me to care of this when I get around to it.
I you pick up the patch(es) and need to change something, you don't have
to bother with retaining my authorship (but please cc me). Just claim it
for your own and make it work.
Less work for me when I get there (eventually).
Noralf.
> Thank you,
> Oleksandr
>>
>> 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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