Re: [PATCH 50/51] drm/udl: drop drm_driver.release hook

[Thomas Zimmermann <tzimmermann@suse.de>]

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Hi Daniel

Am 28.02.20 um 18:43 schrieb Daniel Vetter:
> On Fri, Feb 28, 2020 at 12:46 PM Thomas Zimmermann <tzimmermann@suse.de> wrote:
>>
>> Hi
>>
>> Am 28.02.20 um 09:40 schrieb Daniel Vetter:
>>> On Fri, Feb 28, 2020 at 8:44 AM Thomas Zimmermann <tzimmermann@suse.de> wrote:
>>>>
>>>> Hi Daniel
>>>>
>>>> Am 27.02.20 um 19:15 schrieb Daniel Vetter:
>>>>> There's only two functions called from that:
>>>>> drm_kms_helper_poll_fini() and udl_free_urb_list(). Both of these are
>>>>> also called from the ubs_driver->disconnect hook, so entirely
>>>>> pointless to do the same again in the ->release hook.
>>>>
>>>> The disconnect hook calls drm_kms_helper_poll_disable() instead if
>>>> _fini(). They are the same, except that _disable() does not clear
>>>> dev->mode_config.poll_enabled to false. Is this OK?
>>>
>>> oops, I overlooked that. But yeah for driver shutdown it's the same
>>> really, we're not going to re-enable. _disable is meant for suspend so
>>> youc an re-enable again on resume.
>>>
>>> I'll augment the commit message on the next round to clarify that.
>>
>> Well, we have a managed API. It could support
>> drmm_kms_helper_poll_init(). :)
> 
> You're ahead of the game here, but yes that's the plan. And a lot
> more. Ideally I really want to get rid of both bus_driver->remove and
> drm_driver->release callbacks for all drivers.
> 
> Also, for polling you actually want devm_kms_poll_init, since polling
> should be stopped at unplug/remove time. Not at drm_driver release
> time :-)

Quite honestly, if you're not adding devm_kms_poll_init() now, why even
bother removing the _fini() call from release()? It hasn't been a
problem so far and it won't become one. Doing a half-baked change now
results in a potential WTF moment for other developers.

Rather clean up release() when you add the managed devm_kms_poll_init()
and have a nice, clear patch.

Best regards
Thomas


> -Daniel
> 
>>
>> Best regards
>> Thomas
>>
>>> -Daniel
>>>
>>>
>>>> Best regards
>>>> Thomas
>>>>
>>>>>
>>>>> Furthermore by the time we clean up the drm_driver we really shouldn't
>>>>> be touching hardware anymore, so stopping the poll worker and freeing
>>>>> the urb allocations in ->disconnect is the right thing to do.
>>>>>
>>>>> Now disconnect still cleans things up before unregistering the driver,
>>>>> but that's a different issue.
>>>>>
>>>>> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
>>>>> Cc: Dave Airlie <airlied@redhat.com>
>>>>> Cc: Sean Paul <sean@poorly.run>
>>>>> Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
>>>>> Cc: Thomas Zimmermann <tzimmermann@suse.de>
>>>>> Cc: Emil Velikov <emil.l.velikov@gmail.com>
>>>>> Cc: Gerd Hoffmann <kraxel@redhat.com>
>>>>> Cc: "Noralf Trønnes" <noralf@tronnes.org>
>>>>> Cc: Sam Ravnborg <sam@ravnborg.org>
>>>>> Cc: Thomas Gleixner <tglx@linutronix.de>
>>>>> Cc: Alex Deucher <alexander.deucher@amd.com>
>>>>> ---
>>>>>  drivers/gpu/drm/udl/udl_drv.c  |  6 ------
>>>>>  drivers/gpu/drm/udl/udl_drv.h  |  1 -
>>>>>  drivers/gpu/drm/udl/udl_main.c | 10 ----------
>>>>>  3 files changed, 17 deletions(-)
>>>>>
>>>>> diff --git a/drivers/gpu/drm/udl/udl_drv.c b/drivers/gpu/drm/udl/udl_drv.c
>>>>> index b447fb053e78..7f140898df3e 100644
>>>>> --- a/drivers/gpu/drm/udl/udl_drv.c
>>>>> +++ b/drivers/gpu/drm/udl/udl_drv.c
>>>>> @@ -34,14 +34,8 @@ static int udl_usb_resume(struct usb_interface *interface)
>>>>>
>>>>>  DEFINE_DRM_GEM_FOPS(udl_driver_fops);
>>>>>
>>>>> -static void udl_driver_release(struct drm_device *dev)
>>>>> -{
>>>>> -     udl_fini(dev);
>>>>> -}
>>>>> -
>>>>>  static struct drm_driver driver = {
>>>>>       .driver_features = DRIVER_ATOMIC | DRIVER_GEM | DRIVER_MODESET,
>>>>> -     .release = udl_driver_release,
>>>>>
>>>>>       /* gem hooks */
>>>>>       .gem_create_object = udl_driver_gem_create_object,
>>>>> diff --git a/drivers/gpu/drm/udl/udl_drv.h b/drivers/gpu/drm/udl/udl_drv.h
>>>>> index 1de7eb1b6aac..2642f94a63fc 100644
>>>>> --- a/drivers/gpu/drm/udl/udl_drv.h
>>>>> +++ b/drivers/gpu/drm/udl/udl_drv.h
>>>>> @@ -76,7 +76,6 @@ int udl_submit_urb(struct drm_device *dev, struct urb *urb, size_t len);
>>>>>  void udl_urb_completion(struct urb *urb);
>>>>>
>>>>>  int udl_init(struct udl_device *udl);
>>>>> -void udl_fini(struct drm_device *dev);
>>>>>
>>>>>  int udl_render_hline(struct drm_device *dev, int log_bpp, struct urb **urb_ptr,
>>>>>                    const char *front, char **urb_buf_ptr,
>>>>> diff --git a/drivers/gpu/drm/udl/udl_main.c b/drivers/gpu/drm/udl/udl_main.c
>>>>> index 538718919916..f5d27f2a5654 100644
>>>>> --- a/drivers/gpu/drm/udl/udl_main.c
>>>>> +++ b/drivers/gpu/drm/udl/udl_main.c
>>>>> @@ -351,13 +351,3 @@ int udl_drop_usb(struct drm_device *dev)
>>>>>       udl_free_urb_list(dev);
>>>>>       return 0;
>>>>>  }
>>>>> -
>>>>> -void udl_fini(struct drm_device *dev)
>>>>> -{
>>>>> -     struct udl_device *udl = to_udl(dev);
>>>>> -
>>>>> -     drm_kms_helper_poll_fini(dev);
>>>>> -
>>>>> -     if (udl->urbs.count)
>>>>> -             udl_free_urb_list(dev);
>>>>> -}
>>>>>
>>>>
>>>> --
>>>> Thomas Zimmermann
>>>> Graphics Driver Developer
>>>> SUSE Software Solutions Germany GmbH
>>>> Maxfeldstr. 5, 90409 Nürnberg, Germany
>>>> (HRB 36809, AG Nürnberg)
>>>> Geschäftsführer: Felix Imendörffer
>>>>
>>>
>>>
>>
>> --
>> Thomas Zimmermann
>> Graphics Driver Developer
>> SUSE Software Solutions Germany GmbH
>> Maxfeldstr. 5, 90409 Nürnberg, Germany
>> (HRB 36809, AG Nürnberg)
>> Geschäftsführer: Felix Imendörffer
>>
> 
> 

-- 
Thomas Zimmermann
Graphics Driver Developer
SUSE Software Solutions Germany GmbH
Maxfeldstr. 5, 90409 Nürnberg, Germany
(HRB 36809, AG Nürnberg)
Geschäftsführer: Felix Imendörffer


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