Messages in this thread | | | Subject | Re: [PATCH v5 2/6] drm/bridge: Add a devm_ allocator for panel bridge. | From | Noralf Trønnes <> | Date | Sat, 5 Aug 2017 12:59:07 +0200 |
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(I had to switch to Daniel's Intel address to get this sent)
Den 05.08.2017 00.19, skrev Ilia Mirkin: > On Fri, Aug 4, 2017 at 4:43 PM, Eric Anholt <eric@anholt.net> wrote: >> Laurent Pinchart <laurent.pinchart@ideasonboard.com> writes: >> >>> Hi Eric, >>> >>> (CC'ing Daniel) >>> >>> Thank you for the patch. >>> >>> On Tuesday 18 Jul 2017 14:05:06 Eric Anholt wrote: >>>> This will let drivers reduce the error cleanup they need, in >>>> particular the "is_panel_bridge" flag. >>>> >>>> v2: Slight cleanup of remove function by Andrzej >>> I just want to point out that, in the context of Daniel's work on hot-unplug, >>> 90% of the devm_* allocations are wrong and will get in the way. All DRM core >>> objects that are accessible one way or another from userspace will need to be >>> properly reference-counted and freed only when the last reference disappears, >>> which could be well after the corresponding device is removed. I believe this >>> could be one such objects :-/ >> Sure, if you're hotplugging, your life is pain. For non-hotpluggable >> devices, like our SOC platform devices (current panel-bridge consumers), >> this still seems like an excellent simplification of memory management. > At that point you may as well make your module non-unloadable, and > return failure when trying to remove a device from management by the > driver (whatever the opposite of "probe" is, I forget). Hotplugging > doesn't only happen when physically removing, it can happen for all > kinds of reasons... and userspace may still hold references in some of > those cases.
If drm_open() gets a ref on dev->dev and puts it in drm_release(), won't that delay devm_* cleanup until userspace is done?
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