On Thu, Dec 18, 2014 at 05:44:37AM +0000, Cheng, Yao wrote:
-----Original Message----- From: Thierry Reding [mailto:thierry.reding@gmail.com] Sent: Wednesday, December 17, 2014 16:13 To: Cheng, Yao Cc: Daniel Vetter; intel-gfx@lists.freedesktop.org; dri- devel@lists.freedesktop.org; daniel.vetter@ffwll.ch; Kelley, Sean V; Chehab, John; emil.l.velikov@gmail.com; Jiang, Fei Subject: Re: [RFC PATCH v3 4/4] tests/drv_module_reload: add ipvr support
Thanks Thiery for the suggestion, pls see my inline comments
Thierry/Daniel, the actual symptom is, after "rmmod i915", though drm_drv_release() is also called on the child device "ipvr", I still see the module exist in the system (check it by "lsmod").
Which module? ipvr or i915?
The ipvr module still exist by checking "lsmod" after rmmod i915
This causes issue when I modprobe i915 and ipvr again later.
What issue are you seeing? If your driver can't deal with a situation where it's probed again after being removed then you have a bug.
I double checked the symptom and found it was a deadlock on drm_global_mutex. When i915_driver_load() registers the platform device while ipvr module is in the system, ipvr's probe() function tries to lock drm_global_mutex which was already held by i915. I think either of the following 2 actions need to be moved to a bottom half e.g. a work queue: platform_device_add () call in i915_ved.c (called during i915_driver_load()) drm_dev_register() call during ipvr's probe() Which one makes more sense? pls kindly advise (I personally prefer the former one.).
Yes, that's somewhat ugly, but I don't see a way around that. I'd also think that moving platform_device_add() to a workqueue would be the best option here.
Thierry