> -----Original Message----- > From: Daniel Vetter [mailto:daniel.vetter@xxxxxxxx] > Sent: Thursday, December 18, 2014 19:21 > To: Thierry Reding > Cc: Cheng, Yao; intel-gfx@xxxxxxxxxxxxxxxxxxxxx; dri- > devel@xxxxxxxxxxxxxxxxxxxxx; Kelley, Sean V; Chehab, John; > emil.l.velikov@xxxxxxxxx; Jiang, Fei > Subject: Re: [RFC PATCH v3 4/4] tests/drv_module_reload: add ipvr support > > On Thu, Dec 18, 2014 at 11:04 AM, Thierry Reding <thierry.reding@xxxxxxxxx> > wrote: > >> 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. > > Or we simply kill drm_global_mutex for platform drivers that don't use the - > >probe hook. It should work when they have a correct order betwen > drm_dev_alloc and _register and all the code in between. So just ditch the - > >load callback in teh ipvr driver and rework the load sequence as suggested > somewhere else and this is fixed already. No need for bottom halfs I think. Daniel, sorry I didn't quite understand "platform drivers that don't use the probe hook". For initialization, the ipvr platform driver's probe() is called in following 2 possible paths: 1. ipvr installed before i915. In this case, ipvr's probe() is called inside i915_driver_load() and falls into the drm_global_mutex dead lock. 2. i915 installed before ipvr. In this case, ipvr's probe() is called without drm_global_mutex held by i915 and no dead lock issue. If we kill drm_global_mutex, will path 2 run into issue? And in your suggestion, how to rework the load sequence? Do you mean calling ipvr's load() callback directly during platform driver probe()? > -Daniel > -- > Daniel Vetter > Software Engineer, Intel Corporation > +41 (0) 79 365 57 48 - http://blog.ffwll.ch _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel
