On Thu, Jan 14, 2016 at 02:30:50PM -0800, Stefan Agner wrote: > Hi Mark, > > I currently work on the DCU DRM driver (drivers/gpu/drm/fsl-dcu/) on a > Linux 4.4 kernel. With CONFIG_LOCKDEP enabled I get the following > warning on startup: > > [ 1.327284] ------------[ cut here ]------------ > [ 1.332010] WARNING: CPU: 0 PID: 1 at kernel/locking/lockdep.c:2755 lockdep_trace_alloc+0x120/0x124() > [ 1.341358] DEBUG_LOCKS_WARN_ON(irqs_disabled_flags(flags)) > [ 1.521744] [<80375308>] (_regmap_write) from [<80376760>] (regmap_write+0x48/0x68) > [ 1.535348] [<80376718>] (regmap_write) from [<803538e8>] (fsl_dcu_drm_crtc_create+0x98/0xe8) > [ 1.549824] [<80353850>] (fsl_dcu_drm_crtc_create) from [<80352df0>] (fsl_dcu_drm_modeset_init+0x5c/0xfc) > The comment in __lockdep_trace_alloc says: > "Oi! Can't be having __GFP_FS allocations with IRQs disabled.". So _regmap_write() does: map->lock(map->lock_arg) Which isn't very enlightening, since that can be a mutex or a spinlock, the above strongly suggests spinlock though. Looking at __regmap_init(), this seems to depend on: (bus && bus->fast_io) || config->fast_io now, afaict, regmap_mmio is used in this case, which has .fast_io = true. So yeah, fail. _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel
