On Fri, Jul 26, 2013 at 06:46:43PM +0200, Daniel Vetter wrote: > On Fri, Jul 26, 2013 at 6:17 PM, Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> wrote: > > Otherwise we get flooded by the kernel warning us that we are doing > > long sequences of IO without serialisation. For example, > > > > WARNING: CPU: 0 PID: 11136 at drivers/gpu/drm/i915/intel_sideband.c:40 vlv_sideband_rw+0x48/0x1ef() > > Modules linked in: > > CPU: 0 PID: 11136 Comm: kworker/u2:0 Tainted: G W 3.11.0-rc2+ #4 > > Call Trace: > > [<c2028564>] ? warn_slowpath_common+0x63/0x78 > > [<c227ad43>] ? vlv_sideband_rw+0x48/0x1ef > > [<c20285dd>] ? warn_slowpath_null+0xf/0x13 > > [<c227ad43>] ? vlv_sideband_rw+0x48/0x1ef > > [<c227b060>] ? vlv_dpio_write+0x1c/0x21 > > [<c2262b3b>] ? intel_dp_set_signal_levels+0x24a/0x385 > > [<c2264909>] ? intel_dp_complete_link_train+0x25/0x1d1 > > [<c2264c55>] ? intel_dp_check_link_status+0xf7/0x106 > > [<c2238ced>] ? i915_hotplug_work_func+0x17b/0x221 > > [<c203a204>] ? process_one_work+0x12e/0x210 > > [<c203a5e4>] ? worker_thread+0x116/0x1ad > > [<c203a4ce>] ? rescuer_thread+0x1cb/0x1cb > > [<c203d8f5>] ? kthread+0x67/0x6c > > [<c2457ebb>] ? ret_from_kernel_thread+0x1b/0x30 > > [<c203d88e>] ? init_completion+0x18/0x18 > > > > Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> > > The problem here is that Jesse was lazy and grabs the lock in > vlv_crtc_enable, so I think your code here will deadlock. But I agree > that grabbing the lock where we actually frob the sideband is what we > want ... Looks like vlv_crtc_enable() is the only place that takes the lock around callbacks, so I propose dropping the locking in that function (and scoping it around the sideband sequences as above). -Chris -- Chris Wilson, Intel Open Source Technology Centre _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/intel-gfx
