drm/i915: Acquire dpio_lock for VLV sideband programming in DP/HDMI
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
v2: Retire the locking in vlv_crtc_enable() and do it close to the meat.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
[danvet: Squash in a s/mutex_lock/mutex_unlock/ fixup spotted by the 0
day kernel build/coccinelle and reported by Dan Carpenter.]
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
3 files changed