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>
diff --git a/drivers/gpu/drm/i915/intel_hdmi.c b/drivers/gpu/drm/i915/intel_hdmi.c
index c16fb34..847ff20 100644
--- a/drivers/gpu/drm/i915/intel_hdmi.c
+++ b/drivers/gpu/drm/i915/intel_hdmi.c
@@ -1019,6 +1019,7 @@
return;
/* Enable clock channels for this port */
+ mutex_lock(&dev_priv->dpio_lock);
val = vlv_dpio_read(dev_priv, DPIO_DATA_LANE_A(port));
val = 0;
if (pipe)
@@ -1049,6 +1050,7 @@
0x00760018);
vlv_dpio_write(dev_priv, DPIO_PCS_CLOCKBUF8(port),
0x00400888);
+ mutex_unlock(&dev_priv->dpio_lock);
}
static void intel_hdmi_pre_pll_enable(struct intel_encoder *encoder)
@@ -1062,6 +1064,7 @@
return;
/* Program Tx lane resets to default */
+ mutex_lock(&dev_priv->dpio_lock);
vlv_dpio_write(dev_priv, DPIO_PCS_TX(port),
DPIO_PCS_TX_LANE2_RESET |
DPIO_PCS_TX_LANE1_RESET);
@@ -1080,6 +1083,7 @@
0x00002000);
vlv_dpio_write(dev_priv, DPIO_TX_OCALINIT(port),
DPIO_TX_OCALINIT_EN);
+ mutex_unlock(&dev_priv->dpio_lock);
}
static void intel_hdmi_post_disable(struct intel_encoder *encoder)