[Intel-gfx] [PATCH] drm/i915: Release power ref after updating wm

[Gabriel Feceoru]

On HSW/BDW there are random dmesg-warn errors while running kms tests, like:

[90587.867077] Call Trace:
[90587.867085]  [<ffffffff81403dae>] dump_stack+0x67/0x99
[90587.867094]  [<ffffffff810790f1>] warn_slowpath_common+0x81/0xc0
[90587.867099]  [<ffffffff81079177>] warn_slowpath_fmt+0x47/0x50
[90587.867150]  [<ffffffffa036e280>] hsw_write32+0x280/0x290 [i915]
[90587.867186]  [<ffffffffa0315cc8>] _ilk_disable_lp_wm+0x98/0xd0 [i915]
[90587.867222]  [<ffffffffa031b1f2>] ilk_program_watermarks+0x4a2/0x940 [i915]
[90587.867260]  [<ffffffffa031b6e0>] ilk_optimize_watermarks+0x50/0x70 [i915]
[90587.867311]  [<ffffffffa03894e2>] intel_atomic_commit+0x742/0x2170 [i915]
[90587.867319]  [<ffffffff810c06b0>] ? wait_woken+0xa0/0xa0
[90587.867326]  [<ffffffff81535062>] drm_atomic_commit+0x32/0x50
[90587.867333]  [<ffffffff8150fd89>] drm_atomic_helper_connector_dpms+0xe9/0x1a0
[90587.867340]  [<ffffffff81529acd>] drm_mode_obj_set_property_ioctl+0x21d/0x230
[90587.867346]  [<ffffffff81529b0b>] drm_mode_connector_property_set_ioctl+0x2b/0x30
[90587.867352]  [<ffffffff8151a7a6>] drm_ioctl+0x236/0x4f0
[90587.867358]  [<ffffffff81529ae0>] ? drm_mode_obj_set_property_ioctl+0x230/0x230
[90587.867366]  [<ffffffff811e90de>] do_vfs_ioctl+0x8e/0x680
[90587.867372]  [<ffffffff811f4f5a>] ? __fget_light+0x6a/0x90
[90587.867378]  [<ffffffff811e970c>] SyS_ioctl+0x3c/0x70
[90587.867386]  [<ffffffff817cbf9b>] entry_SYSCALL_64_fastpath+0x16/0x73

Since writing the watermarks requires MMIO access, this should be done before
releasing the power reference.

This clears the flip-flops in kms tests on HSW/BDW.

Signed-off-by: Gabriel Feceoru <gabriel.feceoru at intel.com>
---
 drivers/gpu/drm/i915/intel_display.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index ce55f0b..b141e52 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -13631,9 +13631,6 @@ static int intel_atomic_commit(struct drm_device *dev,
 			modeset_put_power_domains(dev_priv, put_domains[i]);
 	}
 
-	if (intel_state->modeset)
-		intel_display_power_put(dev_priv, POWER_DOMAIN_MODESET);
-
 	/*
 	 * Now that the vblank has passed, we can go ahead and program the
 	 * optimal watermarks on platforms that need two-step watermark
@@ -13648,6 +13645,9 @@ static int intel_atomic_commit(struct drm_device *dev,
 			dev_priv->display.optimize_watermarks(intel_cstate);
 	}
 
+	if (intel_state->modeset)
+		intel_display_power_put(dev_priv, POWER_DOMAIN_MODESET);
+
 	mutex_lock(&dev->struct_mutex);
 	drm_atomic_helper_cleanup_planes(dev, state);
 	mutex_unlock(&dev->struct_mutex);
-- 
1.9.1