kernel/0008-drm-i915-Add-distrust_bios_wm-flag-to-dev_priv-v2.patch

From 7207eecfcb3095442bce30227b551003edc7b908 Mon Sep 17 00:00:00 2001
From: Matt Roper <matthew.d.roper@intel.com>
Date: Thu, 12 May 2016 07:06:02 -0700
Subject: [PATCH 08/17] drm/i915: Add distrust_bios_wm flag to dev_priv (v2)

SKL-style platforms can't fully trust the watermark/DDB settings
programmed by the BIOS and need to do extra sanitization on their first
atomic update.  Add a flag to dev_priv that is set during hardware
readout and cleared at the end of the first commit.

Note that for the somewhat common case where everything is turned off
when the driver starts up, we don't need to bother with a recompute...we
know exactly what the DDB should be (all zero's) so just setup the DDB
directly in that case.

v2:
 - Move clearing of distrust_bios_wm up below the swap_state call since
   it's a more natural / self-explanatory location.  (Maarten)
 - Use dev_priv->active_crtcs to test whether any CRTC's are turned on
   during HW WM readout rather than trying to count the active CRTC's
   again ourselves.  (Maarten)

Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Signed-off-by: Matt Roper <matthew.d.roper@intel.com>
Reviewed-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1463061971-19638-9-git-send-email-matthew.d.roper@intel.com
---
 drivers/gpu/drm/i915/i915_drv.h      | 7 +++++++
 drivers/gpu/drm/i915/intel_display.c | 1 +
 drivers/gpu/drm/i915/intel_pm.c      | 8 ++++++++
 3 files changed, 16 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 611c128..e21960d 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -1981,6 +1981,13 @@ struct drm_i915_private {
 		 * cstate->wm.need_postvbl_update.
 		 */
 		struct mutex wm_mutex;
+
+		/*
+		 * Set during HW readout of watermarks/DDB.  Some platforms
+		 * need to know when we're still using BIOS-provided values
+		 * (which we don't fully trust).
+		 */
+		bool distrust_bios_wm;
 	} wm;
 
 	struct i915_runtime_pm pm;
diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c
index f26d1c5..a9d2e30 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -13621,6 +13621,7 @@ static int intel_atomic_commit(struct drm_device *dev,
 
 	drm_atomic_helper_swap_state(dev, state);
 	dev_priv->wm.config = intel_state->wm_config;
+	dev_priv->wm.distrust_bios_wm = false;
 	intel_shared_dpll_commit(state);
 
 	if (intel_state->modeset) {
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index f009d43..a49faa7 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -4026,6 +4026,14 @@ void skl_wm_get_hw_state(struct drm_device *dev)
 	list_for_each_entry(crtc, &dev->mode_config.crtc_list, head)
 		skl_pipe_wm_get_hw_state(crtc);
 
+	if (dev_priv->active_crtcs) {
+		/* Fully recompute DDB on first atomic commit */
+		dev_priv->wm.distrust_bios_wm = true;
+	} else {
+		/* Easy/common case; just sanitize DDB now if everything off */
+		memset(ddb, 0, sizeof(*ddb));
+	}
+
 	/* Calculate plane data rates */
 	for_each_intel_crtc(dev, intel_crtc) {
 		struct intel_crtc_state *cstate = intel_crtc->config;
-- 
2.7.4