drm/i915/bxt: IPC WA for Broxton
Display Workarounds #1135
If IPC is enabled in BXT, display underruns are observed.
WA: The Line Time programmed in the WM_LINETIME register should be
half of the actual calculated Line Time.
Programmed Line Time = 1/2*Calculated Line Time
Changes since V1:
- Add Workaround number in commit & code
Changes since V2 (from Paulo):
- Bikeshed white space and make the WA tag look like the others
Reviewed-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Signed-off-by: Mahesh Kumar <mahesh1.kumar@intel.com>
Signed-off-by: Paulo Zanoni <paulo.r.zanoni@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20161201154940.24446-3-mahesh1.kumar@intel.com
diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c
index 5fe27e4..d2cc28f 100644
--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -1239,6 +1239,8 @@ int i915_driver_load(struct pci_dev *pdev, const struct pci_device_id *ent)
intel_runtime_pm_enable(dev_priv);
+ dev_priv->ipc_enabled = false;
+
/* Everything is in place, we can now relax! */
DRM_INFO("Initialized %s %d.%d.%d %s for %s on minor %d\n",
driver.name, driver.major, driver.minor, driver.patchlevel,
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 33758ac..4eea925 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -2329,6 +2329,8 @@ struct drm_i915_private {
/* perform PHY state sanity checks? */
bool chv_phy_assert[2];
+ bool ipc_enabled;
+
/* Used to save the pipe-to-encoder mapping for audio */
struct intel_encoder *av_enc_map[I915_MAX_PIPES];
diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 4db6845..9ea3eee 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -3761,7 +3761,10 @@ skl_compute_wm_level(const struct drm_i915_private *dev_priv,
static uint32_t
skl_compute_linetime_wm(struct intel_crtc_state *cstate)
{
+ struct drm_atomic_state *state = cstate->base.state;
+ struct drm_i915_private *dev_priv = to_i915(state->dev);
uint32_t pixel_rate;
+ uint32_t linetime_wm;
if (!cstate->base.active)
return 0;
@@ -3771,8 +3774,14 @@ skl_compute_linetime_wm(struct intel_crtc_state *cstate)
if (WARN_ON(pixel_rate == 0))
return 0;
- return DIV_ROUND_UP(8 * cstate->base.adjusted_mode.crtc_htotal * 1000,
- pixel_rate);
+ linetime_wm = DIV_ROUND_UP(8 * cstate->base.adjusted_mode.crtc_htotal *
+ 1000, pixel_rate);
+
+ /* Display WA #1135: bxt. */
+ if (IS_BROXTON(dev_priv) && dev_priv->ipc_enabled)
+ linetime_wm = DIV_ROUND_UP(linetime_wm, 2);
+
+ return linetime_wm;
}
static void skl_compute_transition_wm(struct intel_crtc_state *cstate,