[PATCH 18/49] drm/i915/bxt: add workaround to avoid PTE corruption

Imre Deak
2015-03-17T09:40:35Z

From: Robert Beckett <robert.beckett@intel.com>

Set TLBPF in TILECTL. This fixes an issue with BXT HW seeing
corrupted pte entries.

v2:
- move the workaround to bxt_init_clock_gating (imre)

Signed-off-by: Robert Beckett <robert.beckett@intel.com> (v1)
Signed-off-by: Imre Deak <imre.deak@intel.com>
---
drivers/gpu/drm/i915/i915_reg.h | 1 +
drivers/gpu/drm/i915/intel_pm.c | 2 ++
2 files changed, 3 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h
index 1d074e8..d69d7b9 100644
--- a/drivers/gpu/drm/i915/i915_reg.h
+++ b/drivers/gpu/drm/i915/i915_reg.h
@@ -1151,6 +1151,7 @@ enum skl_disp_power_wells {
/* control register for cpu gtt access */
#define TILECTL 0x101000
#define TILECTL_SWZCTL (1 << 0)
+#define TILECTL_TLBPF (1 << 1)
#define TILECTL_TLB_PREFETCH_DIS (1 << 2)
#define TILECTL_BACKSNOOP_DIS (1 << 3)

diff --git a/drivers/gpu/drm/i915/intel_pm.c b/drivers/gpu/drm/i915/intel_pm.c
index 52d3c02..d3f2557 100644
--- a/drivers/gpu/drm/i915/intel_pm.c
+++ b/drivers/gpu/drm/i915/intel_pm.c
@@ -110,6 +110,8 @@ static void bxt_init_clock_gating(struct drm_device *dev)
GEN8_SDEUNIT_CLOCK_GATE_DISABLE |
GEN8_HDCUNIT_CLOCK_GATE_DISABLE_HDCREQ);

+ /* FIXME: apply on A0 only */
+ I915_WRITE(TILECTL, I915_READ(TILECTL) | TILECTL_TLBPF);
}

static void i915_pineview_get_mem_freq(struct drm_device *dev)
--
2.1.0