From: Chris Wilson <chris at chris-wilson.co.uk> As a w/a to prevent reads sporadically returning 0, we need to wait for the GT thread to return to TC0 before proceeding to read the registers. v2: adapt for Haswell changes (Eugeni). References: https://bugs.freedesktop.org/show_bug.cgi?id=50243 Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk> Signed-off-by: Eugeni Dodonov <eugeni.dodonov at intel.com> --- drivers/gpu/drm/i915/i915_drv.c | 25 +++++++++++++++++++++++++ drivers/gpu/drm/i915/i915_reg.h | 4 ++++ 2 files changed, 29 insertions(+) diff --git a/drivers/gpu/drm/i915/i915_drv.c b/drivers/gpu/drm/i915/i915_drv.c index e7b989b..3ef2103 100644 --- a/drivers/gpu/drm/i915/i915_drv.c +++ b/drivers/gpu/drm/i915/i915_drv.c @@ -433,6 +433,25 @@ bool i915_semaphore_is_enabled(struct drm_device *dev) return 1; } +static void __gen6_gt_wait_for_thread_c0(struct drm_i915_private *dev_priv) +{ + unsigned long timeout; + u32 gt_thread_status_mask; + + if (IS_HASWELL(dev_priv->dev)) + gt_thread_status_mask = GEN6_GT_THREAD_STATUS_CORE_MASK_HSW; + else + gt_thread_status_mask = GEN6_GT_THREAD_STATUS_CORE_MASK; + + /* w/a for a sporadic read returning 0 by waiting for the GT + * thread to wake up. + */ + timeout = jiffies + msecs_to_jiffies(1); + while (I915_READ_NOTRACE(GEN6_GT_THREAD_STATUS_REG) & gt_thread_status_mask && + time_before(jiffies, timeout)) + ; +} + static void __gen6_gt_force_wake_get(struct drm_i915_private *dev_priv) { unsigned long timeout; @@ -448,6 +467,8 @@ static void __gen6_gt_force_wake_get(struct drm_i915_private *dev_priv) while ((I915_READ_NOTRACE(FORCEWAKE_ACK) & 1) == 0 && time_before(jiffies, timeout)) ; + + __gen6_gt_wait_for_thread_c0(dev_priv); } static void __gen6_gt_force_wake_mt_get(struct drm_i915_private *dev_priv) @@ -465,6 +486,8 @@ static void __gen6_gt_force_wake_mt_get(struct drm_i915_private *dev_priv) while ((I915_READ_NOTRACE(FORCEWAKE_MT_ACK) & 1) == 0 && time_before(jiffies, timeout)) ; + + __gen6_gt_wait_for_thread_c0(dev_priv); } /* @@ -555,6 +578,8 @@ static void vlv_force_wake_get(struct drm_i915_private *dev_priv) count = 0; while (count++ < 50 && (I915_READ_NOTRACE(FORCEWAKE_ACK_VLV) & 1) == 0) udelay(10); + + __gen6_gt_wait_for_thread_c0(dev_priv); } static void vlv_force_wake_put(struct drm_i915_private *dev_priv) diff --git a/drivers/gpu/drm/i915/i915_reg.h b/drivers/gpu/drm/i915/i915_reg.h index d8f516b..20f7f0d 100644 --- a/drivers/gpu/drm/i915/i915_reg.h +++ b/drivers/gpu/drm/i915/i915_reg.h @@ -1458,6 +1458,10 @@ #define DDRMPLL1 0X12c20 #define PEG_BAND_GAP_DATA 0x14d68 +#define GEN6_GT_THREAD_STATUS_REG 0x13805c +#define GEN6_GT_THREAD_STATUS_CORE_MASK 0x7 +#define GEN6_GT_THREAD_STATUS_CORE_MASK_HSW (0x7 | (0x07 << 16)) + #define GEN6_GT_PERF_STATUS 0x145948 #define GEN6_RP_STATE_LIMITS 0x145994 #define GEN6_RP_STATE_CAP 0x145998 -- 1.7.11.1
