[PATCH v2 2/8] drm/i915: Add more control to wait_for routines

[Sean Paul <seanpaul@chromium.org>]

This patch adds a little more control to a couple wait_for routines such
that we can avoid open-coding read/wait/timeout patterns which:
 - need the value of the register after the wait_for
 - run arbitrary operation for the read portion

This patch also chooses the correct sleep function (based on
timers-howto.txt) for the polling interval the caller specifies.

Changes in v2:
- Added to the series

Suggested-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Sean Paul <seanpaul@chromium.org>
---
 drivers/gpu/drm/i915/intel_drv.h    | 17 ++++++++++++-----
 drivers/gpu/drm/i915/intel_uncore.c | 23 ++++++++++++++++-------
 drivers/gpu/drm/i915/intel_uncore.h | 14 +++++++++++++-
 3 files changed, 41 insertions(+), 13 deletions(-)

diff --git a/drivers/gpu/drm/i915/intel_drv.h b/drivers/gpu/drm/i915/intel_drv.h
index 69aab324aaa1..191c80fc4314 100644
--- a/drivers/gpu/drm/i915/intel_drv.h
+++ b/drivers/gpu/drm/i915/intel_drv.h
@@ -41,19 +41,21 @@
 #include <drm/drm_atomic.h>
 
 /**
- * _wait_for - magic (register) wait macro
+ * __wait_for - magic wait macro
  *
- * Does the right thing for modeset paths when run under kdgb or similar atomic
- * contexts. Note that it's important that we check the condition again after
+ * Macro to help avoid open coding check/wait/timeout patterns, will do the
+ * right think wrt to choosing msleep vs usleep_range based on how long the wait
+ * interval is. Note that it's important that we check the condition again after
  * having timed out, since the timeout could be due to preemption or similar and
  * we've never had a chance to check the condition before the timeout.
  */
-#define _wait_for(COND, US, W) ({ \
+#define __wait_for(OP, COND, US, W) ({ \
 	unsigned long timeout__ = jiffies + usecs_to_jiffies(US) + 1;	\
 	int ret__;							\
 	might_sleep();							\
 	for (;;) {							\
 		bool expired__ = time_after(jiffies, timeout__);	\
+		OP;							\
 		if (COND) {						\
 			ret__ = 0;					\
 			break;						\
@@ -62,11 +64,16 @@
 			ret__ = -ETIMEDOUT;				\
 			break;						\
 		}							\
-		usleep_range((W), (W) * 2);				\
+		if (W > (20 * 1000))					\
+			msleep(W / 1000);				\
+		else							\
+			usleep_range((W), (W) * 2);			\
 	}								\
 	ret__;								\
 })
 
+#define _wait_for(COND, US, W)		__wait_for(;,(COND), US, W)
+
 #define wait_for(COND, MS)	  	_wait_for((COND), (MS) * 1000, 1000)
 
 /* If CONFIG_PREEMPT_COUNT is disabled, in_atomic() always reports false. */
diff --git a/drivers/gpu/drm/i915/intel_uncore.c b/drivers/gpu/drm/i915/intel_uncore.c
index b4621271e7a2..c851b0c0602d 100644
--- a/drivers/gpu/drm/i915/intel_uncore.c
+++ b/drivers/gpu/drm/i915/intel_uncore.c
@@ -1770,12 +1770,14 @@ int __intel_wait_for_register_fw(struct drm_i915_private *dev_priv,
 }
 
 /**
- * intel_wait_for_register - wait until register matches expected state
+ * __intel_wait_for_register - wait until register matches expected state
  * @dev_priv: the i915 device
  * @reg: the register to read
  * @mask: mask to apply to register value
  * @value: expected value
- * @timeout_ms: timeout in millisecond
+ * @fast_timeout_us: fast timeout in microsecond for atomic/tight wait
+ * @slow_timeout_ms: slow timeout in millisecond
+ * @out_value: optional placeholder to hold registry value
  *
  * This routine waits until the target register @reg contains the expected
  * @value after applying the @mask, i.e. it waits until ::
@@ -1786,15 +1788,18 @@ int __intel_wait_for_register_fw(struct drm_i915_private *dev_priv,
  *
  * Returns 0 if the register matches the desired condition, or -ETIMEOUT.
  */
-int intel_wait_for_register(struct drm_i915_private *dev_priv,
+int __intel_wait_for_register(struct drm_i915_private *dev_priv,
 			    i915_reg_t reg,
 			    u32 mask,
 			    u32 value,
-			    unsigned int timeout_ms)
+			    unsigned int fast_timeout_us,
+			    unsigned int slow_timeout_ms,
+			    u32 *out_value)
 {
 	unsigned fw =
 		intel_uncore_forcewake_for_reg(dev_priv, reg, FW_REG_READ);
 	int ret;
+	u32 reg_value;
 
 	might_sleep();
 
@@ -1803,14 +1808,18 @@ int intel_wait_for_register(struct drm_i915_private *dev_priv,
 
 	ret = __intel_wait_for_register_fw(dev_priv,
 					   reg, mask, value,
-					   2, 0, NULL);
+					   fast_timeout_us, 0, &reg_value);
 
 	intel_uncore_forcewake_put__locked(dev_priv, fw);
 	spin_unlock_irq(&dev_priv->uncore.lock);
 
 	if (ret)
-		ret = wait_for((I915_READ_NOTRACE(reg) & mask) == value,
-			       timeout_ms);
+		ret = __wait_for(reg_value = I915_READ_NOTRACE(reg),
+			         (reg_value & mask) == value,
+			         slow_timeout_ms * 1000, 1000);
+
+	if (out_value)
+		*out_value = reg_value;
 
 	return ret;
 }
diff --git a/drivers/gpu/drm/i915/intel_uncore.h b/drivers/gpu/drm/i915/intel_uncore.h
index 9ce079b5dd0d..bed019ef000f 100644
--- a/drivers/gpu/drm/i915/intel_uncore.h
+++ b/drivers/gpu/drm/i915/intel_uncore.h
@@ -163,11 +163,23 @@ void intel_uncore_forcewake_put__locked(struct drm_i915_private *dev_priv,
 void intel_uncore_forcewake_user_get(struct drm_i915_private *dev_priv);
 void intel_uncore_forcewake_user_put(struct drm_i915_private *dev_priv);
 
+int __intel_wait_for_register(struct drm_i915_private *dev_priv,
+			      i915_reg_t reg,
+			      u32 mask,
+			      u32 value,
+			      unsigned int fast_timeout_us,
+			      unsigned int slow_timeout_ms,
+			      u32 *out_value);
+static inline
 int intel_wait_for_register(struct drm_i915_private *dev_priv,
 			    i915_reg_t reg,
 			    u32 mask,
 			    u32 value,
-			    unsigned int timeout_ms);
+			    unsigned int timeout_ms)
+{
+	return __intel_wait_for_register(dev_priv, reg, mask, value, 2,
+					 timeout_ms, NULL);
+}
 int __intel_wait_for_register_fw(struct drm_i915_private *dev_priv,
 				 i915_reg_t reg,
 				 u32 mask,
-- 
2.15.0.531.g2ccb3012c9-goog