drm/i915: Add more control to wait_for routines

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
Changes in v3:
- Rebased on drm-intel-next-queued and the new Wmin/max _wait_for
- Removed msleep option
Changes in v4:
- Removed ; for OP in _wait_for (Chris)
- Moved reg_value definition above ret (Chris)
Changes in v4:
- checkpatch whitespace fix
Changes in v5:
- None
Changes in v6:
- None
Suggested-by: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Sean Paul <seanpaul@chromium.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20180108195545.218615-3-seanpaul@chromium.org

drivers/gpu/drm/i915/intel_drv.h

@@ -41,20 +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
- * 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.
+ * Macro to help avoid open coding check/wait/timeout patterns. 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, Wmin, Wmax) ({ \
+#define __wait_for(OP, COND, US, Wmin, Wmax) ({ \
 	unsigned long timeout__ = jiffies + usecs_to_jiffies(US) + 1;	\
 	long wait__ = (Wmin); /* recommended min for usleep is 10 us */	\
 	int ret__;							\
 	might_sleep();							\
 	for (;;) {							\
 		bool expired__ = time_after(jiffies, timeout__);	\
+		OP;							\
 		if (COND) {						\
 			ret__ = 0;					\
 			break;						\
@@ -70,7 +71,9 @@
 	ret__;								\
 })
 
-#define wait_for(COND, MS)	_wait_for((COND), (MS) * 1000, 10, 1000)
+#define _wait_for(COND, US, Wmin, Wmax)	__wait_for(, (COND), (US), (Wmin), \
+						   (Wmax))
+#define wait_for(COND, MS)		_wait_for((COND), (MS) * 1000, 10, 1000)
 
 /* If CONFIG_PREEMPT_COUNT is disabled, in_atomic() always reports false. */
 #if defined(CONFIG_DRM_I915_DEBUG) && defined(CONFIG_PREEMPT_COUNT)

drivers/gpu/drm/i915/intel_uncore.c

@@ -1767,12 +1767,14 @@ 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 ::
@@ -1783,14 +1785,17 @@ 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);
+	u32 reg_value;
 	int ret;
 
 	might_sleep();
@@ -1800,14 +1805,18 @@ 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, 10, 1000);
+
+	if (out_value)
+		*out_value = reg_value;
 
 	return ret;
 }

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,