drm/i915: Add wait_for_us

This is for callers who want micro-second precision but are not
waiting from the atomic context.

v2:
  * Fix atomic waits. (Dave Gordon)
  * Use USEC_PER_SEC and USEC_PER_MSEC. (Chris Wilson)

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Dave Gordon <david.s.gordon@intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>

drivers/gpu/drm/i915/intel_dp.c

@@ -1792,11 +1792,11 @@ static void wait_panel_status(struct intel_dp *intel_dp,
 			I915_READ(pp_stat_reg),
 			I915_READ(pp_ctrl_reg));
 
-	if (_wait_for((I915_READ(pp_stat_reg) & mask) == value, 5000, 10)) {
+	if (_wait_for((I915_READ(pp_stat_reg) & mask) == value,
+		      5 * USEC_PER_SEC, 10 * USEC_PER_MSEC))
 		DRM_ERROR("Panel status timeout: status %08x control %08x\n",
 				I915_READ(pp_stat_reg),
 				I915_READ(pp_ctrl_reg));
-	}
 
 	DRM_DEBUG_KMS("Wait complete\n");
 }

drivers/gpu/drm/i915/intel_drv.h

@@ -45,8 +45,8 @@
  * 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, MS, W) ({ \
-	unsigned long timeout__ = jiffies + msecs_to_jiffies(MS) + 1;	\
+#define _wait_for(COND, US, W) ({ \
+	unsigned long timeout__ = jiffies + usecs_to_jiffies(US) + 1;	\
 	int ret__ = 0;							\
 	while (!(COND)) {						\
 		if (time_after(jiffies, timeout__)) {			\
@@ -55,18 +55,19 @@
 			break;						\
 		}							\
 		if ((W) && drm_can_sleep()) {				\
-			usleep_range((W)*1000, (W)*2000);		\
+			usleep_range((W), (W)*2);			\
 		} else {						\
 			cpu_relax();					\
 		}							\
 	}								\
 	ret__;								\
 })
 
-#define wait_for(COND, MS) _wait_for(COND, MS, 1)
-#define wait_for_atomic(COND, MS) _wait_for(COND, MS, 0)
-#define wait_for_atomic_us(COND, US) _wait_for((COND), \
-					       DIV_ROUND_UP((US), 1000), 0)
+#define wait_for(COND, MS)	  	_wait_for((COND), (MS) * 1000, 1000)
+#define wait_for_us(COND, US)	  	_wait_for((COND), (US), 1)
+
+#define wait_for_atomic(COND, MS) 	_wait_for((COND), (MS) * 1000, 0)
+#define wait_for_atomic_us(COND, US)	_wait_for((COND), (US), 0)
 
 #define KHz(x) (1000 * (x))
 #define MHz(x) KHz(1000 * (x))

drivers/gpu/drm/i915/intel_psr.c

@@ -507,7 +507,8 @@ static void hsw_psr_disable(struct intel_dp *intel_dp)
 
 		/* Wait till PSR is idle */
 		if (_wait_for((I915_READ(EDP_PSR_STATUS_CTL) &
-			       EDP_PSR_STATUS_STATE_MASK) == 0, 2000, 10))
+			       EDP_PSR_STATUS_STATE_MASK) == 0,
+			       2 * USEC_PER_SEC, 10 * USEC_PER_MSEC))
 			DRM_ERROR("Timed out waiting for PSR Idle State\n");
 
 		dev_priv->psr.active = false;