drm/i915: Ensure that while(INREG()) are bounded (v2)
Add a new macro, wait_for, to simplify the act of waiting on a register
to change state. wait_for() takes three arguments, the condition to
inspect on every loop, the maximum amount of time to wait and whether to
yield the cpu for a length of time after each check.
v2: Upgrade failure messages to DRM_ERROR on the suggestion of
Eric Anholt. We do not expect to hit these conditions as they reflect
programming errors, so if we do we want to be notified.
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Eric Anholt <eric@anholt.net>
diff --git a/drivers/gpu/drm/i915/intel_crt.c b/drivers/gpu/drm/i915/intel_crt.c
index cfcf854..c43176d 100644
--- a/drivers/gpu/drm/i915/intel_crt.c
+++ b/drivers/gpu/drm/i915/intel_crt.c
@@ -185,8 +185,9 @@
DRM_DEBUG_KMS("pch crt adpa 0x%x", adpa);
I915_WRITE(PCH_ADPA, adpa);
- while ((I915_READ(PCH_ADPA) & ADPA_CRT_HOTPLUG_FORCE_TRIGGER) != 0)
- ;
+ if (wait_for((I915_READ(PCH_ADPA) & ADPA_CRT_HOTPLUG_FORCE_TRIGGER) == 0,
+ 1000, 1))
+ DRM_ERROR("timed out waiting for FORCE_TRIGGER");
if (HAS_PCH_CPT(dev)) {
I915_WRITE(PCH_ADPA, temp);
@@ -237,17 +238,13 @@
hotplug_en |= CRT_HOTPLUG_FORCE_DETECT;
for (i = 0; i < tries ; i++) {
- unsigned long timeout;
/* turn on the FORCE_DETECT */
I915_WRITE(PORT_HOTPLUG_EN, hotplug_en);
- timeout = jiffies + msecs_to_jiffies(1000);
/* wait for FORCE_DETECT to go off */
- do {
- if (!(I915_READ(PORT_HOTPLUG_EN) &
- CRT_HOTPLUG_FORCE_DETECT))
- break;
- msleep(1);
- } while (time_after(timeout, jiffies));
+ if (wait_for((I915_READ(PORT_HOTPLUG_EN) &
+ CRT_HOTPLUG_FORCE_DETECT) == 0,
+ 1000, 1))
+ DRM_ERROR("timed out waiting for FORCE_DETECT to go off");
}
stat = I915_READ(PORT_HOTPLUG_STAT);