drm/radeon: apply Murphy's law to the kms irq code v3

1. It is really dangerous to have more than one
   spinlock protecting the same information.

2. radeon_irq_set sometimes wasn't called with lock
   protection, so it can happen that more than one
   CPU would tamper with the irq regs at the same
   time.

3. The pm.gui_idle variable was assuming that the 3D
   engine wasn't becoming idle between testing the
   register and setting the variable. So just remove
   it and test the register directly.

v2: Also handle the hpd irq code the same way.
v3: Rename hpd parameter for clarification.

Signed-off-by: Christian Koenig <christian.koenig@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>

1 files changed, 9 insertions, 3 deletions

diff --git a/drivers/gpu/drm/radeon/radeon_kms.c b/drivers/gpu/drm/radeon/radeon_kms.c
index 5c58d7d90cb2..18b81d63ee7b 100644
--- a/drivers/gpu/drm/radeon/radeon_kms.c
+++ b/drivers/gpu/drm/radeon/radeon_kms.c
@@ -382,29 +382,35 @@ u32 radeon_get_vblank_counter_kms(struct drm_device *dev, int crtc)
 int radeon_enable_vblank_kms(struct drm_device *dev, int crtc)
 {
         struct radeon_device *rdev = dev->dev_private;
+        unsigned long irqflags;
+        int r;
 
         if (crtc < 0 || crtc >= rdev->num_crtc) {
                 DRM_ERROR("Invalid crtc %d\n", crtc);
                 return -EINVAL;
         }
 
+        spin_lock_irqsave(&rdev->irq.lock, irqflags);
         rdev->irq.crtc_vblank_int[crtc] = true;
-
-        return radeon_irq_set(rdev);
+        r = radeon_irq_set(rdev);
+        spin_unlock_irqrestore(&rdev->irq.lock, irqflags);
+        return r;
 }
 
 void radeon_disable_vblank_kms(struct drm_device *dev, int crtc)
 {
         struct radeon_device *rdev = dev->dev_private;
+        unsigned long irqflags;
 
         if (crtc < 0 || crtc >= rdev->num_crtc) {
                 DRM_ERROR("Invalid crtc %d\n", crtc);
                 return;
         }
 
+        spin_lock_irqsave(&rdev->irq.lock, irqflags);
         rdev->irq.crtc_vblank_int[crtc] = false;
-
         radeon_irq_set(rdev);
+        spin_unlock_irqrestore(&rdev->irq.lock, irqflags);
 }
 
 int radeon_get_vblank_timestamp_kms(struct drm_device *dev, int crtc,