[PATCH] drm/amdgpu: try again kiq access if not in IRQ(v2)

[Monk Liu]

sometimes GPU is switched to other VFs and won't swich
back soon, so the kiq reg access will not signal within
a short period, instead of busy waiting a long time(MAX_KEQ_REG_WAIT)
and returning TMO we can istead sleep 5ms and try again
later (non irq context)

And since the waiting in kiq_r/weg is busy wait, so MAX_KIQ_REG_WAIT
shouldn't set to a long time, set it to 10ms is more appropriate.

if gpu already in reset state, don't retry the KIQ reg access
otherwise it would always hang because KIQ was already die usually.

v2:
replace schedule() with msleep() for the wait

Change-Id: I8fc807ce85a8d30d2b50153f3f3a6eda344ef994
Signed-off-by: Monk Liu <Monk.Liu at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_virt.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_virt.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_virt.c
index b832651..1672f5b 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_virt.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_virt.c
@@ -22,7 +22,7 @@
  */
 
 #include "amdgpu.h"
-#define MAX_KIQ_REG_WAIT	100000000 /* in usecs */
+#define MAX_KIQ_REG_WAIT	10000 /* in usecs, 10ms */
 
 uint64_t amdgpu_csa_vaddr(struct amdgpu_device *adev)
 {
@@ -152,9 +152,14 @@ uint32_t amdgpu_virt_kiq_rreg(struct amdgpu_device *adev, uint32_t reg)
 	amdgpu_ring_commit(ring);
 	spin_unlock_irqrestore(&kiq->ring_lock, flags);
 
+retry_read:
 	r = amdgpu_fence_wait_polling(ring, seq, MAX_KIQ_REG_WAIT);
 	if (r < 1) {
 		DRM_ERROR("wait for kiq fence error: %ld\n", r);
+		if (!in_interrupt() && !adev->in_gpu_reset) {
+			msleep(5);
+			goto retry_read;
+		}
 		return ~0;
 	}
 	val = adev->wb.wb[adev->virt.reg_val_offs];
@@ -179,9 +184,15 @@ void amdgpu_virt_kiq_wreg(struct amdgpu_device *adev, uint32_t reg, uint32_t v)
 	amdgpu_ring_commit(ring);
 	spin_unlock_irqrestore(&kiq->ring_lock, flags);
 
+retry_write:
 	r = amdgpu_fence_wait_polling(ring, seq, MAX_KIQ_REG_WAIT);
-	if (r < 1)
+	if (r < 1) {
 		DRM_ERROR("wait for kiq fence error: %ld\n", r);
+		if (!in_interrupt() && !adev->in_gpu_reset) {
+			msleep(5);
+			goto retry_write;
+		}
+	}
 }
 
 /**
-- 
2.7.4