From: Monk Liu <Monk.Liu@amd.com>
Date: Mon, 25 Dec 2017 15:59:30 +0800
Subject: drm/amdgpu: try again kiq access if not in IRQ(v4)
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Git-commit: a22144a58f784265fe8140724a7390443f63ef53
Patch-mainline: v4.17-rc1
References: FATE#326289 FATE#326079 FATE#326049 FATE#322398 FATE#326166

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

v3:
use while loop for the wait repeating
use macros for the sleep period
more description for it

v4:
drop unused variable

Signed-off-by: Monk Liu <Monk.Liu@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com
Reviewed-by: Pixel Ding <Pixel.Ding@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_virt.c |   64 +++++++++++++++++++++++++------
 1 file changed, 53 insertions(+), 11 deletions(-)

--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_virt.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_virt.c
@@ -22,7 +22,9 @@
  */
 
 #include "amdgpu.h"
-#define MAX_KIQ_REG_WAIT	100000000 /* in usecs */
+#define MAX_KIQ_REG_WAIT	5000 /* in usecs, 5ms */
+#define MAX_KIQ_REG_BAILOUT_INTERVAL	5 /* in msecs, 5ms */
+#define MAX_KIQ_REG_TRY 20
 
 uint64_t amdgpu_csa_vaddr(struct amdgpu_device *adev)
 {
@@ -137,9 +139,9 @@ void amdgpu_virt_init_setting(struct amd
 
 uint32_t amdgpu_virt_kiq_rreg(struct amdgpu_device *adev, uint32_t reg)
 {
-	signed long r;
+	signed long r, cnt = 0;
 	unsigned long flags;
-	uint32_t val, seq;
+	uint32_t seq;
 	struct amdgpu_kiq *kiq = &adev->gfx.kiq;
 	struct amdgpu_ring *ring = &kiq->ring;
 
@@ -153,18 +155,36 @@ uint32_t amdgpu_virt_kiq_rreg(struct amd
 	spin_unlock_irqrestore(&kiq->ring_lock, flags);
 
 	r = amdgpu_fence_wait_polling(ring, seq, MAX_KIQ_REG_WAIT);
-	if (r < 1) {
-		DRM_ERROR("wait for kiq fence error: %ld\n", r);
-		return ~0;
+
+	/* don't wait anymore for gpu reset case because this way may
+	 * block gpu_recover() routine forever, e.g. this virt_kiq_rreg
+	 * is triggered in TTM and ttm_bo_lock_delayed_workqueue() will
+	 * never return if we keep waiting in virt_kiq_rreg, which cause
+	 * gpu_recover() hang there.
+	 *
+	 * also don't wait anymore for IRQ context
+	 * */
+	if (r < 1 && (adev->in_gpu_reset || in_interrupt()))
+		goto failed_kiq_read;
+
+	while (r < 1 && cnt++ < MAX_KIQ_REG_TRY) {
+		msleep(MAX_KIQ_REG_BAILOUT_INTERVAL);
+		r = amdgpu_fence_wait_polling(ring, seq, MAX_KIQ_REG_WAIT);
 	}
-	val = adev->wb.wb[adev->virt.reg_val_offs];
 
-	return val;
+	if (cnt > MAX_KIQ_REG_TRY)
+		goto failed_kiq_read;
+
+	return adev->wb.wb[adev->virt.reg_val_offs];
+
+failed_kiq_read:
+	pr_err("failed to read reg:%x\n", reg);
+	return ~0;
 }
 
 void amdgpu_virt_kiq_wreg(struct amdgpu_device *adev, uint32_t reg, uint32_t v)
 {
-	signed long r;
+	signed long r, cnt = 0;
 	unsigned long flags;
 	uint32_t seq;
 	struct amdgpu_kiq *kiq = &adev->gfx.kiq;
@@ -180,8 +200,30 @@ void amdgpu_virt_kiq_wreg(struct amdgpu_
 	spin_unlock_irqrestore(&kiq->ring_lock, flags);
 
 	r = amdgpu_fence_wait_polling(ring, seq, MAX_KIQ_REG_WAIT);
-	if (r < 1)
-		DRM_ERROR("wait for kiq fence error: %ld\n", r);
+
+	/* don't wait anymore for gpu reset case because this way may
+	 * block gpu_recover() routine forever, e.g. this virt_kiq_rreg
+	 * is triggered in TTM and ttm_bo_lock_delayed_workqueue() will
+	 * never return if we keep waiting in virt_kiq_rreg, which cause
+	 * gpu_recover() hang there.
+	 *
+	 * also don't wait anymore for IRQ context
+	 * */
+	if (r < 1 && (adev->in_gpu_reset || in_interrupt()))
+		goto failed_kiq_write;
+
+	while (r < 1 && cnt++ < MAX_KIQ_REG_TRY) {
+		msleep(MAX_KIQ_REG_BAILOUT_INTERVAL);
+		r = amdgpu_fence_wait_polling(ring, seq, MAX_KIQ_REG_WAIT);
+	}
+
+	if (cnt > MAX_KIQ_REG_TRY)
+		goto failed_kiq_write;
+
+	return;
+
+failed_kiq_write:
+	pr_err("failed to write reg:%x\n", reg);
 }
 
 /**