From f7096d40eea84d32eb1e3b0f2b4407167aae9a83 Mon Sep 17 00:00:00 2001
From: Chris Wilson <chris@chris-wilson.co.uk>
Date: Fri, 1 Dec 2017 12:20:11 +0000
Subject: [PATCH] drm/i915: Sleep and retry a GPU reset if at first we don't succeed
Git-commit: f7096d40eea84d32eb1e3b0f2b4407167aae9a83
Patch-mainline: v4.16-rc1
References: FATE#322643 bsc#1055900

As we declare the GPU wedged if the reset fails, such a failure is quite
terminal. Before taking that drastic action, let's sleep first and try
active, in the hope that the hardware has quietened down and is then
able to reset. After a few such attempts, it is fair to say that the HW
is truly wedged.

V2: Always print the failure message now, we precheck whether resets are
disabled.

References: https://bugs.freedesktop.org/show_bug.cgi?id=104007
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171201122011.16841-1-chris@chris-wilson.co.uk
Reviewed-by: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/gpu/drm/i915/i915_drv.c |   20 +++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)

--- a/drivers/gpu/drm/i915/i915_drv.c
+++ b/drivers/gpu/drm/i915/i915_drv.c
@@ -1877,7 +1877,9 @@ void i915_reset(struct drm_i915_private
 {
 	struct i915_gpu_error *error = &i915->gpu_error;
 	int ret;
+	int i;
 
+	might_sleep();
 	lockdep_assert_held(&i915->drm.struct_mutex);
 	GEM_BUG_ON(!test_bit(I915_RESET_BACKOFF, &error->flags));
 
@@ -1900,12 +1902,20 @@ void i915_reset(struct drm_i915_private
 		goto error;
 	}
 
-	ret = intel_gpu_reset(i915, ALL_ENGINES);
+	if (!intel_has_gpu_reset(i915)) {
+		DRM_DEBUG_DRIVER("GPU reset disabled\n");
+		goto error;
+	}
+
+	for (i = 0; i < 3; i++) {
+		ret = intel_gpu_reset(i915, ALL_ENGINES);
+		if (ret == 0)
+			break;
+
+		msleep(100);
+	}
 	if (ret) {
-		if (ret != -ENODEV)
-			DRM_ERROR("Failed to reset chip: %i\n", ret);
-		else
-			DRM_DEBUG_DRIVER("GPU reset disabled\n");
+		dev_err(i915->drm.dev, "Failed to reset chip\n");
 		goto error;
 	}