[PATCH v3] drm/i915: Add fault injection support

[Imre Deak <imre.deak@intel.com>]

Add support for forcing an error at selected places in the driver. As an
example add 4 options to fail during driver loading.

Requested by Chris.

v2:
- Add fault point for modeset initialization
- Print debug message when injecting an error
v3:
- Rename inject_fault to inject_load_failure, rename the related macros
  and helper accordingly (Chris)

CC: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: Imre Deak <imre.deak@intel.com>
---

[This depends on
 https://lists.freedesktop.org/archives/intel-gfx/2016-March/089597.html]

 drivers/gpu/drm/i915/i915_dma.c    | 12 ++++++++++++
 drivers/gpu/drm/i915/i915_drv.h    | 16 ++++++++++++++++
 drivers/gpu/drm/i915/i915_params.c |  5 +++++
 drivers/gpu/drm/i915/i915_params.h |  1 +
 4 files changed, 34 insertions(+)

diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
index a5121cd..7490307 100644
--- a/drivers/gpu/drm/i915/i915_dma.c
+++ b/drivers/gpu/drm/i915/i915_dma.c
@@ -370,6 +370,9 @@ static int i915_load_modeset_init(struct drm_device *dev)
 	struct drm_i915_private *dev_priv = dev->dev_private;
 	int ret;
 
+	if (i915_inject_load_failure(I915_FAIL_INIT_MODESET))
+		return -ENODEV;
+
 	ret = intel_bios_init(dev_priv);
 	if (ret)
 		DRM_INFO("failed to find VBIOS tables\n");
@@ -950,6 +953,9 @@ static int i915_driver_init_early(struct drm_i915_private *dev_priv,
 	struct intel_device_info *device_info;
 	int ret = 0;
 
+	if (i915_inject_load_failure(I915_FAIL_INIT_EARLY))
+		return -ENODEV;
+
 	dev_priv->dev = dev;
 
 	/* Setup the write-once "constant" device info */
@@ -1064,6 +1070,9 @@ static int i915_driver_init_mmio(struct drm_i915_private *dev_priv)
 	struct drm_device *dev = dev_priv->dev;
 	int ret;
 
+	if (i915_inject_load_failure(I915_FAIL_INIT_MMIO))
+		return -ENODEV;
+
 	if (i915_get_bridge_dev(dev))
 		return -EIO;
 
@@ -1107,6 +1116,9 @@ static int i915_driver_init_hw(struct drm_i915_private *dev_priv)
 	uint32_t aperture_size;
 	int ret;
 
+	if (i915_inject_load_failure(I915_FAIL_INIT_HW))
+		return -ENODEV;
+
 	intel_device_info_runtime_init(dev);
 
 	ret = i915_gem_gtt_init(dev);
diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
index 25274e1..e2d21d5 100644
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -98,6 +98,22 @@
 #define I915_STATE_WARN_ON(x)						\
 	I915_STATE_WARN((x), "%s", "WARN_ON(" __stringify(x) ")")
 
+#define I915_FAIL_INIT_EARLY	BIT(0)
+#define I915_FAIL_INIT_MMIO	BIT(1)
+#define I915_FAIL_INIT_HW	BIT(2)
+#define I915_FAIL_INIT_MODESET	BIT(3)
+
+static inline bool i915_inject_load_failure(unsigned int fail_mask)
+{
+	if (i915.inject_load_failure & fail_mask) {
+		DRM_DEBUG_DRIVER("Injecting failure %08x\n", fail_mask);
+
+		return true;
+	}
+
+	return false;
+}
+
 static inline const char *yesno(bool v)
 {
 	return v ? "yes" : "no";
diff --git a/drivers/gpu/drm/i915/i915_params.c b/drivers/gpu/drm/i915/i915_params.c
index 278c9c4..4faeeed 100644
--- a/drivers/gpu/drm/i915/i915_params.c
+++ b/drivers/gpu/drm/i915/i915_params.c
@@ -56,6 +56,7 @@ struct i915_params i915 __read_mostly = {
 	.edp_vswing = 0,
 	.enable_guc_submission = false,
 	.guc_log_level = -1,
+	.inject_load_failure = 0,
 };
 
 module_param_named(modeset, i915.modeset, int, 0400);
@@ -201,3 +202,7 @@ MODULE_PARM_DESC(enable_guc_submission, "Enable GuC submission (default:false)")
 module_param_named(guc_log_level, i915.guc_log_level, int, 0400);
 MODULE_PARM_DESC(guc_log_level,
 	"GuC firmware logging level (-1:disabled (default), 0-3:enabled)");
+
+module_param_named(inject_load_failure, i915.inject_load_failure, uint, 0600);
+MODULE_PARM_DESC(inject_load_failure,
+	"Force an error at selected points (0:disabled, 0x1:INIT_EARLY, 0x2:INIT_MMIO, 0x4:INIT_HW, 0x8:INIT_MODESET)");
diff --git a/drivers/gpu/drm/i915/i915_params.h b/drivers/gpu/drm/i915/i915_params.h
index bd5026b..b691026 100644
--- a/drivers/gpu/drm/i915/i915_params.h
+++ b/drivers/gpu/drm/i915/i915_params.h
@@ -59,6 +59,7 @@ struct i915_params {
 	bool enable_guc_submission;
 	bool verbose_state_checks;
 	bool nuclear_pageflip;
+	unsigned int inject_load_failure;
 };
 
 extern struct i915_params i915 __read_mostly;
-- 
2.5.0

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