[Intel-gfx] [PATCH v2] drm/i915: Add fault injection support

[Imre Deak]

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

CC: Chris Wilson <chris at chris-wilson.co.uk>
Signed-off-by: Imre Deak <imre.deak at intel.com>
---
 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 b1dbf1b..65be671 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_fault(I915_FAULT_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_fault(I915_FAULT_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_fault(I915_FAULT_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_fault(I915_FAULT_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 f62b6d1..33bcc6e 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_FAULT_INIT_EARLY	1
+#define I915_FAULT_INIT_MMIO	2
+#define I915_FAULT_INIT_HW	4
+#define I915_FAULT_INIT_MODESET	8
+
+static inline bool i915_inject_fault(unsigned int fault_mask)
+{
+	if (i915.inject_fault & fault_mask) {
+		DRM_DEBUG_DRIVER("Injecting fault %08x\n", fault_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..d96c2c0 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_fault = 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_fault, i915.inject_fault, uint, 0600);
+MODULE_PARM_DESC(inject_fault,
+	"Force an error at selected points (0:disabled, 1:INIT_EARLY, 2:INIT_MMIO, 4:INIT_HW)");
diff --git a/drivers/gpu/drm/i915/i915_params.h b/drivers/gpu/drm/i915/i915_params.h
index bd5026b..2989a48 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_fault;
 };
 
 extern struct i915_params i915 __read_mostly;
-- 
2.5.0