drm/i915: Add fault injection support

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)
- Use a counter instead of a mask to identify the failure point (Daniel)
- Mark the module option as _unsafe and keep i915_params ordered (Joonas)
v4:
- Rebase on latest -nightly
v5:
- Use DRM_INFO instead of DRM_DEBUG_DRIVER, making it clearer in CI reports
  that a following error message is expected (IRC r-b from Chris on v5)

CC: Chris Wilson <chris@chris-wilson.co.uk>
CC: Daniel Vetter <daniel.vetter@ffwll.ch>
CC: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Signed-off-by: Imre Deak <imre.deak@intel.com>
Reviewed-by: Chris Wilson <chris@chris-wilson.co.uk>

diff --git a/drivers/gpu/drm/i915/i915_dma.c b/drivers/gpu/drm/i915/i915_dma.c
index 7466e739887de47903f55a1d01746476bf88b408..68592b0de874194024db27aacda0baafbe64ce9f 100644 (file)
--- a/drivers/gpu/drm/i915/i915_dma.c
+++ b/drivers/gpu/drm/i915/i915_dma.c
@@ -50,6 +50,21 @@
 #include <linux/pm_runtime.h>
 #include <linux/oom.h>
 
+static unsigned int i915_load_fail_count;
+
+bool __i915_inject_load_failure(const char *func, int line)
+{
+       if (i915_load_fail_count >= i915.inject_load_failure)
+               return false;
+
+       if (++i915_load_fail_count == i915.inject_load_failure) {
+               DRM_INFO("Injecting failure at checkpoint %u [%s:%d]\n",
+                        i915.inject_load_failure, func, line);
+               return true;
+       }
+
+       return false;
+}
 
 static int i915_getparam(struct drm_device *dev, void *data,
                         struct drm_file *file_priv)
@@ -370,6 +385,9 @@ 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())
+               return -ENODEV;
+
        ret = intel_bios_init(dev_priv);
        if (ret)
                DRM_INFO("failed to find VBIOS tables\n");
@@ -951,6 +969,9 @@ 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())
+               return -ENODEV;
+
        dev_priv->dev = dev;
 
        /* Setup the write-once "constant" device info */
@@ -1065,6 +1086,9 @@ 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())
+               return -ENODEV;
+
        if (i915_get_bridge_dev(dev))
                return -EIO;
 
@@ -1108,6 +1132,9 @@ static int i915_driver_init_hw(struct drm_i915_private *dev_priv)
        uint32_t aperture_size;
        int ret;
 
+       if (i915_inject_load_failure())
+               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 e6d4b1ce130e3265817614af665434bd1d21c48a..00c41a4bde2aabb3fa2cf54f5c606bfbd9c6d8fc 100644 (file)
--- a/drivers/gpu/drm/i915/i915_drv.h
+++ b/drivers/gpu/drm/i915/i915_drv.h
@@ -98,6 +98,10 @@
 #define I915_STATE_WARN_ON(x)                                          \
        I915_STATE_WARN((x), "%s", "WARN_ON(" __stringify(x) ")")
 
+bool __i915_inject_load_failure(const char *func, int line);
+#define i915_inject_load_failure() \
+       __i915_inject_load_failure(__func__, __LINE__)
+
 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 97691f1f679cf0f0204b920fe12b153f6f4d9146..1779f02e6df8fd3c406034b4bad1e3f9577e47b2 100644 (file)
--- a/drivers/gpu/drm/i915/i915_params.c
+++ b/drivers/gpu/drm/i915/i915_params.c
@@ -57,6 +57,7 @@ struct i915_params i915 __read_mostly = {
        .enable_guc_submission = false,
        .guc_log_level = -1,
        .enable_dp_mst = true,
+       .inject_load_failure = 0,
 };
 
 module_param_named(modeset, i915.modeset, int, 0400);
@@ -206,3 +207,6 @@ MODULE_PARM_DESC(guc_log_level,
 module_param_named_unsafe(enable_dp_mst, i915.enable_dp_mst, bool, 0600);
 MODULE_PARM_DESC(enable_dp_mst,
        "Enable multi-stream transport (MST) for new DisplayPort sinks. (default: true)");
+module_param_named_unsafe(inject_load_failure, i915.inject_load_failure, uint, 0400);
+MODULE_PARM_DESC(inject_load_failure,
+       "Force an error after a number of failure check points (0:disabled (default), N:force failure at the Nth failure check point)");

diff --git a/drivers/gpu/drm/i915/i915_params.h b/drivers/gpu/drm/i915/i915_params.h
index 87153b0199cd2b604974a771380d61f2e30706c4..02bc27804291296a9303088af9c6cc082f2299fd 100644 (file)
--- a/drivers/gpu/drm/i915/i915_params.h
+++ b/drivers/gpu/drm/i915/i915_params.h
@@ -49,6 +49,7 @@ struct i915_params {
        int use_mmio_flip;
        int mmio_debug;
        int edp_vswing;
+       unsigned int inject_load_failure;
        /* leave bools at the end to not create holes */
        bool enable_hangcheck;
        bool fastboot;