Re: [PATCH v2 5/5] drm/xe/debugfs: Add interface to trigger power management unit error handler

[Mallesh, Koujalagi]

On 30-03-2026 10:25 am, Tauro, Riana wrote:

On 3/18/2026 12:10 PM, Mallesh Koujalagi wrote:
Add a debugfs interface to manually trigger power management unit error
handler for testing cold reset recovery paths. This is useful for
validating the error recovery mechanism.

The new debugfs entry 'trigger_punit_error' is located at:
   /sys/kernel/debug/dri/N/trigger_punit_error

Reading the file displays usage instructions. Writing '1' invokes
xe_punit_error_handler(), which marks the device as wedged with
DRM_WEDGE_RECOVERY_COLD_RESET method and sends a uevent to userspace
indicating that a complete device power cycle is required for recovery.

Writing '0' or any other false value has no effect.

This interface is intended for development, testing, and validation
of power management unit error recovery code.

Would fault injection be more appropriate here?

Here we need a deterministic way to invoke the punit error handler to 
test the cold-reset

recovery flow end-to-end. Using debugfs interface, we directly triggers 
wedge/reset status via a debugfs write

rather than using fault injection.


Thanks,

-/Mallesh


Thanks
Riana

Signed-off-by: Mallesh Koujalagi <mallesh.koujal...@intel.com>
---
  drivers/gpu/drm/xe/xe_debugfs.c | 38 +++++++++++++++++++++++++++++++++
  1 file changed, 38 insertions(+)

diff --git a/drivers/gpu/drm/xe/xe_debugfs.c 
b/drivers/gpu/drm/xe/xe_debugfs.c
index 844cfafe1ec7..390bbed9c1af 100644
--- a/drivers/gpu/drm/xe/xe_debugfs.c
+++ b/drivers/gpu/drm/xe/xe_debugfs.c
@@ -18,6 +18,7 @@
  #include "xe_gt_debugfs.h"
  #include "xe_gt_printk.h"
  #include "xe_guc_ads.h"
+#include "xe_hw_error.h"
  #include "xe_mmio.h"
  #include "xe_pm.h"
  #include "xe_psmi.h"
@@ -509,6 +510,40 @@ static const struct file_operations 
disable_late_binding_fops = {
      .write = disable_late_binding_set,
  };
  +static ssize_t trigger_punit_error_show(struct file *f, char 
__user *ubuf,
+                    size_t size, loff_t *pos)
+{
+    const char *msg = "Write 1 to trigger power management unit 
error handler\n";
+
+    return simple_read_from_buffer(ubuf, size, pos, msg, strlen(msg));
+}
+
+static ssize_t trigger_punit_error_set(struct file *f,
+                       const char __user *ubuf,
+                       size_t size, loff_t *pos)
+{
+    struct xe_device *xe = file_inode(f)->i_private;
+    bool trigger;
+    ssize_t ret;
+
+    ret = kstrtobool_from_user(ubuf, size, &trigger);
+    if (ret)
+        return ret;
+
+    if (trigger) {
+        xe_punit_error_handler(xe);
+        drm_info(&xe->drm, "PMU error handler triggered via 
debugfs\n");
+    }
+
+    return size;
+}
+
+static const struct file_operations trigger_punit_error_fops = {
+    .owner = THIS_MODULE,
+    .read = trigger_punit_error_show,
+    .write = trigger_punit_error_set,
+};
+
  void xe_debugfs_register(struct xe_device *xe)
  {
      struct ttm_device *bdev = &xe->ttm;
@@ -550,6 +585,9 @@ void xe_debugfs_register(struct xe_device *xe)
      debugfs_create_file("disable_late_binding", 0600, root, xe,
                  &disable_late_binding_fops);
  +    debugfs_create_file("trigger_punit_error", 0600, root, xe,
+                &trigger_punit_error_fops);
+
      /*
       * Don't expose page reclaim configuration file if not 
supported by the
       * hardware initially.