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

Tauro, Riana
2026-03-30T04:56:09Z

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?

Thanks
Riana

> Signed-off-by: Mallesh Koujalagi <mallesh.koujalagi@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.