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

Mallesh, Koujalagi
2026-03-30T13:40:50Z

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.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.