Re: [PATCH 4/4] drm/i915/reset: Add "display_reset_count" debugfs file

[Jani Nikula <jani.nikula@intel.com>]

On Fri, 10 Apr 2026, Ville Syrjala <ville.syrjala@linux.intel.com> wrote:
> From: Ville Syrjälä <ville.syrjala@linux.intel.com>
>
> Expose the number of display resets performed in a new
> "display_reset_count" debugfs file. kms_busy can use this to
> confirm that the kernel actually took the full display reset path.
>
> Cc: Jani Nikula <jani.nikula@intel.com>
> Cc: Jouni Högander <jouni.hogander@intel.com>
> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
> ---
>  drivers/gpu/drm/i915/display/intel_display_core.h    |  4 ++++
>  drivers/gpu/drm/i915/display/intel_display_debugfs.c |  2 ++
>  drivers/gpu/drm/i915/display/intel_display_reset.c   | 10 ++++++++++
>  drivers/gpu/drm/i915/display/intel_display_reset.h   |  2 ++
>  drivers/gpu/drm/xe/Makefile                          |  1 +
>  5 files changed, 19 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_display_core.h b/drivers/gpu/drm/i915/display/intel_display_core.h
> index 9e77003addd0..38535d1056d1 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_core.h
> +++ b/drivers/gpu/drm/i915/display/intel_display_core.h
> @@ -556,6 +556,10 @@ struct intel_display {
>  		unsigned long mask;
>  	} quirks;
>  
> +	struct {
> +		u32 count;
> +	} reset;
> +
>  	struct {
>  		/* restore state for suspend/resume and display reset */
>  		struct drm_atomic_state *modeset_state;
> diff --git a/drivers/gpu/drm/i915/display/intel_display_debugfs.c b/drivers/gpu/drm/i915/display/intel_display_debugfs.c
> index f244a2b5d139..81bef000a4e3 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_debugfs.c
> +++ b/drivers/gpu/drm/i915/display/intel_display_debugfs.c
> @@ -27,6 +27,7 @@
>  #include "intel_display_power.h"
>  #include "intel_display_power_well.h"
>  #include "intel_display_regs.h"
> +#include "intel_display_reset.h"
>  #include "intel_display_rpm.h"
>  #include "intel_display_types.h"
>  #include "intel_dmc.h"
> @@ -838,6 +839,7 @@ void intel_display_debugfs_register(struct intel_display *display)
>  
>  	intel_bios_debugfs_register(display);
>  	intel_cdclk_debugfs_register(display);
> +	intel_display_reset_debugfs_register(display);
>  	intel_dmc_debugfs_register(display);
>  	intel_dp_test_debugfs_register(display);
>  	intel_fbc_debugfs_register(display);
> diff --git a/drivers/gpu/drm/i915/display/intel_display_reset.c b/drivers/gpu/drm/i915/display/intel_display_reset.c
> index ca15dc18ef0f..79c2e77ca137 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_reset.c
> +++ b/drivers/gpu/drm/i915/display/intel_display_reset.c
> @@ -3,6 +3,8 @@
>   * Copyright © 2023 Intel Corporation
>   */
>  
> +#include <linux/debugfs.h>
> +
>  #include <drm/drm_atomic_helper.h>
>  #include <drm/drm_print.h>
>  
> @@ -66,6 +68,7 @@ void intel_display_reset_prepare(struct intel_display *display)
>  		return;
>  	}
>  
> +	display->reset.count++;
>  	display->restore.modeset_state = state;
>  	state->acquire_ctx = ctx;
>  }
> @@ -114,3 +117,10 @@ void intel_display_reset_finish(struct intel_display *display, bool test_only)
>  	drm_modeset_acquire_fini(ctx);
>  	mutex_unlock(&display->drm->mode_config.mutex);
>  }
> +
> +void intel_display_reset_debugfs_register(struct intel_display *display)
> +{
> +	debugfs_create_u32("display_reset_count", 0400,
> +			   display->drm->debugfs_root,
> +			   &display->reset.count);

I'm wondering about the names of the debugfs files. We've used the i915_
prefix so far, but it's obviously misleading nowadays. I've started
using intel_ in some places.

I primarily worry about the potential clash with drm core debugfs files,
which leads to failures to create the file, and clash with other
drivers, where the files are created all right, but the contents differ
driver to driver.

*shrug*

Reviewed-by: Jani Nikula <jani.nikula@intel.com>


> +}
> diff --git a/drivers/gpu/drm/i915/display/intel_display_reset.h b/drivers/gpu/drm/i915/display/intel_display_reset.h
> index a8aa7729d33f..b88c330a3441 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_reset.h
> +++ b/drivers/gpu/drm/i915/display/intel_display_reset.h
> @@ -15,4 +15,6 @@ bool intel_display_reset_test(struct intel_display *display);
>  void intel_display_reset_prepare(struct intel_display *display);
>  void intel_display_reset_finish(struct intel_display *display, bool test_only);
>  
> +void intel_display_reset_debugfs_register(struct intel_display *display);
> +
>  #endif /* __INTEL_RESET_H__ */
> diff --git a/drivers/gpu/drm/xe/Makefile b/drivers/gpu/drm/xe/Makefile
> index 110fef511fe2..1a85dfe457f0 100644
> --- a/drivers/gpu/drm/xe/Makefile
> +++ b/drivers/gpu/drm/xe/Makefile
> @@ -262,6 +262,7 @@ xe-$(CONFIG_DRM_XE_DISPLAY) += \
>  	i915-display/intel_display_power.o \
>  	i915-display/intel_display_power_map.o \
>  	i915-display/intel_display_power_well.o \
> +	i915-display/intel_display_reset.o \
>  	i915-display/intel_display_rpm.o \
>  	i915-display/intel_display_rps.o \
>  	i915-display/intel_display_trace.o \

-- 
Jani Nikula, Intel