On Mon, Mar 03, 2025 at 01:27:07PM +0200, Jani Nikula wrote:
> Since commit d59cf7bb73f3 ("drm/i915/display: Use dma_fence interfaces
> instead of i915_sw_fence") we don't have anyone waiting on the
> I915_RESET_MODESET bit, and there's no need for its semantics. Instead,
> simply return true from intel_display_reset_prepare() to indicate that
> intel_display_reset_finish() should be called.
>
> Cc: Matt Roper <matthew.d.roper@xxxxxxxxx>
> Signed-off-by: Jani Nikula <jani.nikula@xxxxxxxxx>
Reviewed-by: Matt Roper <matthew.d.roper@xxxxxxxxx>
> ---
> .../drm/i915/display/intel_display_reset.c | 24 +++++++------------
> .../drm/i915/display/intel_display_reset.h | 2 +-
> drivers/gpu/drm/i915/gt/intel_reset.c | 8 ++++---
> drivers/gpu/drm/i915/gt/intel_reset_types.h | 3 +--
> 4 files changed, 15 insertions(+), 22 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/display/intel_display_reset.c b/drivers/gpu/drm/i915/display/intel_display_reset.c
> index 121679b4230f..acc728c75328 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_reset.c
> +++ b/drivers/gpu/drm/i915/display/intel_display_reset.c
> @@ -27,7 +27,8 @@ bool intel_display_reset_test(struct intel_display *display)
> return display->params.force_reset_modeset_test;
> }
>
> -void intel_display_reset_prepare(struct intel_display *display)
> +/* returns true if intel_display_reset_finish() needs to be called */
> +bool intel_display_reset_prepare(struct intel_display *display)
> {
> struct drm_i915_private *dev_priv = to_i915(display->drm);
> struct drm_modeset_acquire_ctx *ctx = &display->restore.reset_ctx;
> @@ -35,17 +36,12 @@ void intel_display_reset_prepare(struct intel_display *display)
> int ret;
>
> if (!HAS_DISPLAY(display))
> - return;
> + return false;
>
> /* reset doesn't touch the display */
> if (!intel_display_reset_test(display) &&
> !gpu_reset_clobbers_display(display))
> - return;
> -
> - /* We have a modeset vs reset deadlock, defensively unbreak it. */
> - set_bit(I915_RESET_MODESET, &to_gt(dev_priv)->reset.flags);
> - smp_mb__after_atomic();
> - wake_up_bit(&to_gt(dev_priv)->reset.flags, I915_RESET_MODESET);
> + return false;
>
> if (atomic_read(&display->restore.pending_fb_pin)) {
> drm_dbg_kms(display->drm,
> @@ -75,7 +71,7 @@ void intel_display_reset_prepare(struct intel_display *display)
> ret = PTR_ERR(state);
> drm_err(display->drm, "Duplicating state failed with %i\n",
> ret);
> - return;
> + return true;
> }
>
> ret = drm_atomic_helper_disable_all(display->drm, ctx);
> @@ -83,11 +79,13 @@ void intel_display_reset_prepare(struct intel_display *display)
> drm_err(display->drm, "Suspending crtc's failed with %i\n",
> ret);
> drm_atomic_state_put(state);
> - return;
> + return true;
> }
>
> display->restore.modeset_state = state;
> state->acquire_ctx = ctx;
> +
> + return true;
> }
>
> void intel_display_reset_finish(struct intel_display *display)
> @@ -100,10 +98,6 @@ void intel_display_reset_finish(struct intel_display *display)
> if (!HAS_DISPLAY(display))
> return;
>
> - /* reset doesn't touch the display */
> - if (!test_bit(I915_RESET_MODESET, &to_gt(i915)->reset.flags))
> - return;
> -
> state = fetch_and_zero(&display->restore.modeset_state);
> if (!state)
> goto unlock;
> @@ -141,6 +135,4 @@ void intel_display_reset_finish(struct intel_display *display)
> drm_modeset_drop_locks(ctx);
> drm_modeset_acquire_fini(ctx);
> mutex_unlock(&display->drm->mode_config.mutex);
> -
> - clear_bit_unlock(I915_RESET_MODESET, &to_gt(i915)->reset.flags);
> }
> diff --git a/drivers/gpu/drm/i915/display/intel_display_reset.h b/drivers/gpu/drm/i915/display/intel_display_reset.h
> index c1dd2e8d0914..311b5af8ca0c 100644
> --- a/drivers/gpu/drm/i915/display/intel_display_reset.h
> +++ b/drivers/gpu/drm/i915/display/intel_display_reset.h
> @@ -11,7 +11,7 @@
> struct intel_display;
>
> bool intel_display_reset_test(struct intel_display *display);
> -void intel_display_reset_prepare(struct intel_display *display);
> +bool intel_display_reset_prepare(struct intel_display *display);
> void intel_display_reset_finish(struct intel_display *display);
>
> #endif /* __INTEL_RESET_H__ */
> diff --git a/drivers/gpu/drm/i915/gt/intel_reset.c b/drivers/gpu/drm/i915/gt/intel_reset.c
> index 835c9081b239..f6c8e4d48b04 100644
> --- a/drivers/gpu/drm/i915/gt/intel_reset.c
> +++ b/drivers/gpu/drm/i915/gt/intel_reset.c
> @@ -1419,12 +1419,14 @@ static void intel_gt_reset_global(struct intel_gt *gt,
> intel_wedge_on_timeout(&w, gt, 60 * HZ) {
> struct drm_i915_private *i915 = gt->i915;
> struct intel_display *display = &i915->display;
> + bool reset_display;
>
> - intel_display_reset_prepare(display);
> + reset_display = intel_display_reset_prepare(display);
>
> intel_gt_reset(gt, engine_mask, reason);
>
> - intel_display_reset_finish(display);
> + if (reset_display)
> + intel_display_reset_finish(display);
> }
>
> if (!test_bit(I915_WEDGED, >->reset.flags))
> @@ -1492,7 +1494,7 @@ void intel_gt_handle_error(struct intel_gt *gt,
> intel_has_reset_engine(gt) && !intel_gt_is_wedged(gt)) {
> local_bh_disable();
> for_each_engine_masked(engine, gt, engine_mask, tmp) {
> - BUILD_BUG_ON(I915_RESET_MODESET >= I915_RESET_ENGINE);
> + BUILD_BUG_ON(I915_RESET_BACKOFF >= I915_RESET_ENGINE);
> if (test_and_set_bit(I915_RESET_ENGINE + engine->id,
> >->reset.flags))
> continue;
> diff --git a/drivers/gpu/drm/i915/gt/intel_reset_types.h b/drivers/gpu/drm/i915/gt/intel_reset_types.h
> index 80351f0a856c..4f5fd393af6f 100644
> --- a/drivers/gpu/drm/i915/gt/intel_reset_types.h
> +++ b/drivers/gpu/drm/i915/gt/intel_reset_types.h
> @@ -41,8 +41,7 @@ struct intel_reset {
> */
> unsigned long flags;
> #define I915_RESET_BACKOFF 0
> -#define I915_RESET_MODESET 1
> -#define I915_RESET_ENGINE 2
> +#define I915_RESET_ENGINE 1
> #define I915_WEDGED_ON_INIT (BITS_PER_LONG - 3)
> #define I915_WEDGED_ON_FINI (BITS_PER_LONG - 2)
> #define I915_WEDGED (BITS_PER_LONG - 1)
> --
> 2.39.5
>
--
Matt Roper
Graphics Software Engineer
Linux GPU Platform Enablement
Intel Corporation
