From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 15A9BCCD1AB for ; Wed, 22 Oct 2025 12:13:15 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id CC68E10E769; Wed, 22 Oct 2025 12:13:14 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; unprotected) header.d=lankhorst.se header.i=@lankhorst.se header.b="RCCDIUmG"; dkim-atps=neutral Received: from lankhorst.se (lankhorst.se [141.105.120.124]) by gabe.freedesktop.org (Postfix) with ESMTPS id 24B3C10E76A for ; Wed, 22 Oct 2025 12:13:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=lankhorst.se; s=default; t=1761135191; bh=oGg2WvZ0Zmdh/NwOHM0WiFbf+HRBxnlQJSGs+UvcTe0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=RCCDIUmGSdDswUZlbhU9n8UMQMMYHTuthzgf5SkNww/a5CFXNheUyJ/PR5Dqgys+1 ykgwFyirUToxRFJUBzdegI0l0jkUAyHO1ECIlNBObqJsWBwu+S8+WOkpS6wiigD4tu uC2z4XxgaO4TEOWKh6Na4IppHdiyD98wkIwiuif2EVx4rMbklhtUARQK70RmLe131X Clh3D3Btq/FgCZfMrVx5MudiikgR66k/bFUunbM5ZnuQgfgay3/Mde6Q65SuvTPhzY iGnlqDDHIrSaL22Xu0lwZ2DKTx0i89ZRt+iTdC4uyMB5p8px9vW7U+nn6dhGGW0Bvl uptS94YBR6q3A== From: Maarten Lankhorst To: intel-xe@lists.freedesktop.org Cc: Mike Galbraith , Sebastian Andrzej Siewior , Maarten Lankhorst Subject: [FOR CI 3/5] drm/i915: Don't disable interrupts on PREEMPT_RT during atomic updates Date: Wed, 22 Oct 2025 14:13:05 +0200 Message-ID: <20251022121301.18166-10-dev@lankhorst.se> X-Mailer: git-send-email 2.51.0 In-Reply-To: <20251022121301.18166-7-dev@lankhorst.se> References: <20251022121301.18166-7-dev@lankhorst.se> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-BeenThere: intel-xe@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel Xe graphics driver List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-xe-bounces@lists.freedesktop.org Sender: "Intel-xe" From: Mike Galbraith Commit 8d7849db3eab7 ("drm/i915: Make sprite updates atomic") started disabling interrupts across atomic updates. This breaks on PREEMPT_RT because within this section the code attempt to acquire spinlock_t locks which are sleeping locks on PREEMPT_RT. According to the comment the interrupts are disabled to avoid random delays and not required for protection or synchronisation. If this needs to happen with disabled interrupts on PREEMPT_RT, and the whole section is restricted to register access then all sleeping locks need to be acquired before interrupts are disabled and some function maybe moved after enabling interrupts again. This includes: - prepare_to_wait() + finish_wait() due its wake queue. - drm_crtc_vblank_put() -> vblank_disable_fn() drm_device::vbl_lock. - skl_pfit_enable(), intel_update_plane(), vlv_atomic_update_fifo() and maybe others due to intel_uncore::lock - drm_crtc_arm_vblank_event() due to drm_device::event_lock and drm_device::vblank_time_lock. Don't disable interrupts on PREEMPT_RT during atomic updates. [bigeasy: drop local locks, commit message] Signed-off-by: Mike Galbraith Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Maarten Lankhorst --- drivers/gpu/drm/i915/display/intel_crtc.c | 9 ++++++--- drivers/gpu/drm/i915/display/intel_cursor.c | 9 ++++++--- drivers/gpu/drm/i915/display/intel_vblank.c | 6 ++++-- 3 files changed, 16 insertions(+), 8 deletions(-) diff --git a/drivers/gpu/drm/i915/display/intel_crtc.c b/drivers/gpu/drm/i915/display/intel_crtc.c index d300ba1dcd2c4..f34745b5ea497 100644 --- a/drivers/gpu/drm/i915/display/intel_crtc.c +++ b/drivers/gpu/drm/i915/display/intel_crtc.c @@ -567,7 +567,8 @@ void intel_pipe_update_start(struct intel_atomic_state *state, */ intel_psr_wait_for_idle_locked(new_crtc_state); - local_irq_disable(); + if (!IS_ENABLED(CONFIG_PREEMPT_RT)) + local_irq_disable(); crtc->debug.min_vbl = evade.min; crtc->debug.max_vbl = evade.max; @@ -585,7 +586,8 @@ void intel_pipe_update_start(struct intel_atomic_state *state, return; irq_disable: - local_irq_disable(); + if (!IS_ENABLED(CONFIG_PREEMPT_RT)) + local_irq_disable(); } #if IS_ENABLED(CONFIG_DRM_I915_DEBUG_VBLANK_EVADE) @@ -731,7 +733,8 @@ void intel_pipe_update_end(struct intel_atomic_state *state, if (!state->base.legacy_cursor_update) intel_vrr_send_push(NULL, new_crtc_state); - local_irq_enable(); + if (!IS_ENABLED(CONFIG_PREEMPT_RT)) + local_irq_enable(); if (intel_vgpu_active(dev_priv)) goto out; diff --git a/drivers/gpu/drm/i915/display/intel_cursor.c b/drivers/gpu/drm/i915/display/intel_cursor.c index c47c849358714..780fcae77a984 100644 --- a/drivers/gpu/drm/i915/display/intel_cursor.c +++ b/drivers/gpu/drm/i915/display/intel_cursor.c @@ -919,13 +919,15 @@ intel_legacy_cursor_update(struct drm_plane *_plane, */ intel_psr_wait_for_idle_locked(crtc_state); - local_irq_disable(); + if (!IS_ENABLED(CONFIG_PREEMPT_RT)) + local_irq_disable(); intel_vblank_evade(&evade); drm_crtc_vblank_put(&crtc->base); } else { - local_irq_disable(); + if (!IS_ENABLED(CONFIG_PREEMPT_RT)) + local_irq_disable(); } if (new_plane_state->uapi.visible) { @@ -935,7 +937,8 @@ intel_legacy_cursor_update(struct drm_plane *_plane, intel_plane_disable_arm(NULL, plane, crtc_state); } - local_irq_enable(); + if (!IS_ENABLED(CONFIG_PREEMPT_RT)) + local_irq_enable(); intel_psr_unlock(crtc_state); diff --git a/drivers/gpu/drm/i915/display/intel_vblank.c b/drivers/gpu/drm/i915/display/intel_vblank.c index 5206a81f85554..7826f29619a14 100644 --- a/drivers/gpu/drm/i915/display/intel_vblank.c +++ b/drivers/gpu/drm/i915/display/intel_vblank.c @@ -761,11 +761,13 @@ int intel_vblank_evade(struct intel_vblank_evade_ctx *evade) break; } - local_irq_enable(); + if (!IS_ENABLED(CONFIG_PREEMPT_RT)) + local_irq_enable(); timeout = schedule_timeout(timeout); - local_irq_disable(); + if (!IS_ENABLED(CONFIG_PREEMPT_RT)) + local_irq_disable(); } finish_wait(wq, &wait); -- 2.51.0