From patchwork Thu Jun 13 10:20:19 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Sebastian Andrzej Siewior X-Patchwork-Id: 13696574 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 BF202C27C4F for ; Thu, 13 Jun 2024 10:28:37 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 0D4A610EA20; Thu, 13 Jun 2024 10:28:37 +0000 (UTC) Authentication-Results: gabe.freedesktop.org; dkim=pass (2048-bit key; secure) header.d=linutronix.de header.i=@linutronix.de header.b="PfKzSUPN"; dkim=permerror (0-bit key) header.d=linutronix.de header.i=@linutronix.de header.b="KLZe3TYX"; dkim-atps=neutral Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) by gabe.freedesktop.org (Postfix) with ESMTPS id 4378410EA0C; Thu, 13 Jun 2024 10:28:26 +0000 (UTC) From: Sebastian Andrzej Siewior DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1718274504; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=klSNWQQYRArbUq1sdGb5aifUF4FwgxDjzil4nZonFY4=; b=PfKzSUPNvC85exFqsrILD9WsMOOq0ofRF5GRAoeUrtIimqNiEAfhjNeyg8eTwCXMCpjcDP NffeX8zgFQsZIbgyrL8urUyjYBzOh3LJ2COy+Z1Vxw1vj/vTIJviaPwdYgegUgjbL08t6u Lxa1jS+u87JiCuUCc6Ji0TnC8S6D0NRA8sx95snIRAO5y84znD3RVDk+mz4UMexvqU2CD9 eKuRMjF3eIWP9auUcKV82KJljqqDJneoO9rds3LWKNMgQ4I9jg0jTqq4I9RGO+yu91p076 dvWuu0GCFzn8MNjW3YrTAzaKzYMq1MOYZd0FVwRIrIdUOA23zDonw9wgeHbh0Q== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1718274504; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=klSNWQQYRArbUq1sdGb5aifUF4FwgxDjzil4nZonFY4=; b=KLZe3TYXFB15J3rLYBwrIyesgUWJ2FA8kOQVQoJanTJ8uo7FGEYWduDhprSVLHN9SXjhlI Hfbg0jrohlS9nVDA== To: intel-gfx@lists.freedesktop.org, intel-xe@lists.freedesktop.org Cc: Jani Nikula , Joonas Lahtinen , Rodrigo Vivi , Thomas Gleixner , Tvrtko Ursulin , Mike Galbraith , Sebastian Andrzej Siewior Subject: [PATCH v2 2/8] drm/i915: Don't disable interrupts on PREEMPT_RT during atomic updates Date: Thu, 13 Jun 2024 12:20:19 +0200 Message-ID: <20240613102818.4056866-3-bigeasy@linutronix.de> In-Reply-To: <20240613102818.4056866-1-bigeasy@linutronix.de> References: <20240613102818.4056866-1-bigeasy@linutronix.de> MIME-Version: 1.0 X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" 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 --- drivers/gpu/drm/i915/display/intel_crtc.c | 9 ++++++--- drivers/gpu/drm/i915/display/intel_vblank.c | 6 ++++-- 2 files changed, 10 insertions(+), 5 deletions(-) diff --git a/drivers/gpu/drm/i915/display/intel_crtc.c b/drivers/gpu/drm/i915/display/intel_crtc.c index 25593f6aae7de..22b80004574fa 100644 --- a/drivers/gpu/drm/i915/display/intel_crtc.c +++ b/drivers/gpu/drm/i915/display/intel_crtc.c @@ -512,7 +512,8 @@ 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; @@ -530,7 +531,8 @@ 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) @@ -632,7 +634,8 @@ void intel_pipe_update_end(struct intel_atomic_state *state, */ intel_vrr_send_push(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_vblank.c b/drivers/gpu/drm/i915/display/intel_vblank.c index 71d6071121460..d639b51a49195 100644 --- a/drivers/gpu/drm/i915/display/intel_vblank.c +++ b/drivers/gpu/drm/i915/display/intel_vblank.c @@ -700,11 +700,13 @@ 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);