From patchwork Thu Jan 20 17:41:19 2011 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chris Wilson X-Patchwork-Id: 492311 Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) by demeter1.kernel.org (8.14.4/8.14.3) with ESMTP id p0KHg4wS019686 for ; Thu, 20 Jan 2011 17:42:31 GMT Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id EC7C69EBEF for ; Thu, 20 Jan 2011 09:42:03 -0800 (PST) X-Original-To: dri-devel@lists.freedesktop.org Delivered-To: dri-devel@lists.freedesktop.org Received: from fireflyinternet.com (server109-228-6-236.live-servers.net [109.228.6.236]) by gabe.freedesktop.org (Postfix) with ESMTP id ED4809E792 for ; Thu, 20 Jan 2011 09:41:30 -0800 (PST) X-Default-Received-SPF: pass (skip=forwardok (res=PASS)) x-ip-name=78.156.66.37; Received: from arrandale.alporthouse.com (unverified [78.156.66.37]) by fireflyinternet.com (Firefly Internet SMTP) with ESMTP id 23322186-1500050 for multiple; Thu, 20 Jan 2011 17:41:23 +0000 From: Chris Wilson To: Subject: [PATCH] drm/i915/ringbuffer: Fix use of stale HEAD position whilst polling for space Date: Thu, 20 Jan 2011 17:41:19 +0000 Message-Id: <1295545279-21335-1-git-send-email-chris@chris-wilson.co.uk> X-Mailer: git-send-email 1.7.2.3 In-Reply-To: References: X-To-Not-Matched: true X-Originating-IP: 78.156.66.37 Cc: dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.11 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Sender: dri-devel-bounces+patchwork-dri-devel=patchwork.kernel.org@lists.freedesktop.org Errors-To: dri-devel-bounces+patchwork-dri-devel=patchwork.kernel.org@lists.freedesktop.org X-Greylist: IP, sender and recipient auto-whitelisted, not delayed by milter-greylist-4.2.6 (demeter1.kernel.org [140.211.167.41]); Thu, 20 Jan 2011 17:42:43 +0000 (UTC) diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c index 51fbc5e..6218fa9 100644 --- a/drivers/gpu/drm/i915/intel_ringbuffer.c +++ b/drivers/gpu/drm/i915/intel_ringbuffer.c @@ -34,6 +34,14 @@ #include "i915_trace.h" #include "intel_drv.h" +static inline int ring_space(struct intel_ring_buffer *ring) +{ + int space = (ring->head & HEAD_ADDR) - (ring->tail + 8); + if (space < 0) + space += ring->size; + return space; +} + static u32 i915_gem_get_seqno(struct drm_device *dev) { drm_i915_private_t *dev_priv = dev->dev_private; @@ -204,11 +212,9 @@ static int init_ring_common(struct intel_ring_buffer *ring) if (!drm_core_check_feature(ring->dev, DRIVER_MODESET)) i915_kernel_lost_context(ring->dev); else { - ring->head = I915_READ_HEAD(ring) & HEAD_ADDR; + ring->head = I915_READ_HEAD(ring); ring->tail = I915_READ_TAIL(ring) & TAIL_ADDR; - ring->space = ring->head - (ring->tail + 8); - if (ring->space < 0) - ring->space += ring->size; + ring->space = ring_space(ring); } return 0; @@ -921,7 +927,7 @@ static int intel_wrap_ring_buffer(struct intel_ring_buffer *ring) } ring->tail = 0; - ring->space = ring->head - 8; + ring->space = ring_space(ring); return 0; } @@ -933,20 +939,22 @@ int intel_wait_ring_buffer(struct intel_ring_buffer *ring, int n) unsigned long end; u32 head; + /* If the reported head position has wrapped or hasn't advanced, + * fallback to the slow and accurate path. + */ + head = intel_read_status_page(ring, 4); + if (head > ring->head) { + ring->head = head; + ring->space = ring_space(ring); + if (ring->space >= n) + return 0; + } + trace_i915_ring_wait_begin (dev); end = jiffies + 3 * HZ; do { - /* If the reported head position has wrapped or hasn't advanced, - * fallback to the slow and accurate path. - */ - head = intel_read_status_page(ring, 4); - if (head < ring->actual_head) - head = I915_READ_HEAD(ring); - ring->actual_head = head; - ring->head = head & HEAD_ADDR; - ring->space = ring->head - (ring->tail + 8); - if (ring->space < 0) - ring->space += ring->size; + ring->head = I915_READ_HEAD(ring); + ring->space = ring_space(ring); if (ring->space >= n) { trace_i915_ring_wait_end(dev); return 0; diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h index 61d5220..6d6fde8 100644 --- a/drivers/gpu/drm/i915/intel_ringbuffer.h +++ b/drivers/gpu/drm/i915/intel_ringbuffer.h @@ -47,7 +47,6 @@ struct intel_ring_buffer { struct drm_device *dev; struct drm_i915_gem_object *obj; - u32 actual_head; u32 head; u32 tail; int space;