From patchwork Mon Sep 28 12:25:12 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Michel Thierry X-Patchwork-Id: 7276831 Return-Path: X-Original-To: patchwork-intel-gfx@patchwork.kernel.org Delivered-To: patchwork-parsemail@patchwork2.web.kernel.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.136]) by patchwork2.web.kernel.org (Postfix) with ESMTP id E5F82BEEA4 for ; Mon, 28 Sep 2015 12:25:23 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id E6DF920765 for ; Mon, 28 Sep 2015 12:25:22 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) by mail.kernel.org (Postfix) with ESMTP id 3E70C20763 for ; Mon, 28 Sep 2015 12:25:17 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id B510D6E9BC; Mon, 28 Sep 2015 05:25:16 -0700 (PDT) X-Original-To: intel-gfx@lists.freedesktop.org Delivered-To: intel-gfx@lists.freedesktop.org Received: from mga09.intel.com (mga09.intel.com [134.134.136.24]) by gabe.freedesktop.org (Postfix) with ESMTP id 4D5386E9BC for ; Mon, 28 Sep 2015 05:25:15 -0700 (PDT) Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by orsmga102.jf.intel.com with ESMTP; 28 Sep 2015 05:25:16 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.17,602,1437462000"; d="scan'208";a="569780212" Received: from michelth-linux2.isw.intel.com ([10.102.226.189]) by FMSMGA003.fm.intel.com with ESMTP; 28 Sep 2015 05:25:13 -0700 From: Michel Thierry To: intel-gfx@lists.freedesktop.org Date: Mon, 28 Sep 2015 13:25:12 +0100 Message-Id: <1443443112-31375-1-git-send-email-michel.thierry@intel.com> X-Mailer: git-send-email 2.5.3 In-Reply-To: <1443019430-20792-1-git-send-email-michel.thierry@intel.com> References: <1443019430-20792-1-git-send-email-michel.thierry@intel.com> Subject: [Intel-gfx] [PATCH v2] drm/i915: Consider HW CSB write pointer before resetting the sw read pointer X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.18 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" X-Spam-Status: No, score=-4.2 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, T_RP_MATCHES_RCVD, UNPARSEABLE_RELAY autolearn=unavailable version=3.3.1 X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on mail.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP A previous commit resets the Context Status Buffer (CSB) read pointer in ring init commit c0a03a2e4c4e ("drm/i915: Reset CSB read pointer in ring init") This is generally correct, but this pointer is not reset after suspend/resume in some platforms (cht). In this case, the driver should read the register value instead of resetting the sw read counter to 0. Otherwise we process old events, leading to unwanted pre-emptions or something worse. But in other platforms (bdw) and also during GPU reset or power up, the CSBWP is reset to 0x7 (an invalid number), and in this case the read pointer should be set to 5 (the interrupt code will increment this counter one more time, and will start reading from CSB[0]). v2: When the CSB registers are reset, the read pointer needs to be set to 5, otherwise the first write (CSB[0]) won't be read (Mika). Replace magic numbers with GEN8_CSB_ENTRIES (6) and GEN8_CSB_PTR_MASK (0x07). Cc: Mika Kuoppala Signed-off-by: Lei Shen Signed-off-by: Deepak S Signed-off-by: Michel Thierry --- drivers/gpu/drm/i915/intel_lrc.c | 39 ++++++++++++++++++++++++++++++++------- drivers/gpu/drm/i915/intel_lrc.h | 2 ++ 2 files changed, 34 insertions(+), 7 deletions(-) diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c index ff9a481..ee25731 100644 --- a/drivers/gpu/drm/i915/intel_lrc.c +++ b/drivers/gpu/drm/i915/intel_lrc.c @@ -511,18 +511,18 @@ void intel_lrc_irq_handler(struct intel_engine_cs *ring) status_pointer = I915_READ(RING_CONTEXT_STATUS_PTR(ring)); read_pointer = ring->next_context_status_buffer; - write_pointer = status_pointer & 0x07; + write_pointer = status_pointer & GEN8_CSB_PTR_MASK; if (read_pointer > write_pointer) - write_pointer += 6; + write_pointer += GEN8_CSB_ENTRIES; spin_lock(&ring->execlist_lock); while (read_pointer < write_pointer) { read_pointer++; status = I915_READ(RING_CONTEXT_STATUS_BUF(ring) + - (read_pointer % 6) * 8); + (read_pointer % GEN8_CSB_ENTRIES) * 8); status_id = I915_READ(RING_CONTEXT_STATUS_BUF(ring) + - (read_pointer % 6) * 8 + 4); + (read_pointer % GEN8_CSB_ENTRIES) * 8 + 4); if (status & GEN8_CTX_STATUS_IDLE_ACTIVE) continue; @@ -554,10 +554,12 @@ void intel_lrc_irq_handler(struct intel_engine_cs *ring) spin_unlock(&ring->execlist_lock); WARN(submit_contexts > 2, "More than two context complete events?\n"); - ring->next_context_status_buffer = write_pointer % 6; + ring->next_context_status_buffer = write_pointer % GEN8_CSB_ENTRIES; I915_WRITE(RING_CONTEXT_STATUS_PTR(ring), - _MASKED_FIELD(0x07 << 8, ((u32)ring->next_context_status_buffer & 0x07) << 8)); + _MASKED_FIELD(GEN8_CSB_PTR_MASK << 8, + ((u32)ring->next_context_status_buffer & + GEN8_CSB_PTR_MASK) << 8)); } static int execlists_context_queue(struct drm_i915_gem_request *request) @@ -1479,6 +1481,7 @@ static int gen8_init_common_ring(struct intel_engine_cs *ring) { struct drm_device *dev = ring->dev; struct drm_i915_private *dev_priv = dev->dev_private; + u8 next_context_status_buffer_hw; lrc_setup_hardware_status_page(ring, ring->default_context->engine[ring->id].state); @@ -1496,7 +1499,29 @@ static int gen8_init_common_ring(struct intel_engine_cs *ring) _MASKED_BIT_DISABLE(GFX_REPLAY_MODE) | _MASKED_BIT_ENABLE(GFX_RUN_LIST_ENABLE)); POSTING_READ(RING_MODE_GEN7(ring)); - ring->next_context_status_buffer = 0; + + /* + * Instead of resetting the Context Status Buffer (CSB) read pointer to + * zero, we need to read the write pointer from hardware and use its + * value because "this register is power context save restored". + * Effectively, these states have been observed: + * + * | Suspend-to-idle (freeze) | Suspend-to-RAM (mem) | + * BDW | CSB regs not reset | CSB regs reset | + * CHT | CSB regs not reset | CSB regs not reset | + */ + next_context_status_buffer_hw = (I915_READ(RING_CONTEXT_STATUS_PTR(ring)) + & GEN8_CSB_PTR_MASK); + + /* + * When the CSB registers are reset (also after power-up / gpu reset), + * CSB write pointer is set to all 1's, which is not valid, use '5' in + * this special case, so the first element read is CSB[0]. + */ + if (next_context_status_buffer_hw == GEN8_CSB_PTR_MASK) + next_context_status_buffer_hw = (GEN8_CSB_ENTRIES - 1); + + ring->next_context_status_buffer = next_context_status_buffer_hw; DRM_DEBUG_DRIVER("Execlists enabled for %s\n", ring->name); memset(&ring->hangcheck, 0, sizeof(ring->hangcheck)); diff --git a/drivers/gpu/drm/i915/intel_lrc.h b/drivers/gpu/drm/i915/intel_lrc.h index 69d99f0..20fefb7 100644 --- a/drivers/gpu/drm/i915/intel_lrc.h +++ b/drivers/gpu/drm/i915/intel_lrc.h @@ -25,6 +25,8 @@ #define _INTEL_LRC_H_ #define GEN8_LR_CONTEXT_ALIGN 4096 +#define GEN8_CSB_ENTRIES 6 +#define GEN8_CSB_PTR_MASK 0x07 /* Execlists regs */ #define RING_ELSP(ring) ((ring)->mmio_base+0x230)