From patchwork Thu Jul 27 16:42:44 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Jordan Crouse X-Patchwork-Id: 9867365 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id C087F603F9 for ; Thu, 27 Jul 2017 16:44:40 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id B2E652882E for ; Thu, 27 Jul 2017 16:44:40 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id A596D28844; Thu, 27 Jul 2017 16:44:40 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.1 required=2.0 tests=BAYES_00,DKIM_SIGNED, RCVD_IN_DNSWL_MED,T_DKIM_INVALID autolearn=ham version=3.3.1 Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) (using TLSv1.2 with cipher DHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.wl.linuxfoundation.org (Postfix) with ESMTPS id 7672528835 for ; Thu, 27 Jul 2017 16:44:39 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id AD2896EE5E; Thu, 27 Jul 2017 16:43:25 +0000 (UTC) X-Original-To: dri-devel@lists.freedesktop.org Delivered-To: dri-devel@lists.freedesktop.org Received: from smtp.codeaurora.org (smtp.codeaurora.org [198.145.29.96]) by gabe.freedesktop.org (Postfix) with ESMTPS id 45F796EE33; Thu, 27 Jul 2017 16:43:04 +0000 (UTC) Received: by smtp.codeaurora.org (Postfix, from userid 1000) id CA26860B72; Thu, 27 Jul 2017 16:43:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1501173784; bh=Cc65IqkygN24X3kmDF9X2dPyeszs9/CO4reaq6dSLVA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=fzmKbUw6M85v6fsE7vhcSspxrlFEfzDPK//Zo5LJTgvtLWIVlOwAZBoLbG1g7LnoN aPRUzwGGPPIZaX0I0ZyKUf8kPXiDNHSAFJskKkdtKsX+yUHX1XUK3wyUu/nM/h3Q6L 6QcrpZLrNtKCw5UDTX+6BnxKxJ737uFrHFI14yRI= Received: from jcrouse-lnx.qualcomm.com (i-global254.qualcomm.com [199.106.103.254]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-SHA256 (128/128 bits)) (No client certificate requested) (Authenticated sender: jcrouse@smtp.codeaurora.org) by smtp.codeaurora.org (Postfix) with ESMTPSA id 4464660CF5; Thu, 27 Jul 2017 16:43:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=codeaurora.org; s=default; t=1501173781; bh=Cc65IqkygN24X3kmDF9X2dPyeszs9/CO4reaq6dSLVA=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Lv/ro2YMYBf/gtbZLUe3d1zXwAgU/DaIBZtQCe59GhDrWyFMLocxC3qEuzlEOkB54 KbbdU77mAbSWsd58CTK0pbIsw8OEkXX3mPb0eireYz35fmxsSFozKrVNlqdXjWKzlu qISPDmyE6cMElsKGEpx+1VKVWxQksK5N5UAdhUkg= DMARC-Filter: OpenDMARC Filter v1.3.2 smtp.codeaurora.org 4464660CF5 Authentication-Results: pdx-caf-mail.web.codeaurora.org; dmarc=none (p=none dis=none) header.from=codeaurora.org Authentication-Results: pdx-caf-mail.web.codeaurora.org; spf=none smtp.mailfrom=jcrouse@codeaurora.org From: Jordan Crouse To: freedreno@lists.freedesktop.org Subject: [PATCH 15/17] drm/msm: Shadow current pointer in the ring until command is complete Date: Thu, 27 Jul 2017 10:42:44 -0600 Message-Id: <1501173766-24856-16-git-send-email-jcrouse@codeaurora.org> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1501173766-24856-1-git-send-email-jcrouse@codeaurora.org> References: <1501173766-24856-1-git-send-email-jcrouse@codeaurora.org> Cc: linux-arm-msm@vger.kernel.org, dri-devel@lists.freedesktop.org X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.18 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , MIME-Version: 1.0 Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" X-Virus-Scanned: ClamAV using ClamSMTP Add a shadow pointer to track the current command being written into the ring. Don't commit it as 'cur' until the command is submitted. Because 'cur' is used to construct the software copy of the wptr this ensures that somebody peeking in on the ring doesn't assume that a command is inflight while it is being written. This isn't a huge deal with a single ring (though technically the hangcheck could assume the system is prematurely busy when it isn't) but it will be rather important for preemption where the decision to preempt is based on a non-empty ringbuffer. Without a shadow an aggressive preemption scheme could assume that the ringbuffer is non empty and switch to it before the CPU is done writing the command and boom. Even though preemption won't be supported for all targets because of the way the code is organized it is simpler to make this generic for all targets. The extra load for non-preemption targets should be minimal. Signed-off-by: Jordan Crouse --- drivers/gpu/drm/msm/adreno/adreno_gpu.c | 9 +++++++-- drivers/gpu/drm/msm/msm_ringbuffer.c | 1 + drivers/gpu/drm/msm/msm_ringbuffer.h | 12 ++++++++---- 3 files changed, 16 insertions(+), 6 deletions(-) diff --git a/drivers/gpu/drm/msm/adreno/adreno_gpu.c b/drivers/gpu/drm/msm/adreno/adreno_gpu.c index 39ff842..a2777d8 100644 --- a/drivers/gpu/drm/msm/adreno/adreno_gpu.c +++ b/drivers/gpu/drm/msm/adreno/adreno_gpu.c @@ -82,6 +82,7 @@ int adreno_hw_init(struct msm_gpu *gpu) } ring->cur = ring->start; + ring->next = ring->start; /* reset completed fence seqno: */ ring->memptrs->fence = ring->seqno; @@ -226,12 +227,15 @@ void adreno_flush(struct msm_gpu *gpu, struct msm_ringbuffer *ring) struct adreno_gpu *adreno_gpu = to_adreno_gpu(gpu); uint32_t wptr; + /* Copy the shadow to the actual register */ + ring->cur = ring->next; + /* * Mask wptr value that we calculate to fit in the HW range. This is * to account for the possibility that the last command fit exactly into * the ringbuffer and rb->next hasn't wrapped to zero yet */ - wptr = get_wptr(ring) % (MSM_GPU_RINGBUFFER_SZ >> 2); + wptr = (ring->cur - ring->start) % (MSM_GPU_RINGBUFFER_SZ >> 2); /* ensure writes to ringbuffer have hit system memory: */ mb(); @@ -343,7 +347,8 @@ static uint32_t ring_freewords(struct msm_ringbuffer *ring) { struct adreno_gpu *adreno_gpu = to_adreno_gpu(ring->gpu); uint32_t size = MSM_GPU_RINGBUFFER_SZ >> 2; - uint32_t wptr = get_wptr(ring); + /* Use ring->next to calculate free size */ + uint32_t wptr = ring->next - ring->start; uint32_t rptr = get_rptr(adreno_gpu, ring); return (rptr + (size - 1) - wptr) % size; } diff --git a/drivers/gpu/drm/msm/msm_ringbuffer.c b/drivers/gpu/drm/msm/msm_ringbuffer.c index a74d66a..899145b 100644 --- a/drivers/gpu/drm/msm/msm_ringbuffer.c +++ b/drivers/gpu/drm/msm/msm_ringbuffer.c @@ -45,6 +45,7 @@ struct msm_ringbuffer *msm_ringbuffer_new(struct msm_gpu *gpu, int id, goto fail; } ring->end = ring->start + (MSM_GPU_RINGBUFFER_SZ >> 2); + ring->next = ring->start; ring->cur = ring->start; ring->memptrs = memptrs; diff --git a/drivers/gpu/drm/msm/msm_ringbuffer.h b/drivers/gpu/drm/msm/msm_ringbuffer.h index 5907063f..8cff38a 100644 --- a/drivers/gpu/drm/msm/msm_ringbuffer.h +++ b/drivers/gpu/drm/msm/msm_ringbuffer.h @@ -32,7 +32,7 @@ struct msm_ringbuffer { struct msm_gpu *gpu; int id; struct drm_gem_object *bo; - uint32_t *start, *end, *cur; + uint32_t *start, *end, *cur, *next; struct list_head submits; uint64_t iova; uint32_t seqno; @@ -50,9 +50,13 @@ struct msm_ringbuffer *msm_ringbuffer_new(struct msm_gpu *gpu, int id, static inline void OUT_RING(struct msm_ringbuffer *ring, uint32_t data) { - if (ring->cur == ring->end) - ring->cur = ring->start; - *(ring->cur++) = data; + /* + * ring->next points to the current command being written - it won't be + * committed as ring->cur until the flush + */ + if (ring->next == ring->end) + ring->next = ring->start; + *(ring->next++) = data; } #endif /* __MSM_RINGBUFFER_H__ */