From patchwork Mon Jun 11 10:48:08 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chris Wilson X-Patchwork-Id: 10457525 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 C36CF601A0 for ; Mon, 11 Jun 2018 10:48:48 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id B6278283C5 for ; Mon, 11 Jun 2018 10:48:48 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id AADF0283C8; Mon, 11 Jun 2018 10:48:48 +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=-5.2 required=2.0 tests=BAYES_00, MAILING_LIST_MULTI, RCVD_IN_DNSWL_MED 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 58D80283C5 for ; Mon, 11 Jun 2018 10:48:48 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id BC2D589A60; Mon, 11 Jun 2018 10:48:47 +0000 (UTC) X-Original-To: intel-gfx@lists.freedesktop.org Delivered-To: intel-gfx@lists.freedesktop.org Received: from fireflyinternet.com (mail.fireflyinternet.com [109.228.58.192]) by gabe.freedesktop.org (Postfix) with ESMTPS id BF9D489A60 for ; Mon, 11 Jun 2018 10:48:45 +0000 (UTC) X-Default-Received-SPF: pass (skip=forwardok (res=PASS)) x-ip-name=78.156.65.138; Received: from haswell.alporthouse.com (unverified [78.156.65.138]) by fireflyinternet.com (Firefly Internet (M1)) with ESMTP id 12008956-1500050 for multiple; Mon, 11 Jun 2018 11:48:10 +0100 Received: by haswell.alporthouse.com (sSMTP sendmail emulation); Mon, 11 Jun 2018 11:48:09 +0100 From: Chris Wilson To: intel-gfx@lists.freedesktop.org Date: Mon, 11 Jun 2018 11:48:08 +0100 Message-Id: <20180611104808.24295-1-chris@chris-wilson.co.uk> X-Mailer: git-send-email 2.17.1 X-Originating-IP: 78.156.65.138 X-Country: code=GB country="United Kingdom" ip=78.156.65.138 Subject: [Intel-gfx] [PATCH] drm/i915/ringbuffer: Brute force context restore X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.23 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-Virus-Scanned: ClamAV using ClamSMTP An issue encountered with switching mm on gen7 is that the GPU likes to hang (with the VS unit busy) when told to force restore the current context. We can simply workaround this by substituting the MI_FORCE_RESTORE flag with a round-trip through the kernel_context, forcing the context to be saved and restored; thereby reloading the PP_DIR registers and updating the modified page directory! v2: Undo attempted optimisation in caller (Tvrtko) Signed-off-by: Chris Wilson Cc: Joonas Lahtinen Cc: Mika Kuoppala Cc: Matthew Auld Cc: Tvrtko Ursulin Reviewed-by: Joonas Lahtinen Reviewed-by: Mika Kuoppala --- drivers/gpu/drm/i915/intel_ringbuffer.c | 27 +++++++++++++++++++++++++ 1 file changed, 27 insertions(+) diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.c b/drivers/gpu/drm/i915/intel_ringbuffer.c index 65811e2fa7da..39108d8dcec5 100644 --- a/drivers/gpu/drm/i915/intel_ringbuffer.c +++ b/drivers/gpu/drm/i915/intel_ringbuffer.c @@ -1458,6 +1458,7 @@ static inline int mi_set_context(struct i915_request *rq, u32 flags) (HAS_LEGACY_SEMAPHORES(i915) && IS_GEN7(i915)) ? INTEL_INFO(i915)->num_rings - 1 : 0; + bool force_restore = false; int len; u32 *cs; @@ -1471,6 +1472,12 @@ static inline int mi_set_context(struct i915_request *rq, u32 flags) len = 4; if (IS_GEN7(i915)) len += 2 + (num_rings ? 4*num_rings + 6 : 0); + if (flags & MI_FORCE_RESTORE) { + GEM_BUG_ON(flags & MI_RESTORE_INHIBIT); + flags &= ~MI_FORCE_RESTORE; + force_restore = true; + len += 2; + } cs = intel_ring_begin(rq, len); if (IS_ERR(cs)) @@ -1495,6 +1502,26 @@ static inline int mi_set_context(struct i915_request *rq, u32 flags) } } + if (force_restore) { + /* + * The HW doesn't handle being told to restore the current + * context very well. Quite often it likes goes to go off and + * sulk, especially when it is meant to be reloading PP_DIR. + * A very simple fix to force the reload is to simply switch + * away from the current context and back again. + * + * Note that the kernel_context will contain random state + * following the INHIBIT_RESTORE. We accept this since we + * never use the kernel_context state; it is merely a + * placeholder we use to flush other contexts. + */ + *cs++ = MI_SET_CONTEXT; + *cs++ = i915_ggtt_offset(to_intel_context(i915->kernel_context, + engine)->state) | + MI_MM_SPACE_GTT | + MI_RESTORE_INHIBIT; + } + *cs++ = MI_NOOP; *cs++ = MI_SET_CONTEXT; *cs++ = i915_ggtt_offset(rq->hw_context->state) | flags;