From patchwork Tue Jul 9 09:31:58 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lionel Landwerlin X-Patchwork-Id: 11036717 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id D7B4314E5 for ; Tue, 9 Jul 2019 09:32:33 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id C6FBB2872F for ; Tue, 9 Jul 2019 09:32:33 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id BB07A28736; Tue, 9 Jul 2019 09:32:33 +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 7251327F2B for ; Tue, 9 Jul 2019 09:32:33 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 8A21E89DB9; Tue, 9 Jul 2019 09:32:32 +0000 (UTC) X-Original-To: intel-gfx@lists.freedesktop.org Delivered-To: intel-gfx@lists.freedesktop.org Received: from mga18.intel.com (mga18.intel.com [134.134.136.126]) by gabe.freedesktop.org (Postfix) with ESMTPS id 0701089DB9 for ; Tue, 9 Jul 2019 09:32:31 +0000 (UTC) X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by orsmga106.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 09 Jul 2019 02:32:30 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.63,470,1557212400"; d="scan'208";a="185876187" Received: from unknown (HELO delly.ger.corp.intel.com) ([10.252.37.9]) by fmsmga001.fm.intel.com with ESMTP; 09 Jul 2019 02:32:30 -0700 From: Lionel Landwerlin To: intel-gfx@lists.freedesktop.org Date: Tue, 9 Jul 2019 12:31:58 +0300 Message-Id: <20190709093208.20470-3-lionel.g.landwerlin@intel.com> X-Mailer: git-send-email 2.21.0.392.gf8f6787159e In-Reply-To: <20190709093208.20470-1-lionel.g.landwerlin@intel.com> References: <20190709093208.20470-1-lionel.g.landwerlin@intel.com> MIME-Version: 1.0 Subject: [Intel-gfx] [PATCH v7 02/12] drm/i915/perf: add missing delay for OA muxes configuration 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: , Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" X-Virus-Scanned: ClamAV using ClamSMTP Signed-off-by: Lionel Landwerlin Fixes: 19f81df2859eb1 ("drm/i915/perf: Add OA unit support for Gen 8+") Acked-by: Chris Wilson --- drivers/gpu/drm/i915/i915_perf.c | 23 +++++++++++++++++++++++ 1 file changed, 23 insertions(+) diff --git a/drivers/gpu/drm/i915/i915_perf.c b/drivers/gpu/drm/i915/i915_perf.c index 27842e7bcfed..545d3adaf341 100644 --- a/drivers/gpu/drm/i915/i915_perf.c +++ b/drivers/gpu/drm/i915/i915_perf.c @@ -1838,6 +1838,29 @@ static int gen8_enable_metric_set(struct i915_perf_stream *stream) config_oa_regs(dev_priv, oa_config->mux_regs, oa_config->mux_regs_len); + /* It apparently takes a fairly long time for a new MUX + * configuration to be be applied after these register writes. + * This delay duration was derived empirically based on the + * render_basic config but hopefully it covers the maximum + * configuration latency. + * + * As a fallback, the checks in _append_oa_reports() to skip + * invalid OA reports do also seem to work to discard reports + * generated before this config has completed - albeit not + * silently. + * + * Unfortunately this is essentially a magic number, since we + * don't currently know of a reliable mechanism for predicting + * how long the MUX config will take to apply and besides + * seeing invalid reports we don't know of a reliable way to + * explicitly check that the MUX config has landed. + * + * It's even possible we've miss characterized the underlying + * problem - it just seems like the simplest explanation why + * a delay at this location would mitigate any invalid reports. + */ + usleep_range(15000, 20000); + config_oa_regs(dev_priv, oa_config->b_counter_regs, oa_config->b_counter_regs_len);