From patchwork Fri Aug 16 00:31:04 2013 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: James Ausmus X-Patchwork-Id: 2845320 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 [198.145.19.201]) by patchwork2.web.kernel.org (Postfix) with ESMTP id 87B6ABF546 for ; Fri, 16 Aug 2013 00:41:17 +0000 (UTC) Received: from mail.kernel.org (localhost [127.0.0.1]) by mail.kernel.org (Postfix) with ESMTP id 9DC36202A7 for ; Fri, 16 Aug 2013 00:41:16 +0000 (UTC) Received: from gabe.freedesktop.org (gabe.freedesktop.org [131.252.210.177]) by mail.kernel.org (Postfix) with ESMTP id 9B2DB2021E for ; Fri, 16 Aug 2013 00:41:15 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 8C948E7838 for ; Thu, 15 Aug 2013 17:41:15 -0700 (PDT) X-Original-To: intel-gfx@lists.freedesktop.org Delivered-To: intel-gfx@lists.freedesktop.org Received: from mga02.intel.com (mga02.intel.com [134.134.136.20]) by gabe.freedesktop.org (Postfix) with ESMTP id BB273E665C for ; Thu, 15 Aug 2013 17:31:59 -0700 (PDT) Received: from orsmga002.jf.intel.com ([10.7.209.21]) by orsmga101.jf.intel.com with ESMTP; 15 Aug 2013 17:31:57 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.89,889,1367996400"; d="scan'208";a="387901471" Received: from jausmus-gentoo-dev5.jf.intel.com ([10.7.198.60]) by orsmga002.jf.intel.com with ESMTP; 15 Aug 2013 17:31:57 -0700 From: james.ausmus@intel.com To: intel-gfx@lists.freedesktop.org Date: Thu, 15 Aug 2013 17:31:04 -0700 Message-Id: <1376613069-15790-40-git-send-email-james.ausmus@intel.com> X-Mailer: git-send-email 1.8.3.2 In-Reply-To: <1376613069-15790-1-git-send-email-james.ausmus@intel.com> References: <1376613069-15790-1-git-send-email-james.ausmus@intel.com> MIME-Version: 1.0 Subject: [Intel-gfx] [PATCH] CHROMIUM: drm/i915: Work around PPT chipsets wakeup delays X-BeenThere: intel-gfx@lists.freedesktop.org X-Mailman-Version: 2.1.13 Precedence: list List-Id: Intel graphics driver community testing & development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: intel-gfx-bounces+patchwork-intel-gfx=patchwork.kernel.org@lists.freedesktop.org Errors-To: intel-gfx-bounces+patchwork-intel-gfx=patchwork.kernel.org@lists.freedesktop.org X-Spam-Status: No, score=-7.0 required=5.0 tests=BAYES_00, RCVD_IN_DNSWL_MED, 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 From: Stéphane Marchesin Right after resume, panther point chipsets seem to ignore all register writes. But if you wait a bit and retry, everything works fine. I empirically measured that the window where it is flakey lasts around 25ms, so let's sleep 30ms after turning on the PCH clock. BUG=chrome-os-partner:20542 TEST=by hand: resume parrot a couple times, everything works as expected Change-Id: I3281ff8ef5f43f6f73088a47500a557839acbdc0 Reviewed-on: https://gerrit.chromium.org/gerrit/60164 Reviewed-by: Stuart Abercrombie Commit-Queue: Stéphane Marchesin Tested-by: Stéphane Marchesin --- drivers/gpu/drm/i915/intel_display.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/drivers/gpu/drm/i915/intel_display.c b/drivers/gpu/drm/i915/intel_display.c index 7d13b34..c933bfa 100644 --- a/drivers/gpu/drm/i915/intel_display.c +++ b/drivers/gpu/drm/i915/intel_display.c @@ -4833,6 +4833,15 @@ static void ironlake_init_pch_refclk(struct drm_device *dev) POSTING_READ(PCH_DREF_CONTROL); udelay(200); } + + /* + * On resume, the PPT PCH doesn't seem to work right away, and + * sometimes ignores register read/writes until it's completely up. + * Waiting 30ms seems to be long enough to avoid this. + */ + if (dev_priv->pch_id == INTEL_PCH_PPT_DEVICE_ID_TYPE) + msleep(30); + } /* Sequence to enable CLKOUT_DP for FDI usage and configure PCH FDI I/O. */