From patchwork Fri Jun 30 19:08:13 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: jim.bride@linux.intel.com X-Patchwork-Id: 9820269 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 3E10860224 for ; Fri, 30 Jun 2017 19:10:53 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 2F49828449 for ; Fri, 30 Jun 2017 19:10:53 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 240E4284AF; Fri, 30 Jun 2017 19:10:53 +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=-4.2 required=2.0 tests=BAYES_00, 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 CC33428449 for ; Fri, 30 Jun 2017 19:10:52 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 61BC86E864; Fri, 30 Jun 2017 19:10:52 +0000 (UTC) X-Original-To: intel-gfx@lists.freedesktop.org Delivered-To: intel-gfx@lists.freedesktop.org Received: from mga06.intel.com (mga06.intel.com [134.134.136.31]) by gabe.freedesktop.org (Postfix) with ESMTPS id 7DE346E85C for ; Fri, 30 Jun 2017 19:10:43 +0000 (UTC) Received: from fmsmga006.fm.intel.com ([10.253.24.20]) by orsmga104.jf.intel.com with ESMTP; 30 Jun 2017 12:10:43 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.40,288,1496127600"; d="scan'208";a="121445566" Received: from shiv.jf.intel.com ([10.54.75.141]) by fmsmga006.fm.intel.com with ESMTP; 30 Jun 2017 12:10:43 -0700 From: Jim Bride To: intel-gfx@lists.freedesktop.org Date: Fri, 30 Jun 2017 12:08:13 -0700 Message-Id: <1498849693-26240-5-git-send-email-jim.bride@linux.intel.com> X-Mailer: git-send-email 2.7.4 In-Reply-To: <1498849693-26240-1-git-send-email-jim.bride@linux.intel.com> References: <1498849693-26240-1-git-send-email-jim.bride@linux.intel.com> Cc: Jani Nikula , Paulo Zanoni , Rodrigo Vivi Subject: [Intel-gfx] [PATCH v2 4/4] drm/i915/psr: Account for sink CRC raciness on some panels 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-Virus-Scanned: ClamAV using ClamSMTP According to the eDP spec, when the count field in TEST_SINK_MISC increments then the six bytes of sink CRC information in the DPCD should be valid. Unfortunately, this doesn't seem to be the case on some panels, and as a result we get some incorrect and inconsistent values from the sink CRC DPCD locations at times. This problem exhibits itself more on faster processors (relative failure rates HSW < SKL < KBL.) In order to try and account for this, we try a lot harder to read the sink CRC until we get consistent values twice in a row before returning what we read and delay for a time before trying to read. We still see some occasional failures, but reading the sink CRC is much more reliable, particularly on SKL and KBL, with these changes than without. v2: * Reduce number of retries when reading the sink CRC (Jani) * Refactor to minimize changes to the code (Jani) * Rebase Cc: Rodrigo Vivi Cc: Paulo Zanoni Cc: Jani Nikula Signed-off-by: Jim Bride Reviewed-by: Rodrigo Vivi --- drivers/gpu/drm/i915/intel_dp.c | 40 ++++++++++++++++++++++++++++++++++++---- 1 file changed, 36 insertions(+), 4 deletions(-) diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c index b46fa03..1fe0975 100644 --- a/drivers/gpu/drm/i915/intel_dp.c +++ b/drivers/gpu/drm/i915/intel_dp.c @@ -3927,6 +3927,14 @@ int intel_dp_sink_crc(struct intel_dp *intel_dp, u8 *crc) u8 buf; int count, ret; int attempts = 6; + u8 old_crc[6]; + + if (crc != NULL) { + memset(crc, 0, 6); + memset(old_crc, 0xff, 6); + } else { + return -ENOMEM; + } ret = intel_dp_sink_crc_start(intel_dp); if (ret) @@ -3950,11 +3958,35 @@ int intel_dp_sink_crc(struct intel_dp *intel_dp, u8 *crc) goto stop; } - if (drm_dp_dpcd_read(&intel_dp->aux, DP_TEST_CRC_R_CR, crc, 6) < 0) { - ret = -EIO; - goto stop; - } + attempts = 6; + + /* + * Sometimes it takes a while for the "real" CRC values to land in + * the DPCD, so try several times until we get two reads in a row + * that are the same. If we're an eDP panel, delay between reads + * for a while since the values take a bit longer to propagate. + */ + do { + intel_wait_for_vblank(dev_priv, intel_crtc->pipe); + if (is_edp(intel_dp)) + usleep_range(20000, 25000); + + if (drm_dp_dpcd_read(&intel_dp->aux, DP_TEST_CRC_R_CR, + crc, 6) < 0) { + ret = -EIO; + goto stop; + } + + if (memcmp(old_crc, crc, 6) == 0) { + ret = 0; + goto stop; + } else { + memcpy(old_crc, crc, 6); + } + } while (--attempts); + DRM_DEBUG_KMS("Failed to get CRC after 6 attempts.\n"); + ret = -ETIMEDOUT; stop: intel_dp_sink_crc_stop(intel_dp); return ret;