From mboxrd@z Thu Jan 1 00:00:00 1970 From: Todd Previte Subject: [PATCH 04/10] drm/i915: Add a delay in Displayport AUX transactions for compliance testing Date: Thu, 9 Oct 2014 08:38:04 -0700 Message-ID: <1412869090-48010-5-git-send-email-tprevite@gmail.com> References: <1412869090-48010-1-git-send-email-tprevite@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from mail-yh0-f49.google.com (mail-yh0-f49.google.com [209.85.213.49]) by gabe.freedesktop.org (Postfix) with ESMTP id 8865B6E382 for ; Thu, 9 Oct 2014 08:38:49 -0700 (PDT) Received: by mail-yh0-f49.google.com with SMTP id a41so845533yho.8 for ; Thu, 09 Oct 2014 08:38:49 -0700 (PDT) In-Reply-To: <1412869090-48010-1-git-send-email-tprevite@gmail.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: intel-gfx-bounces@lists.freedesktop.org Sender: "Intel-gfx" To: intel-gfx@lists.freedesktop.org List-Id: intel-gfx@lists.freedesktop.org The Displayport Link Layer Compliance Testing Specification 1.2 rev 1.1 specifies that repeated AUX transactions after a failure (no response / invalid response) must have a minimum delay of 400us before the resend can occur. Tests 4.2.1.1 and 4.2.1.2 are two tests that require this specifically. Signed-off-by: Todd Previte --- drivers/gpu/drm/i915/intel_dp.c | 7 ++++++- 1 file changed, 6 insertions(+), 1 deletion(-) diff --git a/drivers/gpu/drm/i915/intel_dp.c b/drivers/gpu/drm/i915/intel_dp.c index 952dfa3..a7acc61 100644 --- a/drivers/gpu/drm/i915/intel_dp.c +++ b/drivers/gpu/drm/i915/intel_dp.c @@ -799,9 +799,14 @@ intel_dp_aux_ch(struct intel_dp *intel_dp, DP_AUX_CH_CTL_TIME_OUT_ERROR | DP_AUX_CH_CTL_RECEIVE_ERROR); + /* DP compliance requires 400us delay for errors + and timeouts (DP CTS 1.2 Core Rev 1.1, 4.2.1.1 + & 4.2.1.2) */ if (status & (DP_AUX_CH_CTL_TIME_OUT_ERROR | - DP_AUX_CH_CTL_RECEIVE_ERROR)) + DP_AUX_CH_CTL_RECEIVE_ERROR)) { + udelay(400); continue; + } if (status & DP_AUX_CH_CTL_DONE) break; } -- 1.9.1