Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S967754AbeAOR0T (ORCPT + 1 other); Mon, 15 Jan 2018 12:26:19 -0500 Received: from bhuna.collabora.co.uk ([46.235.227.227]:57524 "EHLO bhuna.collabora.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S966596AbeAORRE (ORCPT ); Mon, 15 Jan 2018 12:17:04 -0500 From: Thierry Escande To: Archit Taneja , Inki Dae , Thierry Reding , Sandy Huang , Sean Paul , David Airlie Cc: Tomasz Figa , Haixia Shi , =?UTF-8?q?=C3=98rjan=20Eide?= , zain wang , Yakir Yang , Lin Huang , Douglas Anderson , Mark Yao , linux-kernel@vger.kernel.org, linux-rockchip@lists.infradead.org, dri-devel@lists.freedesktop.org Subject: [PATCH 17/40] drm/bridge: analogix_dp: Wait for HPD signal before configuring link Date: Mon, 15 Jan 2018 18:15:51 +0100 Message-Id: <20180115171614.14474-18-thierry.escande@collabora.com> X-Mailer: git-send-email 2.14.1 In-Reply-To: <20180115171614.14474-1-thierry.escande@collabora.com> References: <20180115171614.14474-1-thierry.escande@collabora.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Type: text/plain; charset = "utf-8" Content-Transfert-Encoding: 8bit Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: From: zain wang According to DP spec v1.3 chap 3.5.1.2 Link Training, Link Policy Maker must first detect that the HPD signal is asserted high by the Downstream Device before establishing a link with it. Cc: Stéphane Marchesin Signed-off-by: zain wang Signed-off-by: Sean Paul Signed-off-by: Thierry Escande --- drivers/gpu/drm/bridge/analogix/analogix_dp_core.c | 11 +++++++++++ 1 file changed, 11 insertions(+) diff --git a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c index ba2506e17f6d..c940a5bb80ac 100644 --- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c +++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c @@ -1170,6 +1170,17 @@ static int analogix_dp_set_bridge(struct analogix_dp_device *dp) if (ret) goto out_dp_init; + /* + * According to DP spec v1.3 chap 3.5.1.2 Link Training, + * We should first make sure the HPD signal is asserted high by device + * when we want to establish a link with it. + */ + ret = analogix_dp_detect_hpd(dp); + if (ret) { + DRM_ERROR("failed to get hpd single ret = %d\n", ret); + goto out_dp_init; + } + ret = analogix_dp_commit(dp); if (ret) goto out_dp_init; -- 2.14.1