From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753437AbeCEWYI (ORCPT ); Mon, 5 Mar 2018 17:24:08 -0500 Received: from bhuna.collabora.co.uk ([46.235.227.227]:37406 "EHLO bhuna.collabora.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753393AbeCEWYG (ORCPT ); Mon, 5 Mar 2018 17:24:06 -0500 From: Enric Balletbo i Serra To: architt@codeaurora.org, inki.dae@samsung.com, thierry.reding@gmail.com, hjc@rock-chips.com, seanpaul@chromium.org, airlied@linux.ie, tfiga@chromium.org, heiko@sntech.de Cc: hshi@chromium.org, wzz@rock-chips.com, hl@rock-chips.com, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, dianders@chromium.org, linux-rockchip@lists.infradead.org, orjan.eide@arm.com, m.szyprowski@samsung.com, =?UTF-8?q?St=C3=A9phane=20Marchesin?= , Enric Balletbo i Serra Subject: [PATCH v4 13/38] drm/bridge: analogix_dp: Wait for HPD signal before configuring link Date: Mon, 5 Mar 2018 23:23:05 +0100 Message-Id: <20180305222324.5872-14-enric.balletbo@collabora.com> X-Mailer: git-send-email 2.16.1 In-Reply-To: <20180305222324.5872-1-enric.balletbo@collabora.com> References: <20180305222324.5872-1-enric.balletbo@collabora.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 Signed-off-by: Enric Balletbo i Serra --- 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 c81733b8185e..92fb9a072cb6 100644 --- a/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c +++ b/drivers/gpu/drm/bridge/analogix/analogix_dp_core.c @@ -1169,6 +1169,17 @@ 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; -- 2.16.1