From patchwork Tue May 28 08:27:37 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Tomi Valkeinen X-Patchwork-Id: 10964151 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 87F3D933 for ; Tue, 28 May 2019 08:29:01 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 7996C286AC for ; Tue, 28 May 2019 08:29:01 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 6D732286BE; Tue, 28 May 2019 08:29:01 +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=-5.2 required=2.0 tests=BAYES_00,MAILING_LIST_MULTI, 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 1E3C0286AC for ; Tue, 28 May 2019 08:29:01 +0000 (UTC) Received: from gabe.freedesktop.org (localhost [127.0.0.1]) by gabe.freedesktop.org (Postfix) with ESMTP id 6D76289CAF; Tue, 28 May 2019 08:28:56 +0000 (UTC) X-Original-To: dri-devel@lists.freedesktop.org Delivered-To: dri-devel@lists.freedesktop.org Received: from fllv0015.ext.ti.com (fllv0015.ext.ti.com [198.47.19.141]) by gabe.freedesktop.org (Postfix) with ESMTPS id 863C989CF9 for ; Tue, 28 May 2019 08:28:41 +0000 (UTC) Received: from lelv0265.itg.ti.com ([10.180.67.224]) by fllv0015.ext.ti.com (8.15.2/8.15.2) with ESMTP id x4S8Sc69125286; Tue, 28 May 2019 03:28:38 -0500 Received: from DFLE110.ent.ti.com (dfle110.ent.ti.com [10.64.6.31]) by lelv0265.itg.ti.com (8.15.2/8.15.2) with ESMTPS id x4S8SbQE083025 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=FAIL); Tue, 28 May 2019 03:28:37 -0500 Received: from DFLE112.ent.ti.com (10.64.6.33) by DFLE110.ent.ti.com (10.64.6.31) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.1713.5; Tue, 28 May 2019 03:28:37 -0500 Received: from lelv0327.itg.ti.com (10.180.67.183) by DFLE112.ent.ti.com (10.64.6.33) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA256_P256) id 15.1.1713.5 via Frontend Transport; Tue, 28 May 2019 03:28:37 -0500 Received: from deskari.ti.com (ileax41-snat.itg.ti.com [10.172.224.153]) by lelv0327.itg.ti.com (8.15.2/8.15.2) with ESMTP id x4S8Rxui125039; Tue, 28 May 2019 03:28:35 -0500 From: Tomi Valkeinen To: , Andrzej Hajda , Laurent Pinchart , Lucas Stach , Andrey Gusakov , Philipp Zabel , Andrey Smirnov , Peter Ujfalusi , Jyri Sarha , Benoit Parrot Subject: [PATCHv4 14/24] drm/bridge: tc358767: use more reliable seq when finishing LT Date: Tue, 28 May 2019 11:27:37 +0300 Message-ID: <20190528082747.3631-15-tomi.valkeinen@ti.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20190528082747.3631-1-tomi.valkeinen@ti.com> References: <20190528082747.3631-1-tomi.valkeinen@ti.com> MIME-Version: 1.0 X-EXCLAIMER-MD-CONFIG: e1e8a2fd-e40a-4ac6-ac9b-f7e9cc9ee180 X-Mailman-Original-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ti.com; s=ti-com-17Q1; t=1559032118; bh=I0qHcVhPYKdpjSqR6xuKYqzFyr4QxWqd0Vb32SyYoX8=; h=From:To:CC:Subject:Date:In-Reply-To:References; b=XmQ9/HudenOGCTnrHdL9qC8wL9XLnl5vizfg2cXITDrA6ZvAtaG85o0mzfPHMhQFD zSvTd+lBvQcSMszkPDPdSl87Ce1trjIqvarJargsiE9dtbkcKS3l3pckgGEwRoWEMx Y/u5esZXyEdUU0HkgS2Ni1FJpt3y3UbKietcgeOU= X-BeenThere: dri-devel@lists.freedesktop.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Direct Rendering Infrastructure - Development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Tomi Valkeinen Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" X-Virus-Scanned: ClamAV using ClamSMTP At the end of the link training, two steps have to be taken: 1) tc358767's LT mode is disabled by a write to DP0_SRCCTRL, and 2) Remove LT flag in DPCD 0x102. Toshiba's documentation tells to first write the DPCD, then modify DP0_SRCCTRL. In my testing this often causes issues, and the link disconnects right after those steps. If I reverse the steps, it works every time. There's a chance that this is DP sink specific, though, but as my testing shows this sequence to be much more reliable, let's change it. Signed-off-by: Tomi Valkeinen Reviewed-by: Andrzej Hajda --- drivers/gpu/drm/bridge/tc358767.c | 15 ++++++++++++--- 1 file changed, 12 insertions(+), 3 deletions(-) diff --git a/drivers/gpu/drm/bridge/tc358767.c b/drivers/gpu/drm/bridge/tc358767.c index a60a2e65e468..40f3efcade50 100644 --- a/drivers/gpu/drm/bridge/tc358767.c +++ b/drivers/gpu/drm/bridge/tc358767.c @@ -961,6 +961,18 @@ static int tc_main_link_enable(struct tc_data *tc) if (ret) goto err; + /* + * Toshiba's documentation suggests to first clear DPCD 0x102, then + * clear the training pattern bit in DP0_SRCCTRL. Testing shows + * that the link sometimes drops if those steps are done in that order, + * but if the steps are done in reverse order, the link stays up. + * + * So we do the steps differently than documented here. + */ + + /* Clear Training Pattern, set AutoCorrect Mode = 1 */ + tc_write(DP0_SRCCTRL, tc_srcctrl(tc) | DP0_SRCCTRL_AUTOCORRECT); + /* Clear DPCD 0x102 */ /* Note: Can Not use DP0_SNKLTCTRL (0x06E4) short cut */ tmp[0] = tc->link.scrambler_dis ? DP_LINK_SCRAMBLING_DISABLE : 0x00; @@ -968,9 +980,6 @@ static int tc_main_link_enable(struct tc_data *tc) if (ret < 0) goto err_dpcd_write; - /* Clear Training Pattern, set AutoCorrect Mode = 1 */ - tc_write(DP0_SRCCTRL, tc_srcctrl(tc) | DP0_SRCCTRL_AUTOCORRECT); - /* Wait */ timeout = 100; do {