From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5DCC8CCA481 for ; Thu, 14 Jul 2022 07:06:57 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233252AbiGNHG4 (ORCPT ); Thu, 14 Jul 2022 03:06:56 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45242 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229817AbiGNHG4 (ORCPT ); Thu, 14 Jul 2022 03:06:56 -0400 Received: from mailgw01.mediatek.com (unknown [60.244.123.138]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6293614099; Thu, 14 Jul 2022 00:06:54 -0700 (PDT) X-UUID: ad768e33beae4ed3887005b9df756985-20220714 X-CID-P-RULE: Release_Ham X-CID-O-INFO: VERSION:1.1.8,REQID:a03c257e-828c-4663-ae6f-f5abf8e4a931,OB:0,LO B:0,IP:0,URL:0,TC:0,Content:0,EDM:0,RT:0,SF:0,FILE:0,RULE:Release_Ham,ACTI ON:release,TS:0 X-CID-META: VersionHash:0f94e32,CLOUDID:076df532-b9e4-42b8-b28a-6364427c76bb,C OID:IGNORED,Recheck:0,SF:nil,TC:nil,Content:0,EDM:-3,IP:nil,URL:0,File:nil ,QS:nil,BEC:nil,COL:0 X-UUID: ad768e33beae4ed3887005b9df756985-20220714 Received: from mtkmbs11n2.mediatek.inc [(172.21.101.187)] by mailgw01.mediatek.com (envelope-from ) (Generic MTA with TLSv1.2 ECDHE-RSA-AES256-GCM-SHA384 256/256) with ESMTP id 1094732513; Thu, 14 Jul 2022 15:06:47 +0800 Received: from mtkmbs11n1.mediatek.inc (172.21.101.185) by mtkmbs10n2.mediatek.inc (172.21.101.183) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.792.3; Thu, 14 Jul 2022 15:06:46 +0800 Received: from mtksdccf07 (172.21.84.99) by mtkmbs11n1.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.2.792.3 via Frontend Transport; Thu, 14 Jul 2022 15:06:46 +0800 Message-ID: Subject: Re: [PATCH v14 05/10] drm/mediatek: Add MT8195 Embedded DisplayPort driver From: CK Hu To: Bo-Chen Chen , , , , , , , , , , CC: , , , , , , , , , , , , Date: Thu, 14 Jul 2022 15:06:46 +0800 In-Reply-To: <20220712111223.13080-6-rex-bc.chen@mediatek.com> References: <20220712111223.13080-1-rex-bc.chen@mediatek.com> <20220712111223.13080-6-rex-bc.chen@mediatek.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.28.5-0ubuntu0.18.04.2 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-MTK: N Precedence: bulk List-ID: X-Mailing-List: devicetree@vger.kernel.org Hi, Bo-Chen: On Tue, 2022-07-12 at 19:12 +0800, Bo-Chen Chen wrote: > From: Markus Schneider-Pargmann > > This patch adds a embedded displayport driver for the MediaTek mt8195 > SoC. > > It supports the MT8195, the embedded DisplayPort units. It offers > DisplayPort 1.4 with up to 4 lanes. > > The driver creates a child device for the phy. The child device will > never exist without the parent being active. As they are sharing a > register range, the parent passes a regmap pointer to the child so > that > both can work with the same register range. The phy driver sets > device > data that is read by the parent to get the phy device that can be > used > to control the phy properties. > > This driver is based on an initial version by > Jitao shi > > Signed-off-by: Markus Schneider-Pargmann > Signed-off-by: Guillaume Ranquet > Signed-off-by: Bo-Chen Chen > --- [snip] > + > +static int mtk_dp_train_flow(struct mtk_dp *mtk_dp, u8 > target_link_rate, > + u8 target_lane_count) > +{ > + u8 lane_adjust[2] = {}; > + bool pass_tps1 = false; > + bool pass_tps2_3 = false; > + int train_retries; > + int status_control; > + int iteration_count; > + int ret; > + u8 prev_lane_adjust; > + > + drm_dp_dpcd_writeb(&mtk_dp->aux, DP_LINK_BW_SET, > target_link_rate); > + drm_dp_dpcd_writeb(&mtk_dp->aux, DP_LANE_COUNT_SET, > + target_lane_count | > DP_LANE_COUNT_ENHANCED_FRAME_EN); > + > + if (mtk_dp->train_info.sink_ssc) > + drm_dp_dpcd_writeb(&mtk_dp->aux, DP_DOWNSPREAD_CTRL, > + DP_SPREAD_AMP_0_5); > + > + train_retries = 0; > + status_control = 0; > + iteration_count = 1; > + prev_lane_adjust = 0xFF; > + > + mtk_dp_set_lanes(mtk_dp, target_lane_count / 2); > + ret = mtk_dp_phy_configure(mtk_dp, target_link_rate, > target_lane_count); > + if (ret) > + return ret; > + > + dev_dbg(mtk_dp->dev, > + "Link train target_link_rate = 0x%x, target_lane_count > = 0x%x\n", > + target_link_rate, target_lane_count); > + > + do { > + train_retries++; > + if (!mtk_dp->train_info.cable_plugged_in) > + return -ENODEV; > + > + if (!pass_tps1) { > + ret = mtk_dp_train_tps_1(mtk_dp, > target_lane_count, > + &iteration_count, > lane_adjust, > + &status_control, > + &prev_lane_adjust); > + if (!ret) { > + pass_tps1 = true; > + train_retries = 0; > + } else if (ret == -EINVAL) { > + break; > + } > + } else { > + ret = mtk_dp_train_tps_2_3(mtk_dp, > target_link_rate, > + target_lane_count, > + &iteration_count, > + lane_adjust, > &status_control, > + &prev_lane_adjust); > + if (!ret) { > + pass_tps2_3 = true; > + break; > + } else if (ret == -EINVAL) { > + break; > + } > + } > + > + drm_dp_dpcd_read(&mtk_dp->aux, > DP_ADJUST_REQUEST_LANE0_1, > + lane_adjust, sizeof(lane_adjust)); > + mtk_dp_train_update_swing_pre(mtk_dp, > target_lane_count, > + lane_adjust); > + } while (train_retries < MTK_DP_TRAIN_RETRY_LIMIT && > + iteration_count < MTK_DP_TRAIN_MAX_ITERATIONS); train_retries and iteration_count are the same thing, so keep one and drop another one. Regards, CK > + > + drm_dp_dpcd_writeb(&mtk_dp->aux, DP_TRAINING_PATTERN_SET, > + DP_TRAINING_PATTERN_DISABLE); > + mtk_dp_train_set_pattern(mtk_dp, 0); > + > + if (!pass_tps2_3) > + return -ETIMEDOUT; > + > + mtk_dp->train_info.link_rate = target_link_rate; > + mtk_dp->train_info.lane_count = target_lane_count; > + > + mtk_dp_training_set_scramble(mtk_dp, true); > + > + drm_dp_dpcd_writeb(&mtk_dp->aux, DP_LANE_COUNT_SET, > + target_lane_count | > + DP_LANE_COUNT_ENHANCED_FRAME_EN); > + mtk_dp_set_enhanced_frame_mode(mtk_dp, true); > + > + return ret; > +} > +