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 A4EDAC43334 for ; Wed, 8 Jun 2022 05:28:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230308AbiFHF2A (ORCPT ); Wed, 8 Jun 2022 01:28:00 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54212 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233689AbiFHF1g (ORCPT ); Wed, 8 Jun 2022 01:27:36 -0400 Received: from mailgw02.mediatek.com (unknown [210.61.82.184]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C12E7188E8B; Tue, 7 Jun 2022 19:44:08 -0700 (PDT) X-UUID: 5d9d18f1fbb24968ad8220c6c8b67a62-20220608 X-CID-P-RULE: Release_Ham X-CID-O-INFO: VERSION:1.1.5,REQID:5582af41-9384-4a7e-976b-08a1a2fa5e80,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:2a19b09,CLOUDID:56ac8f7e-c8dc-403a-96e8-6237210dceee,C OID:IGNORED,Recheck:0,SF:nil,TC:nil,Content:0,EDM:-3,IP:nil,URL:0,File:nil ,QS:0,BEC:nil X-UUID: 5d9d18f1fbb24968ad8220c6c8b67a62-20220608 Received: from mtkmbs11n1.mediatek.inc [(172.21.101.185)] by mailgw02.mediatek.com (envelope-from ) (Generic MTA with TLSv1.2 ECDHE-RSA-AES256-GCM-SHA384 256/256) with ESMTP id 246062154; Wed, 08 Jun 2022 10:44:03 +0800 Received: from mtkmbs11n1.mediatek.inc (172.21.101.185) by mtkmbs11n1.mediatek.inc (172.21.101.185) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.792.3; Wed, 8 Jun 2022 10:44:01 +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; Wed, 8 Jun 2022 10:44:01 +0800 Message-ID: <79bea587e20de842d48dcb2e1da19e276f9d635b.camel@mediatek.com> Subject: Re: [PATCH v10 18/21] drm/mediatek: Add mt8195 Embedded DisplayPort driver From: CK Hu To: Rex-BC Chen , Guillaume Ranquet , Chun-Kuang Hu , "Philipp Zabel" , David Airlie , "Daniel Vetter" , Rob Herring , "Krzysztof Kozlowski" , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , Matthias Brugger , Chunfeng Yun =?UTF-8?Q?=28=E4=BA=91=E6=98=A5=E5=B3=B0=29?= , Kishon Vijay Abraham I , Vinod Koul , Helge Deller , Jitao Shi =?UTF-8?Q?=28=E7=9F=B3=E8=AE=B0=E6=B6=9B=29?= CC: Markus Schneider-Pargmann , "dri-devel@lists.freedesktop.org" , "linux-mediatek@lists.infradead.org" , "devicetree@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "linux-phy@lists.infradead.org" , "linux-fbdev@vger.kernel.org" Date: Wed, 8 Jun 2022 10:44:01 +0800 In-Reply-To: <4329859ca11c13e7f6a9951b01a779fc391f029b.camel@mediatek.com> References: <20220523104758.29531-1-granquet@baylibre.com> <20220523104758.29531-19-granquet@baylibre.com> <4329859ca11c13e7f6a9951b01a779fc391f029b.camel@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: linux-kernel@vger.kernel.org Hi, Rex: On Tue, 2022-06-07 at 20:44 +0800, Rex-BC Chen wrote: > On Tue, 2022-06-07 at 14:44 +0800, CK Hu wrote: > > Hi, Rex: > > > > On Mon, 2022-05-23 at 12:47 +0200, Guillaume Ranquet wrote: > > > From: Markus Schneider-Pargmann > > > > > > This patch adds a 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 > > > Jason-JH.Lin . > > > > > > Signed-off-by: Markus Schneider-Pargmann > > > Signed-off-by: Guillaume Ranquet > > > --- > > > > [snip] > > > > > + > > > +static int mtk_dp_train_handler(struct mtk_dp *mtk_dp) > > > +{ > > > + bool training_done = false; > > > + short max_retry = 50; > > > + int ret = 0; > > > + > > > + do { > > > + switch (mtk_dp->train_state) { > > > + case MTK_DP_TRAIN_STATE_STARTUP: > > > > mtk_dp->train_state is initialized as MTK_DP_TRAIN_STATE_STARTUP > > even > > though HPD ISR does not exist. Does this mean HPD ISR is redundant? > > If > > HPD ISR is not redundant, create a new state > > MTK_DP_TRAIN_STATE_NONE > > for init state. > > > > Hello CK, > > I think we don't need MTK_DP_TRAIN_STATE_NONE. > Because it's "DP_TRAIN_STATE" not "DP_STATE", I think it's ok if we > start this state machine with "MTK_DP_TRAIN_STATE_STARTUP". The initial state is MTK_DP_TRAIN_STATE_STARTUP, and HPD thread would change state from MTK_DP_TRAIN_STATE_STARTUP to MTK_DP_TRAIN_STATE_STARTUP, this is redundant. So drop the state change in HPD thread. > > > > + mtk_dp_state_handler(mtk_dp); > > > + mtk_dp->train_state = > > > MTK_DP_TRAIN_STATE_CHECKCAP; > > > + break; > > > + > > > + case MTK_DP_TRAIN_STATE_CHECKCAP: > > > + if (mtk_dp_parse_capabilities(mtk_dp)) { > > > + mtk_dp->train_info.check_cap_count = 0; > > > + mtk_dp->train_state = > > > MTK_DP_TRAIN_STATE_CHECKEDID; > > > + } else { > > > + mtk_dp->train_info.check_cap_count++; > > > + > > > + if (mtk_dp->train_info.check_cap_count > > > > > > > > > > + MTK_DP_CHECK_SINK_CAP_TIMEOUT_COUNT > > > ) { > > > + mtk_dp- > > > > train_info.check_cap_count = 0; > > > > > > + mtk_dp->train_state = > > > MTK_DP_TRAIN_STATE_DPIDLE; > > > + ret = -ETIMEDOUT; > > > + } > > > + } > > > + break; > > > + > > > + case MTK_DP_TRAIN_STATE_CHECKEDID: > > > + mtk_dp->train_state = > > > MTK_DP_TRAIN_STATE_TRAINING_PRE; > > > > MTK_DP_TRAIN_STATE_CHECKEDID is a redundant state, drop it. > > > > > + break; > > > + > > > + case MTK_DP_TRAIN_STATE_TRAINING_PRE: > > > + mtk_dp_state_handler(mtk_dp); > > > + mtk_dp->train_state = > > > MTK_DP_TRAIN_STATE_TRAINING; > > > + break; > > > + > > > + case MTK_DP_TRAIN_STATE_TRAINING: > > > + ret = mtk_dp_train_start(mtk_dp); > > > + if (ret == 0) { > > > + mtk_dp_video_mute(mtk_dp, true); > > > + mtk_dp->train_state = > > > MTK_DP_TRAIN_STATE_NORMAL; > > > + mtk_dp_fec_enable(mtk_dp, mtk_dp- > > > > has_fec); > > > > > > + } else if (ret != -EAGAIN) { > > > + mtk_dp->train_state = > > > MTK_DP_TRAIN_STATE_DPIDLE; > > > + } > > > + break; > > > + case MTK_DP_TRAIN_STATE_NORMAL: > > > + mtk_dp_state_handler(mtk_dp); > > > + training_done = true; > > > + break; > > > + case MTK_DP_TRAIN_STATE_DPIDLE: > > > > When would this case happen? > > > > Regards, > > CK > > Yes, if it's disconnected if we are still training for dp. > or failed to training min spec RBR. I mean, every time state change to MTK_DP_TRAIN_STATE_DPIDLE, it would jump out of this loop and would not get into this loop, so this case would never get in. This is redundant, so remove this. Regards, CK > > BRs, > Rex > > > > > + break; > > > + default: > > > + break; > > > + } > > > + > > > + if (ret) { > > > + if (ret == -EAGAIN) > > > + continue; > > > + /* > > > + * If we get any other error number, it doesn't > > > + * make any sense to keep iterating. > > > + */ > > > + break; > > > + } > > > + } while (!training_done || --max_retry); > > > + > > > + return ret; > > > +} > > > > > >