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 8E93EC43334 for ; Tue, 26 Jul 2022 10:07:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233025AbiGZKHG (ORCPT ); Tue, 26 Jul 2022 06:07:06 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39654 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232909AbiGZKHE (ORCPT ); Tue, 26 Jul 2022 06:07:04 -0400 Received: from mailgw01.mediatek.com (unknown [60.244.123.138]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 5453864F9; Tue, 26 Jul 2022 03:07:00 -0700 (PDT) X-UUID: d8449a038d6e4e6797faf78e8f294378-20220726 X-CID-P-RULE: Release_Ham X-CID-O-INFO: VERSION:1.1.8,REQID:81a6d707-a1c8-4a0a-980b-7b1c2322e53f,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:7ab00fee-db04-4499-9fdf-04ef44b9468c,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: d8449a038d6e4e6797faf78e8f294378-20220726 Received: from mtkmbs10n2.mediatek.inc [(172.21.101.183)] by mailgw01.mediatek.com (envelope-from ) (Generic MTA with TLSv1.2 ECDHE-RSA-AES256-GCM-SHA384 256/256) with ESMTP id 1403125518; Tue, 26 Jul 2022 18:06:53 +0800 Received: from mtkmbs11n2.mediatek.inc (172.21.101.187) by mtkmbs11n2.mediatek.inc (172.21.101.187) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.792.15; Tue, 26 Jul 2022 18:06:51 +0800 Received: from mtksdccf07 (172.21.84.99) by mtkmbs11n2.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.2.792.15 via Frontend Transport; Tue, 26 Jul 2022 18:06:51 +0800 Message-ID: Subject: Re: [PATCH v14 05/10] drm/mediatek: Add MT8195 Embedded DisplayPort driver From: Rex-BC Chen To: CK Hu , "chunkuang.hu@kernel.org" , "p.zabel@pengutronix.de" , "daniel@ffwll.ch" , "robh+dt@kernel.org" , "krzysztof.kozlowski+dt@linaro.org" , "mripard@kernel.org" , "tzimmermann@suse.de" , "matthias.bgg@gmail.com" , "deller@gmx.de" , "airlied@linux.ie" CC: "msp@baylibre.com" , "granquet@baylibre.com" , "Jitao Shi =?UTF-8?Q?=28=E7=9F=B3=E8=AE=B0=E6=B6=9B=29?=" , "wenst@chromium.org" , "angelogioacchino.delregno@collabora.com" , "LiangXu Xu =?UTF-8?Q?=28=E5=BE=90=E4=BA=AE=29?=" , "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-fbdev@vger.kernel.org" , Project_Global_Chrome_Upstream_Group Date: Tue, 26 Jul 2022 18:06:50 +0800 In-Reply-To: <80f223c8ecf262a62feb047d39b9ea2d8655fd14.camel@mediatek.com> References: <20220712111223.13080-1-rex-bc.chen@mediatek.com> <20220712111223.13080-6-rex-bc.chen@mediatek.com> <378f904a445e90d65048ed07a1a55fd8c633f934.camel@mediatek.com> <9c5b85034ec77be80d771ce3a17260453f007728.camel@mediatek.com> <80f223c8ecf262a62feb047d39b9ea2d8655fd14.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-fbdev@vger.kernel.org On Tue, 2022-07-26 at 17:34 +0800, CK Hu wrote: > On Tue, 2022-07-26 at 14:42 +0800, Rex-BC Chen wrote: > > On Mon, 2022-07-25 at 17:16 +0800, CK Hu wrote: > > > 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_training(struct mtk_dp *mtk_dp) > > > > +{ > > > > + short max_retry = 50; > > > > + int ret; > > > > + > > > > + do { > > > > + ret = mtk_dp_train_start(mtk_dp); > > > > + if (!ret) > > > > + break; > > > > + else if (ret != -EAGAIN) > > > > + return ret; > > > > + } while (--max_retry); > > > > > > mtk_dp_train_start() would never return -EAGAIN, so drop this > > > while > > > loop. > > > > > > Regards, > > > CK > > > > > > > Hello CK, > > > > the function will not return -EAGAIN, but we still want to retry 50 > > times if mtk_dp_train_start() is failed. If we retry 50 times and > > it > > is > > still failed. We can confirm there are some issues for the device. > > > > I will remove the else if of -EAGAIN and keep th while loop. > > In this version, it never retry. And I believe you've tested this no- > retry version. If this no-retry version works fine, why do you insist > on retry? If you really need retry, merge this retry into > mtk_dp_train_start() because mtk_dp_train_start() have already retry. > > Regards, > CK > Hello Ck, There are many different devices we are not testing for DP devices. I think we need to keep this. This retry is for restart with init state. I think it's better to keep it here and it's more clear. I will remain the comments above, and I think it's enough. BRs, Bo-Chen > > > > BRs, > > Bo-Chen > > > > > > > > + if (!max_retry) > > > > + return -ETIMEDOUT; > > > > + > > > > + ret = mtk_dp_video_config(mtk_dp); > > > > + if (ret) > > > > + return ret; > > > > + mtk_dp_video_enable(mtk_dp, true); > > > > + > > > > + return 0; > > > > +} > > > > + > > > > > > > > > > > >