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 605A7CCA479 for ; Thu, 7 Jul 2022 07:50:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235094AbiGGHuX (ORCPT ); Thu, 7 Jul 2022 03:50:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37830 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235079AbiGGHuW (ORCPT ); Thu, 7 Jul 2022 03:50:22 -0400 Received: from mailgw01.mediatek.com (unknown [60.244.123.138]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6FC2E28E13; Thu, 7 Jul 2022 00:50:18 -0700 (PDT) X-UUID: cb064ff2a78f4462a7ba4d2367b75615-20220707 X-CID-P-RULE: Release_Ham X-CID-O-INFO: VERSION:1.1.8,REQID:887d7773-0562-4434-9921-16d3b14add2e,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:e67bdad6-5d6d-4eaf-a635-828a3ee48b7c,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: cb064ff2a78f4462a7ba4d2367b75615-20220707 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 1268588751; Thu, 07 Jul 2022 15:50:14 +0800 Received: from mtkmbs11n2.mediatek.inc (172.21.101.187) 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, 7 Jul 2022 15:50:12 +0800 Received: from mtksdccf07 (172.21.84.99) by mtkmbs11n2.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.2.792.3 via Frontend Transport; Thu, 7 Jul 2022 15:50:12 +0800 Message-ID: Subject: Re: [PATCH v13 05/10] drm/mediatek: Add MT8195 Embedded DisplayPort driver From: CK Hu To: Bo-Chen Chen , , , , , , , , , , CC: , , , , , , , , , , , , Date: Thu, 7 Jul 2022 15:50:12 +0800 In-Reply-To: <20220701062808.18596-6-rex-bc.chen@mediatek.com> References: <20220701062808.18596-1-rex-bc.chen@mediatek.com> <20220701062808.18596-6-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: linux-kernel@vger.kernel.org Hi, Bo-Chen: On Fri, 2022-07-01 at 14:28 +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] > +/* > + * We need to handle HPD signal in eDP even though eDP is a always > connected > + * device. Besides connected status, there is another feature for > HPD signal - > + * HPD pulse: it presents an IRQ from sink devices to source devices > (Refer to > + * 5.1.4 of DP1.4 spec). > + */ > +static irqreturn_t mtk_dp_hpd_isr_handler(struct mtk_dp *mtk_dp) > +{ > + bool connected; > + bool hpd_connect_sta; > + u32 irq_status = mtk_dp_swirq_get_clear(mtk_dp) | > + mtk_dp_hwirq_get_clear(mtk_dp); > + struct mtk_dp_train_info *train_info = &mtk_dp->train_info; > + > + if (irq_status & MTK_DP_HPD_INTERRUPT) > + train_info->irq_sta.hpd_inerrupt = true; > + if (irq_status & MTK_DP_HPD_CONNECT) > + hpd_connect_sta = true; > + if (irq_status & MTK_DP_HPD_DISCONNECT) > + train_info->irq_sta.hpd_disconnect = true; hpd_disconnect is used only in this function, so let it be local variable. > + > + if (!irq_status) > + return IRQ_HANDLED; Move this to top of this function. > + > + connected = mtk_dp_plug_state(mtk_dp); > + if (connected || !train_info->cable_plugged_in) > + train_info->irq_sta.hpd_disconnect = false; The truth table of (irq_status & MTK_DP_HPD_DISCONNECT, connected, cable_plugged_in, hpd_disconnect) is 0 0 0 0 0 0 1 0 0 1 0 0 0 1 1 0 1 0 0 0 1 0 1 1 1 1 0 0 1 1 1 0 So the only case that hpd_disconnect is true is (irq_status & MTK_DP_HPD_DISCONNECT) && !connected && train_info- >cable_plugged_in) And train_info->cable_plugged_in is the previous status. The previous status is connected. And irq_status and connected is the new status. The new status is disconnected. I have a question. Why we need both irq_status and connected for new status? I think connected is enough for new status, so we could ignore irq_status. Regards, CK > + else if (!connected || train_info->cable_plugged_in) > + hpd_connect_sta = false; > + > + if (!(hpd_connect_sta || train_info->irq_sta.hpd_disconnect)) > + return IRQ_WAKE_THREAD; > + > + if (hpd_connect_sta) { > + hpd_connect_sta = false; > + train_info->cable_plugged_in = true; > + } else { > + train_info->irq_sta.hpd_disconnect = false; > + train_info->cable_plugged_in = false; > + } > + train_info->cable_state_change = true; > + > + return IRQ_WAKE_THREAD; > +} > +