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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 9468BECAAD5 for ; Fri, 2 Sep 2022 09:04:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Date:CC:To:From:Subject:Message-ID:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=4s81Z/8nFHCZQka7/mY991xYpSOXAd+VNh7HxWiDkmE=; b=LDtr47e5145BWG sQT/uYRrewz0cpvGpSn8xNgElFpW1Mz223qWiuC59gktlZ7N2SfDZTpZr8ica1GD4OcMgFna5Q+pw rnlulNB3hedcXJE+QwUnJ6ECNgiLfEVnZu6LSE2X0i7E9a5Q8HnpalHupi1tsji0wSPypCrTHiuDz MfxwQIL90dviztQj0ciUtZvGtAl1E779YNArqnaUD1Zxcb6ikCFk3yi8cCaZsvURV/yzqdoSVDBYX zyrSVH8TLxtRweVTZPECk4d1LXK9ZHViHVk4OgNKx3+Zd/zPxJIlCEcp557SIL8VszpB6BCu0VpVx cFeuHVj1fvAj8/MmJdmA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1oU2aY-002Gms-CN; Fri, 02 Sep 2022 09:03:46 +0000 Received: from mailgw01.mediatek.com ([216.200.240.184]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1oU2aT-002Gjg-U1; Fri, 02 Sep 2022 09:03:43 +0000 X-UUID: c86ba494633440aeaab7ff116d4516b2-20220902 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=mediatek.com; s=dk; h=Content-Transfer-Encoding:MIME-Version:Content-Type:References:In-Reply-To:Date:CC:To:From:Subject:Message-ID; bh=pmqfNQ1rpSeqmCSW/up+Y4xTBOUZWeAGJ2HY4TQtBp0=; b=e13T1U9lGIdmAkrOiO4XQDMmBRxykHPpm9sdzfEz+Jf+pxwYKCZkEnciIbPSd8ka34sPW5Pm9gOcYq4LS0zIjvXfZGrmvAxCPCtjZ1JGJpovhtidP3IlS670Zf1r4o5GfGXVfvVLWnw9Lew4sZI9j11CQDu3udnPV/+MTzaZocI=; X-CID-P-RULE: Release_Ham X-CID-O-INFO: VERSION:1.1.10,REQID:480ede2e-d83d-43d6-a52c-a6086be01f71,OB:0,L OB:0,IP:0,URL:0,TC:0,Content:0,EDM:0,RT:0,SF:0,FILE:0,BULK:0,RULE:Release_ Ham,ACTION:release,TS:0 X-CID-META: VersionHash:84eae18,CLOUDID:5b956756-e800-47dc-8adf-0c936acf4f1b,C OID:IGNORED,Recheck:0,SF:nil,TC:nil,Content:0,EDM:-3,IP:nil,URL:11|1,File: nil,Bulk:nil,QS:nil,BEC:nil,COL:0 X-UUID: c86ba494633440aeaab7ff116d4516b2-20220902 Received: from mtkmbs11n1.mediatek.inc [(172.21.101.185)] by mailgw01.mediatek.com (envelope-from ) (musrelay.mediatek.com ESMTP with TLSv1.2 ECDHE-RSA-AES256-GCM-SHA384 256/256) with ESMTP id 1209032250; Fri, 02 Sep 2022 02:03:35 -0700 Received: from mtkmbs11n1.mediatek.inc (172.21.101.186) by mtkmbs10n1.mediatek.inc (172.21.101.34) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.792.15; Fri, 2 Sep 2022 16:12:59 +0800 Received: from mtksdccf07 (172.21.84.99) by mtkmbs11n1.mediatek.inc (172.21.101.73) with Microsoft SMTP Server id 15.2.792.15 via Frontend Transport; Fri, 2 Sep 2022 16:12:59 +0800 Message-ID: Subject: Re: [PATCH v17 09/10] drm/mediatek: dp: Add hpd debounce From: CK Hu To: Bo-Chen Chen , , , , , , , , , , CC: , , , , , , , , , , , , Date: Fri, 2 Sep 2022 16:12:58 +0800 In-Reply-To: <20220901044149.16782-10-rex-bc.chen@mediatek.com> References: <20220901044149.16782-1-rex-bc.chen@mediatek.com> <20220901044149.16782-10-rex-bc.chen@mediatek.com> X-Mailer: Evolution 3.28.5-0ubuntu0.18.04.2 MIME-Version: 1.0 X-MTK: N X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220902_020342_009505_9AACDC43 X-CRM114-Status: GOOD ( 31.70 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi, Bo-Chen: On Thu, 2022-09-01 at 12:41 +0800, Bo-Chen Chen wrote: > From: Jitao Shi > > From the DP spec 1.4a chapter 3.3, upstream devices should implement > HPD signal de-bouncing on an external connection. > A period of 100ms should be used to detect an HPD connect event. > To cover these cases, HPD de-bounce should be implemented only after > HPD low has been detected for at least 100ms. > > Therefore, > 1. If HPD is low (which means plugging out) for longer than 100ms: > we need to do de-bouncing (which means we need to wait for 100ms). > 2. If HPD low is for less than 100ms: > we don't need to care about the de-bouncing. > > In this patch, we start a 100ms timer and use a need_debounce boolean > to implement the feature. > > Two cases when HPD is high: > 1. If the timer is expired (>100ms): > - need_debounce is true. > - When HPD high (plugging event comes), need_debounce will be true > and then we need to do de-bouncing (wait for 100ms). > 2. If the timer is not expired (<100ms): > - need_debounce is false. > - When HPD high (plugging event comes), need_debounce will be > false > and no need to do de-bouncing. > > HPD_______ __________________ > | |<- 100ms -> > |____________| > <- 100ms -> > > Without HPD de-bouncing, USB-C to HDMI Adapaters will not be > detected. > > The change has been successfully tested with the following devices: > - Dell Adapter - USB-C to HDMI > - Acer 1in1 HDMI dongle > - Ugreen 1in1 HDMI dongle > - innowatt HDMI + USB3 hub > - Acer 2in1 HDMI dongle > - Apple 3in1 HDMI dongle (A2119) > - J5Create 3in1 HDMI dongle (JAC379) Reviewed-by: CK Hu > > Tested-by: Rex-BC Chen > Reviewed-by: Rex-BC Chen > Signed-off-by: Jitao Shi > Signed-off-by: Guillaume Ranquet > Signed-off-by: Bo-Chen Chen > Reviewed-by: AngeloGioacchino Del Regno < > angelogioacchino.delregno@collabora.com> > --- > drivers/gpu/drm/mediatek/mtk_dp.c | 25 ++++++++++++++++++++++++- > 1 file changed, 24 insertions(+), 1 deletion(-) > > diff --git a/drivers/gpu/drm/mediatek/mtk_dp.c > b/drivers/gpu/drm/mediatek/mtk_dp.c > index 11a94927c0d0..dd34dae417e5 100644 > --- a/drivers/gpu/drm/mediatek/mtk_dp.c > +++ b/drivers/gpu/drm/mediatek/mtk_dp.c > @@ -87,6 +87,7 @@ struct mtk_dp_efuse_fmt { > > struct mtk_dp { > bool enabled; > + bool need_debounce; > u8 max_lanes; > u8 max_linkrate; > u8 rx_cap[DP_RECEIVER_CAP_SIZE]; > @@ -109,6 +110,7 @@ struct mtk_dp { > struct platform_device *phy_dev; > struct phy *phy; > struct regmap *regs; > + struct timer_list debounce_timer; > }; > > struct mtk_dp_data { > @@ -1475,14 +1477,24 @@ static irqreturn_t > mtk_dp_hpd_event_thread(int hpd, void *dev) > unsigned long flags; > u32 status; > > + if (mtk_dp->need_debounce && mtk_dp- > >train_info.cable_plugged_in) > + msleep(100); > + > spin_lock_irqsave(&mtk_dp->irq_thread_lock, flags); > status = mtk_dp->irq_thread_handle; > mtk_dp->irq_thread_handle = 0; > spin_unlock_irqrestore(&mtk_dp->irq_thread_lock, flags); > > - if (status & MTK_DP_THREAD_CABLE_STATE_CHG) > + if (status & MTK_DP_THREAD_CABLE_STATE_CHG) { > drm_helper_hpd_irq_event(mtk_dp->bridge.dev); > > + if (!mtk_dp->train_info.cable_plugged_in) { > + mtk_dp->need_debounce = false; > + mod_timer(&mtk_dp->debounce_timer, > + jiffies + msecs_to_jiffies(100) - 1); > + } > + } > + > if (status & MTK_DP_THREAD_HPD_EVENT) > dev_dbg(mtk_dp->dev, "Receive IRQ from sink > devices\n"); > > @@ -1996,6 +2008,13 @@ static const struct drm_bridge_funcs > mtk_dp_bridge_funcs = { > .detect = mtk_dp_bdg_detect, > }; > > +static void mtk_dp_debounce_timer(struct timer_list *t) > +{ > + struct mtk_dp *mtk_dp = from_timer(mtk_dp, t, debounce_timer); > + > + mtk_dp->need_debounce = true; > +} > + > static int mtk_dp_probe(struct platform_device *pdev) > { > struct mtk_dp *mtk_dp; > @@ -2069,6 +2088,9 @@ static int mtk_dp_probe(struct platform_device > *pdev) > > drm_bridge_add(&mtk_dp->bridge); > > + mtk_dp->need_debounce = true; > + timer_setup(&mtk_dp->debounce_timer, mtk_dp_debounce_timer, 0); > + > pm_runtime_enable(dev); > pm_runtime_get_sync(dev); > > @@ -2081,6 +2103,7 @@ static int mtk_dp_remove(struct platform_device > *pdev) > > pm_runtime_put(&pdev->dev); > pm_runtime_disable(&pdev->dev); > + del_timer_sync(&mtk_dp->debounce_timer); > drm_bridge_remove(&mtk_dp->bridge); > platform_device_unregister(mtk_dp->phy_dev); > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel