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[2a02:8440:6141:9d1b:3074:96af:9642:3]) by smtp.gmail.com with ESMTPSA id n11-20020a7bc5cb000000b003942a244f38sm8453607wmk.17.2022.05.23.03.52.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 23 May 2022 03:52:15 -0700 (PDT) From: Guillaume Ranquet To: Chun-Kuang Hu , Philipp Zabel , David Airlie , Daniel Vetter , Rob Herring , Krzysztof Kozlowski , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , Matthias Brugger , Chunfeng Yun , Kishon Vijay Abraham I , Vinod Koul , Helge Deller , CK Hu , Jitao shi Cc: Rex-BC Chen , 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 Subject: [PATCH v10 20/21] drm/mediatek: add hpd debounce Date: Mon, 23 May 2022 12:47:53 +0200 Message-Id: <20220523104758.29531-21-granquet@baylibre.com> X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220523104758.29531-1-granquet@baylibre.com> References: <20220523104758.29531-1-granquet@baylibre.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-fbdev@vger.kernel.org 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) Tested-by: Rex-BC Chen Reviewed-by: Rex-BC Chen Signed-off-by: Jitao Shi Signed-off-by: Guillaume Ranquet --- drivers/gpu/drm/mediatek/mtk_dp.c | 21 +++++++++++++++++++++ 1 file changed, 21 insertions(+) diff --git a/drivers/gpu/drm/mediatek/mtk_dp.c b/drivers/gpu/drm/mediatek/mtk_dp.c index 4789853ec5ff..c056bc3ca9f6 100644 --- a/drivers/gpu/drm/mediatek/mtk_dp.c +++ b/drivers/gpu/drm/mediatek/mtk_dp.c @@ -154,6 +154,8 @@ struct mtk_dp { struct mutex dp_lock; struct drm_connector *conn; + bool need_debounce; + struct timer_list debounce_timer; }; static struct regmap_config mtk_dp_regmap_config = { @@ -1970,6 +1972,9 @@ static irqreturn_t mtk_dp_hpd_event_thread(int hpd, void *dev) if (event < 0) return IRQ_HANDLED; + if (mtk_dp->need_debounce && mtk_dp->train_info.cable_plugged_in) + msleep(100); + if (mtk_dp->drm_dev) { dev_info(mtk_dp->dev, "drm_helper_hpd_irq_event\n"); drm_helper_hpd_irq_event(mtk_dp->bridge.dev); @@ -2047,6 +2052,11 @@ static irqreturn_t mtk_dp_hpd_isr_handler(struct mtk_dp *mtk_dp) } train_info->cable_state_change = true; + if (!train_info->cable_plugged_in) { + mod_timer(&mtk_dp->debounce_timer, jiffies + msecs_to_jiffies(100) - 1); + mtk_dp->need_debounce = false; + } + return IRQ_WAKE_THREAD; } @@ -2474,6 +2484,13 @@ 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; @@ -2547,6 +2564,9 @@ static int mtk_dp_probe(struct platform_device *pdev) else mtk_dp->bridge.type = DRM_MODE_CONNECTOR_DisplayPort; + 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); @@ -2559,6 +2579,7 @@ static int mtk_dp_remove(struct platform_device *pdev) platform_device_unregister(mtk_dp->phy_dev); mtk_dp_video_mute(mtk_dp, true); + del_timer_sync(&mtk_dp->debounce_timer); pm_runtime_disable(&pdev->dev);