| Message ID | 20220627080341.5087-8-rex-bc.chen@mediatek.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | drm/mediatek: Add MT8195 DisplayPort driver | expand |
Il 27/06/22 10:03, Bo-Chen Chen ha scritto: > From: Jitao Shi <jitao.shi@mediatek.com> > > 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 <rex-bc.chen@mediatek.com> > Reviewed-by: Rex-BC Chen <rex-bc.chen@mediatek.com> > Signed-off-by: Jitao Shi <jitao.shi@mediatek.com> > Signed-off-by: Guillaume Ranquet <granquet@baylibre.com> > Signed-off-by: Bo-Chen Chen <rex-bc.chen@mediatek.com> Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
diff --git a/drivers/gpu/drm/mediatek/mtk_dp.c b/drivers/gpu/drm/mediatek/mtk_dp.c index 1697c61462b7..40771ac318e7 100644 --- a/drivers/gpu/drm/mediatek/mtk_dp.c +++ b/drivers/gpu/drm/mediatek/mtk_dp.c @@ -114,6 +114,8 @@ struct mtk_dp { bool has_fec; struct drm_connector *conn; + bool need_debounce; + struct timer_list debounce_timer; }; static struct regmap_config mtk_dp_regmap_config = { @@ -1629,6 +1631,9 @@ 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); + dev_info(mtk_dp->dev, "drm_helper_hpd_irq_event\n"); drm_helper_hpd_irq_event(mtk_dp->bridge.dev); @@ -1714,6 +1719,12 @@ 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; } @@ -2175,6 +2186,13 @@ 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; @@ -2252,6 +2270,9 @@ 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); @@ -2264,6 +2285,7 @@ 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);