| Message ID | 20220901044149.16782-10-rex-bc.chen@mediatek.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Add MT8195 DisplayPort driver | expand |
Hi, Bo-Chen: On Thu, 2022-09-01 at 12:41 +0800, Bo-Chen Chen wrote: > 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) Reviewed-by: CK Hu <ck.hu@mediatek.com> > > 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> > --- > 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); >
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);