drm/exynos: Debounce HDMI hotplug interrupts

This patch debounces hotplug interrupts generated by the HDMI hotplug
gpio. The reason this is needed is that we get multiple (5) interrupts
every time a monitor is inserted which causes us to needlessly enable
and disable the IP block.

Signed-off-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Rahul Sharma <Rahul.Sharma@samsung.com>
Signed-off-by: Inki Dae <inki.dae@samsung.com>

1 files changed, 21 insertions, 2 deletions

diff --git a/drivers/gpu/drm/exynos/exynos_hdmi.c b/drivers/gpu/drm/exynos/exynos_hdmi.c
index c7329d97413a..73a7acb1283c 100644
--- a/drivers/gpu/drm/exynos/exynos_hdmi.c
+++ b/drivers/gpu/drm/exynos/exynos_hdmi.c
@@ -50,6 +50,8 @@
 #define get_hdmi_display(dev)   platform_get_drvdata(to_platform_device(dev))
 #define ctx_from_connector(c)   container_of(c, struct hdmi_context, connector)
 
+#define HOTPLUG_DEBOUNCE_MS             1100
+
 /* AVI header and aspect ratio */
 #define HDMI_AVI_VERSION                0x02
 #define HDMI_AVI_LENGTH         0x0D
@@ -187,6 +189,7 @@ struct hdmi_context {
 
         void __iomem                    *regs;
         int                             irq;
+        struct delayed_work             hotplug_work;
 
         struct i2c_adapter              *ddc_adpt;
         struct i2c_client               *hdmiphy_port;
@@ -1857,6 +1860,8 @@ static void hdmi_poweroff(struct exynos_drm_display *display)
 
         hdmiphy_poweroff(hdata);
 
+        cancel_delayed_work(&hdata->hotplug_work);
+
         clk_disable_unprepare(res->sclk_hdmi);
         clk_disable_unprepare(res->hdmi);
         clk_disable_unprepare(res->hdmiphy);
@@ -1903,9 +1908,11 @@ static struct exynos_drm_display hdmi_display = {
         .ops = &hdmi_display_ops,
 };
 
-static irqreturn_t hdmi_irq_thread(int irq, void *arg)
+static void hdmi_hotplug_work_func(struct work_struct *work)
 {
-        struct hdmi_context *hdata = arg;
+        struct hdmi_context *hdata;
+
+        hdata = container_of(work, struct hdmi_context, hotplug_work.work);
 
         mutex_lock(&hdata->hdmi_mutex);
         hdata->hpd = gpio_get_value(hdata->hpd_gpio);
@@ -1913,6 +1920,14 @@ static irqreturn_t hdmi_irq_thread(int irq, void *arg)
 
         if (hdata->drm_dev)
                 drm_helper_hpd_irq_event(hdata->drm_dev);
+}
+
+static irqreturn_t hdmi_irq_thread(int irq, void *arg)
+{
+        struct hdmi_context *hdata = arg;
+
+        mod_delayed_work(system_wq, &hdata->hotplug_work,
+                        msecs_to_jiffies(HOTPLUG_DEBOUNCE_MS));
 
         return IRQ_HANDLED;
 }
@@ -2142,6 +2157,8 @@ static int hdmi_probe(struct platform_device *pdev)
 
         hdata->hpd = gpio_get_value(hdata->hpd_gpio);
 
+        INIT_DELAYED_WORK(&hdata->hotplug_work, hdmi_hotplug_work_func);
+
         ret = devm_request_threaded_irq(dev, hdata->irq, NULL,
                         hdmi_irq_thread, IRQF_TRIGGER_RISING |
                         IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
@@ -2167,6 +2184,8 @@ static int hdmi_remove(struct platform_device *pdev)
 {
         struct hdmi_context *hdata = hdmi_display.ctx;
 
+        cancel_delayed_work_sync(&hdata->hotplug_work);
+
         put_device(&hdata->hdmiphy_port->dev);
         put_device(&hdata->ddc_adpt->dev);