drm/tegra: dp - Implement hotplug detection in work queue

Calling the drm_helper_hpd_irq_event() helper can sleep, so instead of
invoking it directly from the interrupt handler, schedule a work queue
and run it from there.

Signed-off-by: Thierry Reding <treding@nvidia.com>

diff --git a/drivers/gpu/drm/tegra/dpaux.c b/drivers/gpu/drm/tegra/dpaux.c
index 2b725ba..208fc1b 100644 (file)
--- a/drivers/gpu/drm/tegra/dpaux.c
+++ b/drivers/gpu/drm/tegra/dpaux.c
@@ -15,6 +15,7 @@
 #include <linux/platform_device.h>
 #include <linux/reset.h>
 #include <linux/regulator/consumer.h>
+#include <linux/workqueue.h>
 
 #include <drm/drm_dp_helper.h>
 #include <drm/drm_panel.h>
@@ -41,6 +42,7 @@ struct tegra_dpaux {
        struct regulator *vdd;
 
        struct completion complete;
+       struct work_struct work;
        struct list_head list;
 };
 
@@ -49,6 +51,11 @@ static inline struct tegra_dpaux *to_dpaux(struct drm_dp_aux *aux)
        return container_of(aux, struct tegra_dpaux, aux);
 }
 
+static inline struct tegra_dpaux *work_to_dpaux(struct work_struct *work)
+{
+       return container_of(work, struct tegra_dpaux, work);
+}
+
 static inline unsigned long tegra_dpaux_readl(struct tegra_dpaux *dpaux,
                                              unsigned long offset)
 {
@@ -231,6 +238,14 @@ static ssize_t tegra_dpaux_transfer(struct drm_dp_aux *aux,
        return ret;
 }
 
+static void tegra_dpaux_hotplug(struct work_struct *work)
+{
+       struct tegra_dpaux *dpaux = work_to_dpaux(work);
+
+       if (dpaux->output)
+               drm_helper_hpd_irq_event(dpaux->output->connector.dev);
+}
+
 static irqreturn_t tegra_dpaux_irq(int irq, void *data)
 {
        struct tegra_dpaux *dpaux = data;
@@ -241,16 +256,8 @@ static irqreturn_t tegra_dpaux_irq(int irq, void *data)
        value = tegra_dpaux_readl(dpaux, DPAUX_INTR_AUX);
        tegra_dpaux_writel(dpaux, value, DPAUX_INTR_AUX);
 
-       if (value & DPAUX_INTR_PLUG_EVENT) {
-               if (dpaux->output) {
-                       drm_helper_hpd_irq_event(dpaux->output->connector.dev);
-               }
-       }
-
-       if (value & DPAUX_INTR_UNPLUG_EVENT) {
-               if (dpaux->output)
-                       drm_helper_hpd_irq_event(dpaux->output->connector.dev);
-       }
+       if (value & (DPAUX_INTR_PLUG_EVENT | DPAUX_INTR_UNPLUG_EVENT))
+               schedule_work(&dpaux->work);
 
        if (value & DPAUX_INTR_IRQ_EVENT) {
                /* TODO: handle this */
@@ -273,6 +280,7 @@ static int tegra_dpaux_probe(struct platform_device *pdev)
        if (!dpaux)
                return -ENOMEM;
 
+       INIT_WORK(&dpaux->work, tegra_dpaux_hotplug);
        init_completion(&dpaux->complete);
        INIT_LIST_HEAD(&dpaux->list);
        dpaux->dev = &pdev->dev;
@@ -361,6 +369,8 @@ static int tegra_dpaux_remove(struct platform_device *pdev)
        list_del(&dpaux->list);
        mutex_unlock(&dpaux_lock);
 
+       cancel_work_sync(&dpaux->work);
+
        clk_disable_unprepare(dpaux->clk_parent);
        reset_control_assert(dpaux->rst);
        clk_disable_unprepare(dpaux->clk);