drm/mediatek: dp: Don't register HPD interrupt handler for eDP case

The interrupt handler for HPD is useful only if a display is actually
supposed to be hotpluggable, as that manages the machinery to perform
cable (un)plug detection, debouncing and setup for re-training.

Since eDP panels are not supposed to be hotpluggable we can avoid
using the HPD interrupts altogether and rely on HPD polling only
for the suspend/resume case, saving us some spinlocking action and
the overhead of interrupts firing at every suspend/resume cycle,
achieving a faster (even if just slightly) display resume.

Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Tested-by: Chen-Yu Tsai <wenst@chromium.org>
Reviewed-by: Alexandre Mergnat <amergnat@baylibre.com>
Reviewed-by: CK Hu <ck.hu@mediatek.com>
Link: https://patchwork.kernel.org/project/dri-devel/patch/20230725073234.55892-12-angelogioacchino.delregno@collabora.com/
Signed-off-by: Chun-Kuang Hu <chunkuang.hu@kernel.org>

diff --git a/drivers/gpu/drm/mediatek/mtk_dp.c b/drivers/gpu/drm/mediatek/mtk_dp.c
index ba750d4..c06fcc7 100644 (file)
--- a/drivers/gpu/drm/mediatek/mtk_dp.c
+++ b/drivers/gpu/drm/mediatek/mtk_dp.c
@@ -2182,9 +2182,11 @@ static int mtk_dp_bridge_attach(struct drm_bridge *bridge,
 
        mtk_dp->drm_dev = bridge->dev;
 
-       irq_clear_status_flags(mtk_dp->irq, IRQ_NOAUTOEN);
-       enable_irq(mtk_dp->irq);
-       mtk_dp_hwirq_enable(mtk_dp, true);
+       if (mtk_dp->bridge.type != DRM_MODE_CONNECTOR_eDP) {
+               irq_clear_status_flags(mtk_dp->irq, IRQ_NOAUTOEN);
+               enable_irq(mtk_dp->irq);
+               mtk_dp_hwirq_enable(mtk_dp, true);
+       }
 
        return 0;
 
@@ -2199,8 +2201,10 @@ static void mtk_dp_bridge_detach(struct drm_bridge *bridge)
 {
        struct mtk_dp *mtk_dp = mtk_dp_from_bridge(bridge);
 
-       mtk_dp_hwirq_enable(mtk_dp, false);
-       disable_irq(mtk_dp->irq);
+       if (mtk_dp->bridge.type != DRM_MODE_CONNECTOR_eDP) {
+               mtk_dp_hwirq_enable(mtk_dp, false);
+               disable_irq(mtk_dp->irq);
+       }
        mtk_dp->drm_dev = NULL;
        mtk_dp_poweroff(mtk_dp);
        drm_dp_aux_unregister(&mtk_dp->aux);
@@ -2579,32 +2583,44 @@ static int mtk_dp_probe(struct platform_device *pdev)
        mtk_dp->dev = dev;
        mtk_dp->data = (struct mtk_dp_data *)of_device_get_match_data(dev);
 
-       mtk_dp->irq = platform_get_irq(pdev, 0);
-       if (mtk_dp->irq < 0)
-               return dev_err_probe(dev, mtk_dp->irq,
-                                    "failed to request dp irq resource\n");
-
        ret = mtk_dp_dt_parse(mtk_dp, pdev);
        if (ret)
                return dev_err_probe(dev, ret, "Failed to parse dt\n");
 
+       /*
+        * Request the interrupt and install service routine only if we are
+        * on full DisplayPort.
+        * For eDP, polling the HPD instead is more convenient because we
+        * don't expect any (un)plug events during runtime, hence we can
+        * avoid some locking.
+        */
+       if (mtk_dp->data->bridge_type != DRM_MODE_CONNECTOR_eDP) {
+               mtk_dp->irq = platform_get_irq(pdev, 0);
+               if (mtk_dp->irq < 0)
+                       return dev_err_probe(dev, mtk_dp->irq,
+                                            "failed to request dp irq resource\n");
+
+               spin_lock_init(&mtk_dp->irq_thread_lock);
+
+               irq_set_status_flags(mtk_dp->irq, IRQ_NOAUTOEN);
+               ret = devm_request_threaded_irq(dev, mtk_dp->irq, mtk_dp_hpd_event,
+                                               mtk_dp_hpd_event_thread,
+                                               IRQ_TYPE_LEVEL_HIGH, dev_name(dev),
+                                               mtk_dp);
+               if (ret)
+                       return dev_err_probe(dev, ret,
+                                            "failed to request mediatek dptx irq\n");
+
+               mtk_dp->need_debounce = true;
+               timer_setup(&mtk_dp->debounce_timer, mtk_dp_debounce_timer, 0);
+       }
+
        mtk_dp->aux.name = "aux_mtk_dp";
        mtk_dp->aux.dev = dev;
        mtk_dp->aux.transfer = mtk_dp_aux_transfer;
        mtk_dp->aux.wait_hpd_asserted = mtk_dp_wait_hpd_asserted;
        drm_dp_aux_init(&mtk_dp->aux);
 
-       spin_lock_init(&mtk_dp->irq_thread_lock);
-
-       irq_set_status_flags(mtk_dp->irq, IRQ_NOAUTOEN);
-       ret = devm_request_threaded_irq(dev, mtk_dp->irq, mtk_dp_hpd_event,
-                                       mtk_dp_hpd_event_thread,
-                                       IRQ_TYPE_LEVEL_HIGH, dev_name(dev),
-                                       mtk_dp);
-       if (ret)
-               return dev_err_probe(dev, ret,
-                                    "failed to request mediatek dptx irq\n");
-
        platform_set_drvdata(pdev, mtk_dp);
 
        if (mtk_dp->data->audio_supported) {
@@ -2626,9 +2642,6 @@ static int mtk_dp_probe(struct platform_device *pdev)
        mtk_dp->bridge.of_node = dev->of_node;
        mtk_dp->bridge.type = mtk_dp->data->bridge_type;
 
-       mtk_dp->need_debounce = true;
-       timer_setup(&mtk_dp->debounce_timer, mtk_dp_debounce_timer, 0);
-
        if (mtk_dp->bridge.type == DRM_MODE_CONNECTOR_eDP) {
                /*
                 * Set the data lanes to idle in case the bootloader didn't
@@ -2639,6 +2652,9 @@ static int mtk_dp_probe(struct platform_device *pdev)
                mtk_dp_initialize_aux_settings(mtk_dp);
                mtk_dp_power_enable(mtk_dp);
 
+               /* Disable HW interrupts: we don't need any for eDP */
+               mtk_dp_hwirq_enable(mtk_dp, false);
+
                /*
                 * Power on the AUX to allow reading the EDID from aux-bus:
                 * please note that it is necessary to call power off in the
@@ -2684,7 +2700,8 @@ 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);
+       if (mtk_dp->data->bridge_type != DRM_MODE_CONNECTOR_eDP)
+               del_timer_sync(&mtk_dp->debounce_timer);
        platform_device_unregister(mtk_dp->phy_dev);
        if (mtk_dp->audio_pdev)
                platform_device_unregister(mtk_dp->audio_pdev);
@@ -2698,7 +2715,8 @@ static int mtk_dp_suspend(struct device *dev)
        struct mtk_dp *mtk_dp = dev_get_drvdata(dev);
 
        mtk_dp_power_disable(mtk_dp);
-       mtk_dp_hwirq_enable(mtk_dp, false);
+       if (mtk_dp->bridge.type != DRM_MODE_CONNECTOR_eDP)
+               mtk_dp_hwirq_enable(mtk_dp, false);
        pm_runtime_put_sync(dev);
 
        return 0;
@@ -2710,7 +2728,8 @@ static int mtk_dp_resume(struct device *dev)
 
        pm_runtime_get_sync(dev);
        mtk_dp_init_port(mtk_dp);
-       mtk_dp_hwirq_enable(mtk_dp, true);
+       if (mtk_dp->bridge.type != DRM_MODE_CONNECTOR_eDP)
+               mtk_dp_hwirq_enable(mtk_dp, true);
        mtk_dp_power_enable(mtk_dp);
 
        return 0;