Add runtime PM stubs to the Synopsys DesignWare DisplayPort bridge
driver. Support is not enabled automatically and must be hooked up
in the vendor specific glue code.

Signed-off-by: Sebastian Reichel <[email protected]>
---
 drivers/gpu/drm/bridge/synopsys/dw-dp.c | 107 +++++++++++++++++++++++++++++---
 include/drm/bridge/dw_dp.h              |   3 +
 2 files changed, 102 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/bridge/synopsys/dw-dp.c 
b/drivers/gpu/drm/bridge/synopsys/dw-dp.c
index 2042bc00f906..1bbb39b8d0be 100644
--- a/drivers/gpu/drm/bridge/synopsys/dw-dp.c
+++ b/drivers/gpu/drm/bridge/synopsys/dw-dp.c
@@ -328,6 +328,7 @@ struct dw_dp {
        struct dw_dp_link link;
        struct dw_dp_plat_data plat_data;
        u8 pixel_mode;
+       bool usbc_mode;
 
        struct drm_bridge *next_bridge;
 
@@ -1467,6 +1468,11 @@ static ssize_t dw_dp_aux_transfer(struct drm_dp_aux *aux,
        if (WARN_ON(msg->size > 16))
                return -E2BIG;
 
+       PM_RUNTIME_ACQUIRE_AUTOSUSPEND(dp->dev, pm);
+       ret = PM_RUNTIME_ACQUIRE_ERR(&pm);
+       if (ret)
+               return ret;
+
        reinit_completion(&dp->complete);
 
        switch (msg->request & ~DP_AUX_I2C_MOT) {
@@ -1659,6 +1665,12 @@ static void dw_dp_bridge_atomic_enable(struct drm_bridge 
*bridge,
        struct drm_connector_state *conn_state;
        int ret;
 
+       ret = pm_runtime_get_active(dp->dev, RPM_TRANSPARENT);
+       if (ret) {
+               dev_err(dp->dev, "runtime PM failure\n");
+               return;
+       }
+
        connector = drm_atomic_get_new_connector_for_encoder(state, 
bridge->encoder);
        if (!connector) {
                dev_err(dp->dev, "failed to get connector\n");
@@ -1713,6 +1725,7 @@ static void dw_dp_bridge_atomic_disable(struct drm_bridge 
*bridge,
        dw_dp_link_disable(dp);
        bitmap_zero(dp->sdp_reg_bank, SDP_REG_BANK_SIZE);
        dw_dp_reset(dp);
+       pm_runtime_put_autosuspend(dp->dev);
 }
 
 static bool dw_dp_hpd_detect_link(struct dw_dp *dp, struct drm_connector 
*connector)
@@ -1733,6 +1746,10 @@ static enum drm_connector_status 
dw_dp_bridge_detect(struct drm_bridge *bridge,
 {
        struct dw_dp *dp = bridge_to_dp(bridge);
 
+       PM_RUNTIME_ACQUIRE_AUTOSUSPEND(dp->dev, pm);
+       if (PM_RUNTIME_ACQUIRE_ERR(&pm))
+               return connector_status_disconnected;
+
        if (!dw_dp_hpd_detect(dp))
                return connector_status_disconnected;
 
@@ -1915,6 +1932,11 @@ static void dw_dp_hpd_work(struct work_struct *work)
        bool long_hpd;
        int ret;
 
+       PM_RUNTIME_ACQUIRE_AUTOSUSPEND(dp->dev, pm);
+       ret = PM_RUNTIME_ACQUIRE_ERR(&pm);
+       if (ret)
+               return;
+
        mutex_lock(&dp->irq_lock);
        long_hpd = dp->hotplug.long_hpd;
        mutex_unlock(&dp->irq_lock);
@@ -1966,6 +1988,9 @@ static irqreturn_t dw_dp_irq(int irq, void *data)
        struct dw_dp *dp = data;
        u32 value;
 
+       /* interrupt can only trigger for running device */
+       guard(pm_runtime_noresume)(dp->dev);
+
        regmap_read(dp->regmap, DW_DP_GENERAL_INTERRUPT, &value);
        if (!value)
                return IRQ_NONE;
@@ -2064,25 +2089,51 @@ int dw_dp_bind(struct dw_dp *dp, struct drm_encoder 
*encoder)
                goto put_next_bridge;
        }
 
-       if (dw_dp_is_routed_to_usb_c(encoder)) {
-               dev_dbg(dev, "USB-C mode\n");
+       dp->usbc_mode = dw_dp_is_routed_to_usb_c(encoder);
 
-               if (dp->plat_data.hpd_sw_sel)
-                       dp->plat_data.hpd_sw_sel(dp->plat_data.data, 1);
+       ret = pm_runtime_get_active(dev, RPM_TRANSPARENT);
+       if (ret) {
+               dev_err_probe(dev, ret, "Failed to get runtime PM\n");
+               goto put_next_bridge;
        }
 
-       dw_dp_init_hw(dp);
+       /* resume once if runtime PM is disabled */
+       if (!pm_runtime_enabled(dev)) {
+               ret = dw_dp_runtime_resume(dp);
+               if (ret)
+                       goto put_runtime_pm;
+       }
+
+       if (dp->plat_data.hpd_sw_sel)
+               dp->plat_data.hpd_sw_sel(dp->plat_data.data, dp->usbc_mode);
 
        ret = phy_init(dp->phy);
        if (ret) {
                dev_err_probe(dev, ret, "phy init failed\n");
-               goto put_next_bridge;
+               goto put_manual_pm;
        }
 
        enable_irq(dp->irq);
 
+       /*
+        * USB-C has out-of-band hotplug detection, so device may enter
+        * runtime suspend. Native mode needs to be resumed for working
+        * hotplug detection.
+        */
+       if (dp->usbc_mode) {
+               dev_dbg(dev, "USB-C mode\n");
+               pm_runtime_put_autosuspend(dp->dev);
+       }
+
        return 0;
 
+put_manual_pm:
+       if (!pm_runtime_enabled(dev))
+               dw_dp_runtime_suspend(dp);
+
+put_runtime_pm:
+       pm_runtime_put_sync(dp->dev);
+
 put_next_bridge:
        drm_bridge_put(dp->next_bridge);
 
@@ -2101,6 +2152,11 @@ void dw_dp_unbind(struct dw_dp *dp)
        disable_irq(dp->irq);
        cancel_work_sync(&dp->hpd_work);
        phy_exit(dp->phy);
+       if (!dp->usbc_mode)
+               pm_runtime_put_sync(dp->dev);
+       /* suspend once if runtime PM is disabled */
+       if (!pm_runtime_enabled(dp->dev))
+               dw_dp_runtime_suspend(dp);
        drm_bridge_put(dp->next_bridge);
        drm_dp_aux_unregister(&dp->aux);
        drm_bridge_remove(&dp->bridge);
@@ -2149,13 +2205,13 @@ struct dw_dp *dw_dp_probe(struct platform_device *pdev, 
const struct dw_dp_plat_
                return ERR_CAST(dp->phy);
        }
 
-       dp->apb_clk = devm_clk_get_enabled(dev, "apb");
+       dp->apb_clk = devm_clk_get(dev, "apb");
        if (IS_ERR(dp->apb_clk)) {
                dev_err_probe(dev, PTR_ERR(dp->apb_clk), "failed to get apb 
clock\n");
                return ERR_CAST(dp->apb_clk);
        }
 
-       dp->aux_clk = devm_clk_get_enabled(dev, "aux");
+       dp->aux_clk = devm_clk_get(dev, "aux");
        if (IS_ERR(dp->aux_clk)) {
                dev_err_probe(dev, PTR_ERR(dp->aux_clk), "failed to get aux 
clock\n");
                return ERR_CAST(dp->aux_clk);
@@ -2200,6 +2256,41 @@ struct dw_dp *dw_dp_probe(struct platform_device *pdev, 
const struct dw_dp_plat_
 }
 EXPORT_SYMBOL_GPL(dw_dp_probe);
 
+int dw_dp_runtime_suspend(struct dw_dp *dp)
+{
+       clk_disable_unprepare(dp->aux_clk);
+       clk_disable_unprepare(dp->apb_clk);
+
+       return 0;
+}
+EXPORT_SYMBOL_GPL(dw_dp_runtime_suspend);
+
+int dw_dp_runtime_resume(struct dw_dp *dp)
+{
+       int ret;
+
+       ret = clk_prepare_enable(dp->apb_clk);
+       if (ret)
+               return ret;
+
+       ret = clk_prepare_enable(dp->aux_clk);
+       if (ret) {
+               clk_disable_unprepare(dp->apb_clk);
+               return ret;
+       }
+
+       dw_dp_init_hw(dp);
+
+       /*
+        * HPD_HOT_PLUG bit is asserted only after the sink holds HPD
+        * high for at least 100ms.
+        */
+       msleep(110);
+
+       return 0;
+}
+EXPORT_SYMBOL_GPL(dw_dp_runtime_resume);
+
 MODULE_AUTHOR("Andy Yan <[email protected]>");
 MODULE_DESCRIPTION("DW DP Core Library");
 MODULE_LICENSE("GPL");
diff --git a/include/drm/bridge/dw_dp.h b/include/drm/bridge/dw_dp.h
index 79b2cdf0df99..f20d2c2c40ca 100644
--- a/include/drm/bridge/dw_dp.h
+++ b/include/drm/bridge/dw_dp.h
@@ -29,4 +29,7 @@ int dw_dp_bind(struct dw_dp *dp, struct drm_encoder *encoder);
 void dw_dp_unbind(struct dw_dp *dp);
 
 struct dw_dp *dw_dp_probe(struct platform_device *pdev, const struct 
dw_dp_plat_data *plat_data);
+
+int dw_dp_runtime_suspend(struct dw_dp *dp);
+int dw_dp_runtime_resume(struct dw_dp *dp);
 #endif /* __DW_DP__ */

-- 
2.53.0

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