dmaengine: tegra-apb: Correct runtime-pm usage

The tegra-apb DMA driver enables runtime-pm but never calls
pm_runtime_get/put and hence the runtime-pm callbacks are never invoked.
The driver manages the clocks by directly calling clk_prepare_enable()
and clk_unprepare_disable().

Fix this by replacing the clk_prepare_enable() and clk_disable_unprepare()
with pm_runtime_get_sync() and pm_runtime_put(), respectively. Note that
the consequence of this is that if runtime-pm is disabled, then the clocks
will remain on the entire time the driver is loaded. However, if
runtime-pm is disabled, then power is not most likely not a concern.

Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>

1 files changed, 18 insertions, 25 deletions

diff --git a/drivers/dma/tegra20-apb-dma.c b/drivers/dma/tegra20-apb-dma.c
index c8f79dcaaee8..f68bccf55a24 100644
--- a/drivers/dma/tegra20-apb-dma.c
+++ b/drivers/dma/tegra20-apb-dma.c
@@ -1186,10 +1186,12 @@ static int tegra_dma_alloc_chan_resources(struct dma_chan *dc)
 
         dma_cookie_init(&tdc->dma_chan);
         tdc->config_init = false;
-        ret = clk_prepare_enable(tdma->dma_clk);
+
+        ret = pm_runtime_get_sync(tdma->dev);
         if (ret < 0)
-                dev_err(tdc2dev(tdc), "clk_prepare_enable failed: %d\n", ret);
-        return ret;
+                return ret;
+
+        return 0;
 }
 
 static void tegra_dma_free_chan_resources(struct dma_chan *dc)
@@ -1232,7 +1234,7 @@ static void tegra_dma_free_chan_resources(struct dma_chan *dc)
                 list_del(&sg_req->node);
                 kfree(sg_req);
         }
-        clk_disable_unprepare(tdma->dma_clk);
+        pm_runtime_put(tdma->dev);
 
         tdc->slave_id = 0;
 }
@@ -1356,20 +1358,14 @@ static int tegra_dma_probe(struct platform_device *pdev)
         spin_lock_init(&tdma->global_lock);
 
         pm_runtime_enable(&pdev->dev);
-        if (!pm_runtime_enabled(&pdev->dev)) {
+        if (!pm_runtime_enabled(&pdev->dev))
                 ret = tegra_dma_runtime_resume(&pdev->dev);
-                if (ret) {
-                        dev_err(&pdev->dev, "dma_runtime_resume failed %d\n",
-                                ret);
-                        goto err_pm_disable;
-                }
-        }
+        else
+                ret = pm_runtime_get_sync(&pdev->dev);
 
-        /* Enable clock before accessing registers */
-        ret = clk_prepare_enable(tdma->dma_clk);
         if (ret < 0) {
-                dev_err(&pdev->dev, "clk_prepare_enable failed: %d\n", ret);
-                goto err_pm_disable;
+                pm_runtime_disable(&pdev->dev);
+                return ret;
         }
 
         /* Reset DMA controller */
@@ -1382,7 +1378,7 @@ static int tegra_dma_probe(struct platform_device *pdev)
         tdma_write(tdma, TEGRA_APBDMA_CONTROL, 0);
         tdma_write(tdma, TEGRA_APBDMA_IRQ_MASK_SET, 0xFFFFFFFFul);
 
-        clk_disable_unprepare(tdma->dma_clk);
+        pm_runtime_put(&pdev->dev);
 
         INIT_LIST_HEAD(&tdma->dma_dev.channels);
         for (i = 0; i < cdata->nr_channels; i++) {
@@ -1485,7 +1481,6 @@ err_irq:
                 tasklet_kill(&tdc->tasklet);
         }
 
-err_pm_disable:
         pm_runtime_disable(&pdev->dev);
         if (!pm_runtime_status_suspended(&pdev->dev))
                 tegra_dma_runtime_suspend(&pdev->dev);
@@ -1543,7 +1538,7 @@ static int tegra_dma_pm_suspend(struct device *dev)
         int ret;
 
         /* Enable clock before accessing register */
-        ret = tegra_dma_runtime_resume(dev);
+        ret = pm_runtime_get_sync(dev);
         if (ret < 0)
                 return ret;
 
@@ -1560,7 +1555,7 @@ static int tegra_dma_pm_suspend(struct device *dev)
         }
 
         /* Disable clock */
-        tegra_dma_runtime_suspend(dev);
+        pm_runtime_put(dev);
         return 0;
 }
 
@@ -1571,7 +1566,7 @@ static int tegra_dma_pm_resume(struct device *dev)
         int ret;
 
         /* Enable clock before accessing register */
-        ret = tegra_dma_runtime_resume(dev);
+        ret = pm_runtime_get_sync(dev);
         if (ret < 0)
                 return ret;
 
@@ -1592,16 +1587,14 @@ static int tegra_dma_pm_resume(struct device *dev)
         }
 
         /* Disable clock */
-        tegra_dma_runtime_suspend(dev);
+        pm_runtime_put(dev);
         return 0;
 }
 #endif
 
 static const struct dev_pm_ops tegra_dma_dev_pm_ops = {
-#ifdef CONFIG_PM
-        .runtime_suspend = tegra_dma_runtime_suspend,
-        .runtime_resume = tegra_dma_runtime_resume,
-#endif
+        SET_RUNTIME_PM_OPS(tegra_dma_runtime_suspend, tegra_dma_runtime_resume,
+                           NULL)
         SET_SYSTEM_SLEEP_PM_OPS(tegra_dma_pm_suspend, tegra_dma_pm_resume)
 };