[PATCH 1/3] dmaengine: tegra210-adma: Fix crash during probe

[Jon Hunter <jonathanh@nvidia.com>]

Commit f33e7bb3eb92 ("dmaengine: tegra210-adma: restore channel status")
added support to save and restore the DMA channel registers when runtime
suspending the ADMA. This change is causing the kernel to crash when
probing the ADMA, if the device is probed deferred when looking up the
channel interrupts. The crash occurs because not all of the channel base
addresses have been setup at this point and in the clean-up path of the
probe, pm_runtime_suspend() is called invoking its callback which
expects all the channel base addresses to be initialised.

Although this could be fixed by simply checking for a NULL address, on
further review of the driver it seems more appropriate that we only call
pm_runtime_get_sync() after all the channel interrupts and base
addresses have been configured. Therefore, fix this crash by moving the
calls to pm_runtime_enable(), pm_runtime_get_sync() and
tegra_adma_init() after the DMA channels have been initialised.

Fixes: f33e7bb3eb92 ("dmaengine: tegra210-adma: restore channel status")

Signed-off-by: Jon Hunter <jonathanh@nvidia.com>
---
 drivers/dma/tegra210-adma.c | 26 +++++++++++++-------------
 1 file changed, 13 insertions(+), 13 deletions(-)

diff --git a/drivers/dma/tegra210-adma.c b/drivers/dma/tegra210-adma.c
index 21f6be16d013..3ec3d71acd25 100644
--- a/drivers/dma/tegra210-adma.c
+++ b/drivers/dma/tegra210-adma.c
@@ -845,16 +845,6 @@ static int tegra_adma_probe(struct platform_device *pdev)
 		return PTR_ERR(tdma->ahub_clk);
 	}
 
-	pm_runtime_enable(&pdev->dev);
-
-	ret = pm_runtime_get_sync(&pdev->dev);
-	if (ret < 0)
-		goto rpm_disable;
-
-	ret = tegra_adma_init(tdma);
-	if (ret)
-		goto rpm_put;
-
 	INIT_LIST_HEAD(&tdma->dma_dev.channels);
 	for (i = 0; i < tdma->nr_channels; i++) {
 		struct tegra_adma_chan *tdc = &tdma->channels[i];
@@ -873,6 +863,16 @@ static int tegra_adma_probe(struct platform_device *pdev)
 		tdc->tdma = tdma;
 	}
 
+	pm_runtime_enable(&pdev->dev);
+
+	ret = pm_runtime_get_sync(&pdev->dev);
+	if (ret < 0)
+		goto rpm_disable;
+
+	ret = tegra_adma_init(tdma);
+	if (ret)
+		goto rpm_put;
+
 	dma_cap_set(DMA_SLAVE, tdma->dma_dev.cap_mask);
 	dma_cap_set(DMA_PRIVATE, tdma->dma_dev.cap_mask);
 	dma_cap_set(DMA_CYCLIC, tdma->dma_dev.cap_mask);
@@ -916,13 +916,13 @@ static int tegra_adma_probe(struct platform_device *pdev)
 
 dma_remove:
 	dma_async_device_unregister(&tdma->dma_dev);
-irq_dispose:
-	while (--i >= 0)
-		irq_dispose_mapping(tdma->channels[i].irq);
 rpm_put:
 	pm_runtime_put_sync(&pdev->dev);
 rpm_disable:
 	pm_runtime_disable(&pdev->dev);
+irq_dispose:
+	while (--i >= 0)
+		irq_dispose_mapping(tdma->channels[i].irq);
 
 	return ret;
 }
-- 
2.7.4