net: ethernet: ti: cpsw: fix bad register access in probe error path

commit c46ab7e0 upstream.

Make sure to keep the platform device runtime-resumed throughout probe
to avoid accessing the CPSW registers in the error path (e.g. for
deferred probe) with clocks disabled:

Unhandled fault: external abort on non-linefetch (0x1008) at 0xd0872d08
...
[<c04fabcc>] (cpsw_ale_control_set) from [<c04fb8b4>] (cpsw_ale_destroy+0x2c/0x44)
[<c04fb8b4>] (cpsw_ale_destroy) from [<c04fea58>] (cpsw_probe+0xbd0/0x10c4)
[<c04fea58>] (cpsw_probe) from [<c047b2a0>] (platform_drv_probe+0x5c/0xc0)

Fixes: df828598 ("netdev: driver: ethernet: Add TI CPSW driver")
Signed-off-by: Johan Hovold <johan@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
[bwh: Backported to 3.16:
 - s/cpsw->/priv->/g
 - Adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

drivers/net/ethernet/ti/cpsw.c

@@ -2140,13 +2140,12 @@ static int cpsw_probe(struct platform_device *pdev)
 	 */
 	pm_runtime_get_sync(&pdev->dev);
 	priv->version = readl(&priv->regs->id_ver);
-	pm_runtime_put_sync(&pdev->dev);
 
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
 	priv->wr_regs = devm_ioremap_resource(&pdev->dev, res);
 	if (IS_ERR(priv->wr_regs)) {
 		ret = PTR_ERR(priv->wr_regs);
-		goto clean_runtime_disable_ret;
+		goto clean_pm_runtime_put_ret;
 	}
 
 	memset(&dma_params, 0, sizeof(dma_params));
@@ -2183,7 +2182,7 @@ static int cpsw_probe(struct platform_device *pdev)
 	default:
 		dev_err(priv->dev, "unknown version 0x%08x\n", priv->version);
 		ret = -ENODEV;
-		goto clean_runtime_disable_ret;
+		goto clean_pm_runtime_put_ret;
 	}
 	for (i = 0; i < priv->data.slaves; i++) {
 		struct cpsw_slave *slave = &priv->slaves[i];
@@ -2211,7 +2210,7 @@ static int cpsw_probe(struct platform_device *pdev)
 	if (!priv->dma) {
 		dev_err(priv->dev, "error initializing dma\n");
 		ret = -ENOMEM;
-		goto clean_runtime_disable_ret;
+		goto clean_pm_runtime_put_ret;
 	}
 
 	priv->txch = cpdma_chan_create(priv->dma, tx_chan_num(0),
@@ -2283,6 +2282,8 @@ static int cpsw_probe(struct platform_device *pdev)
 		}
 	}
 
+	pm_runtime_put(&pdev->dev);
+
 	return 0;
 
 clean_ale_ret:
@@ -2291,6 +2292,8 @@ static int cpsw_probe(struct platform_device *pdev)
 	cpdma_chan_destroy(priv->txch);
 	cpdma_chan_destroy(priv->rxch);
 	cpdma_ctlr_destroy(priv->dma);
+clean_pm_runtime_put_ret:
+	pm_runtime_put_sync(&pdev->dev);
 clean_runtime_disable_ret:
 	pm_runtime_disable(&pdev->dev);
 clean_ndev_ret: