net: fec: Fix division by zero

commit 7f7d6c282 (net: fec: Ensure that initialization is done prior to
request_irq()) placed fec_ptp_init() into a point that ptp clock was not
available, which causes a division by zero in fec_ptp_start_cyclecounter():

[   17.895723] Division by zero in kernel.
[   17.899571] Backtrace:
[   17.902094] [<80012564>] (dump_backtrace+0x0/0x10c) from [<8056deec>]
(dump_stack+0x18/0x1c)
[   17.910539]  r6:bfba8500 r5:8075c950 r4:bfba8000 r3:bfbd0000
[   17.916284] [<8056ded4>] (dump_stack+0x0/0x1c) from [<80012688>]
(__div0+0x18/0x20)
[   17.923968] [<80012670>] (__div0+0x0/0x20) from [<802829c4>] (Ldiv0+0x8/0x10)
[   17.931140] [<80398534>] (fec_ptp_start_cyclecounter+0x0/0x110) from
[<80394f64>] (fec_restart+0x6c8/0x754)
[   17.940898] [<8039489c>] (fec_restart+0x0/0x754) from [<803969a0>]
(fec_enet_adjust_link+0xdc/0x108)
[   17.950046] [<803968c4>] (fec_enet_adjust_link+0x0/0x108) from [<80390bc4>]
(phy_state_machine+0x178/0x534)
...

Fix this by rearraging the code so that fec_ptp_init() is called only after
the clocks have been properly acquired.

Tested on both mx53 and mx6 platforms.

Reported-by: Jim Baxter <jim_baxter@mentor.com>
Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 34 insertions, 34 deletions

diff --git a/drivers/net/ethernet/freescale/fec.c b/drivers/net/ethernet/freescale/fec.c
index 2dbb36c985c7..fccc3bf2141d 100644
--- a/drivers/net/ethernet/freescale/fec.c
+++ b/drivers/net/ethernet/freescale/fec.c
@@ -1782,33 +1782,6 @@ fec_probe(struct platform_device *pdev)
                 fep->phy_interface = ret;
         }
 
-        fep->bufdesc_ex =
-                pdev->id_entry->driver_data & FEC_QUIRK_HAS_BUFDESC_EX;
-        if (fep->bufdesc_ex)
-                fec_ptp_init(ndev, pdev);
-
-        ret = fec_enet_init(ndev);
-        if (ret)
-                goto failed_init;
-
-        for (i = 0; i < FEC_IRQ_NUM; i++) {
-                irq = platform_get_irq(pdev, i);
-                if (irq < 0) {
-                        if (i)
-                                break;
-                        ret = irq;
-                        goto failed_irq;
-                }
-                ret = request_irq(irq, fec_enet_interrupt, IRQF_DISABLED, pdev->name, ndev);
-                if (ret) {
-                        while (--i >= 0) {
-                                irq = platform_get_irq(pdev, i);
-                                free_irq(irq, ndev);
-                        }
-                        goto failed_irq;
-                }
-        }
-
         pinctrl = devm_pinctrl_get_select_default(&pdev->dev);
         if (IS_ERR(pinctrl)) {
                 ret = PTR_ERR(pinctrl);
@@ -1828,6 +1801,8 @@ fec_probe(struct platform_device *pdev)
         }
 
         fep->clk_ptp = devm_clk_get(&pdev->dev, "ptp");
+        fep->bufdesc_ex =
+                pdev->id_entry->driver_data & FEC_QUIRK_HAS_BUFDESC_EX;
         if (IS_ERR(fep->clk_ptp)) {
                 ret = PTR_ERR(fep->clk_ptp);
                 fep->bufdesc_ex = 0;
@@ -1850,6 +1825,31 @@ fec_probe(struct platform_device *pdev)
 
         fec_reset_phy(pdev);
 
+        if (fep->bufdesc_ex)
+                fec_ptp_init(ndev, pdev);
+
+        ret = fec_enet_init(ndev);
+        if (ret)
+                goto failed_init;
+
+        for (i = 0; i < FEC_IRQ_NUM; i++) {
+                irq = platform_get_irq(pdev, i);
+                if (irq < 0) {
+                        if (i)
+                                break;
+                        ret = irq;
+                        goto failed_irq;
+                }
+                ret = request_irq(irq, fec_enet_interrupt, IRQF_DISABLED, pdev->name, ndev);
+                if (ret) {
+                        while (--i >= 0) {
+                                irq = platform_get_irq(pdev, i);
+                                free_irq(irq, ndev);
+                        }
+                        goto failed_irq;
+                }
+        }
+
         ret = fec_enet_mii_init(pdev);
         if (ret)
                 goto failed_mii_init;
@@ -1866,6 +1866,13 @@ fec_probe(struct platform_device *pdev)
 failed_register:
         fec_enet_mii_remove(fep);
 failed_mii_init:
+failed_init:
+        for (i = 0; i < FEC_IRQ_NUM; i++) {
+                irq = platform_get_irq(pdev, i);
+                if (irq > 0)
+                        free_irq(irq, ndev);
+        }
+failed_irq:
 failed_regulator:
         clk_disable_unprepare(fep->clk_ahb);
         clk_disable_unprepare(fep->clk_ipg);
@@ -1873,14 +1880,7 @@ failed_regulator:
                 clk_disable_unprepare(fep->clk_ptp);
 failed_pin:
 failed_clk:
-        for (i = 0; i < FEC_IRQ_NUM; i++) {
-                irq = platform_get_irq(pdev, i);
-                if (irq > 0)
-                        free_irq(irq, ndev);
-        }
-failed_irq:
         iounmap(fep->hwp);
-failed_init:
 failed_ioremap:
         free_netdev(ndev);
 failed_alloc_etherdev: