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net: fec: ptp: avoid register access when ipg clock is disabled

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The current kernel hang on i.MX6SX with rootfs mount from MMC.
The root cause is that ptp uses a periodic timer to access enet register
even if ipg clock is disabled.

FEC ptp driver start one period timer to read 1588 counter register in the
ptp init function that is called after FEC driver is probed.

To save power, after FEC probe finish, FEC driver disable all clocks including
ipg clock that is needed for register access.

i.MX5x, i.MX6q/dl/sl FEC register access don't cause system hang when ipg clock
is disabled, just return zero value. But for i.MX6sx SOC, it cause system hang.

To avoid the issue, we need to check ptp clock status before ptp timer count access.

Signed-off-by: Fugang Duan <B38611@freescale.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Nimrod Andy
2014-08-21 17:09:38 +08:00
committed by David S. Miller
parent 08f1a1b9d1
commit 91c0d987a9
3 changed files with 41 additions and 15 deletions
Download Patch File Download Diff File Expand all files Collapse all files

18
drivers/net/ethernet/freescale/fec_main.c
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@@ -1611,17 +1611,27 @@ static int fec_enet_clk_enable(struct net_device *ndev, bool enable)
goto failed_clk_enet_out;
}
if (fep->clk_ptp) {
mutex_lock(&fep->ptp_clk_mutex);
ret = clk_prepare_enable(fep->clk_ptp);
if (ret)
if (ret) {
mutex_unlock(&fep->ptp_clk_mutex);
goto failed_clk_ptp;
} else {
fep->ptp_clk_on = true;
}
mutex_unlock(&fep->ptp_clk_mutex);
}
} else {
clk_disable_unprepare(fep->clk_ahb);
clk_disable_unprepare(fep->clk_ipg);
if (fep->clk_enet_out)
clk_disable_unprepare(fep->clk_enet_out);
if (fep->clk_ptp)
if (fep->clk_ptp) {
mutex_lock(&fep->ptp_clk_mutex);
clk_disable_unprepare(fep->clk_ptp);
fep->ptp_clk_on = false;
mutex_unlock(&fep->ptp_clk_mutex);
}
}
return 0;
@@ -2625,6 +2635,8 @@ fec_probe(struct platform_device *pdev)
if (IS_ERR(fep->clk_enet_out))
fep->clk_enet_out = NULL;
fep->ptp_clk_on = false;
mutex_init(&fep->ptp_clk_mutex);
fep->clk_ptp = devm_clk_get(&pdev->dev, "ptp");
fep->bufdesc_ex =
pdev->id_entry->driver_data & FEC_QUIRK_HAS_BUFDESC_EX;
@@ -2715,10 +2727,10 @@ fec_drv_remove(struct platform_device *pdev)
struct net_device *ndev = platform_get_drvdata(pdev);
struct fec_enet_private *fep = netdev_priv(ndev);
cancel_delayed_work_sync(&fep->time_keep);
cancel_work_sync(&fep->tx_timeout_work);
unregister_netdev(ndev);
fec_enet_mii_remove(fep);
del_timer_sync(&fep->time_keep);
if (fep->reg_phy)
regulator_disable(fep->reg_phy);
if (fep->ptp_clock)