Re: [PATCH] net: fec: fix enet_out clock handling

From: Michael Heimpold
Date: Fri Nov 27 2015 - 10:23:54 EST


Hi,

Am 27.11.2015 um 14:39 schrieb Lothar WaÃmann:
When ENET_OUT is being used as reference clock for an external PHY,
the clock must not be disabled while the PHY is active. Otherwise the
PHY may lose its internal state and require a reset to become
functional again.

A symptom for this bug is a network interface that constantly toggles
between UP and DOWN state:
fec 800f0000.ethernet eth0: Link is Up - 100Mbps/Full - flow control rx/tx
fec 800f0000.ethernet eth0: Link is Down
fec 800f0000.ethernet eth0: Link is Up - 100Mbps/Full - flow control rx/tx
fec 800f0000.ethernet eth0: Link is Down
[...]

I would add a sentence about the solution, e.g. moving ENET_OUT handling to driver probe etc.

Signed-off-by: Lothar WaÃmann <LW@xxxxxxxxxxxxxxxxxxx>
---
drivers/net/ethernet/freescale/fec_main.c | 34 +++++++++++++------------------
1 file changed, 14 insertions(+), 20 deletions(-)

diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c
index d2328fc..d9df4c5 100644
--- a/drivers/net/ethernet/freescale/fec_main.c
+++ b/drivers/net/ethernet/freescale/fec_main.c
@@ -1857,11 +1857,6 @@ static int fec_enet_clk_enable(struct net_device *ndev, bool enable)
ret = clk_prepare_enable(fep->clk_ahb);
if (ret)
return ret;
- if (fep->clk_enet_out) {
- ret = clk_prepare_enable(fep->clk_enet_out);
- if (ret)
- goto failed_clk_enet_out;
- }
if (fep->clk_ptp) {
mutex_lock(&fep->ptp_clk_mutex);
ret = clk_prepare_enable(fep->clk_ptp);
@@ -1873,35 +1868,26 @@ static int fec_enet_clk_enable(struct net_device *ndev, bool enable)
}
mutex_unlock(&fep->ptp_clk_mutex);
}
- if (fep->clk_ref) {
- ret = clk_prepare_enable(fep->clk_ref);
- if (ret)
- goto failed_clk_ref;
- }
+ ret = clk_prepare_enable(fep->clk_ref);
+ if (ret)
+ goto failed_clk_ref;

This change seems unrelated to the problem. At least, I can leave this part out
and the toggle still disappear after apply the remaining parts.
However, I've only my Duckbill (iMX28) around to test with.

} else {
clk_disable_unprepare(fep->clk_ahb);
- if (fep->clk_enet_out)
- clk_disable_unprepare(fep->clk_enet_out);
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);
}
- if (fep->clk_ref)
- clk_disable_unprepare(fep->clk_ref);
+ clk_disable_unprepare(fep->clk_ref);

Same as above, might be unrelated.

}
return 0;
failed_clk_ref:
- if (fep->clk_ref)
- clk_disable_unprepare(fep->clk_ref);
+ clk_disable_unprepare(fep->clk_ref);
dito

failed_clk_ptp:
- if (fep->clk_enet_out)
- clk_disable_unprepare(fep->clk_enet_out);
-failed_clk_enet_out:
- clk_disable_unprepare(fep->clk_ahb);
+ clk_disable_unprepare(fep->clk_ahb);
return ret;
}
@@ -3425,6 +3411,10 @@ fec_probe(struct platform_device *pdev)
if (ret)
goto failed_clk;
+ ret = clk_prepare_enable(fep->clk_enet_out);
+ if (ret)
+ goto failed_clk_enet_out;
+
As enet_out is optional, shouldn't this block be guarded by
if (fep->clk_enet_out)... ?

ret = clk_prepare_enable(fep->clk_ipg);
if (ret)
goto failed_clk_ipg;
@@ -3509,6 +3499,8 @@ failed_init:
if (fep->reg_phy)
regulator_disable(fep->reg_phy);
failed_regulator:
+ clk_disable_unprepare(fep->clk_enet_out);
here too?
+failed_clk_enet_out:
clk_disable_unprepare(fep->clk_ipg);
failed_clk_ipg:
fec_enet_clk_enable(ndev, false);
@@ -3531,6 +3523,8 @@ fec_drv_remove(struct platform_device *pdev)
fec_ptp_stop(pdev);
unregister_netdev(ndev);
fec_enet_mii_remove(fep);
+ fec_enet_clk_enable(ndev, false);
+ clk_disable_unprepare(fep->clk_enet_out);

and here too?

if (fep->reg_phy)
regulator_disable(fep->reg_phy);
of_node_put(fep->phy_node);

Mit freundlichen GrÃÃen / Kind regards
Michael Heimpold
--
Software Engineer

I2SE GmbH Tel: +49 (0) 341 355667-00
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