[PATCH] net: phy: fix auto-negotiation stall due to unavailable interrupt

[PATCH] net: phy: fix auto-negotiation stall due to unavailable interrupt

[Alexander Kochetkov]

The problem I fix related to SMSC LAN8710/LAN8720 PHY handled using
interrupts. During power-up cycle the PHY do auto-negotiation, generate
interrupt and set BMSR_ANEGCOMPLETE flag. Interrupt is handled by PHY
state machine but doesn't update link because PHY is in PHY_READY state.
After some time MAC bring up and connect with PHY. It start PHY using
phy_start(). During startup PHY change state to PHY_AN but doesn't
set BMCR_ANRESTART flag due to genphy_config_aneg() doesn't update MII_BMCR
because there no new to advertising. As a result, state machine wait for
interrupt from PHY and nether get "link is up". Because BMSR_ANEGCOMPLETE
already set the patch schedule check link without waiting interrupt.
In case genphy_config_aneg() update MII_BMCR and set BMCR_ANRESTART
flag, BMSR_ANEGCOMPLETE will be cleared and state machine will continue
on auto-negotiation interrupt.

Signed-off-by: Alexander Kochetkov <al.kochet@gmail.com>
---
 drivers/net/phy/phy.c |   12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/net/phy/phy.c b/drivers/net/phy/phy.c
index 7cc1b7d..da8f03d 100644
--- a/drivers/net/phy/phy.c
+++ b/drivers/net/phy/phy.c
@@ -1169,6 +1169,18 @@ void phy_state_machine(struct work_struct *work)
 	if (phydev->irq == PHY_POLL)
 		queue_delayed_work(system_power_efficient_wq, &phydev->state_queue,
 				   PHY_STATE_TIME * HZ);
+
+	/* Re-schedule a PHY state machine to check PHY status because
+	 * negotiation already done and aneg interrupt may not be generated.
+	 */
+	if (needs_aneg && (phydev->irq > 0) && (phydev->state == PHY_AN)) {
+		err = phy_aneg_done(phydev);
+		if (err > 0)
+			queue_delayed_work(system_power_efficient_wq,
+					   &phydev->state_queue, 0);
+		if (err < 0)
+			phy_error(phydev);
+	}
 }
 
 /**
-- 
1.7.9.5

Re: [PATCH] net: phy: fix auto-negotiation stall due to unavailable interrupt

[Alexander Kochetkov]

Just found similar problem fixed in another PHY. See commit 99f81afc139c
("phy: micrel: Disable auto negotiation on startup»)

> 19 апр. 2017 г., в 16:46, Alexander Kochetkov <al.kochet@gmail.com> написал(а):
> 
> The problem I fix related to SMSC LAN8710/LAN8720 PHY handled using
> interrupts. During power-up cycle the PHY do auto-negotiation, generate
> interrupt and set BMSR_ANEGCOMPLETE flag. Interrupt is handled by PHY
> state machine but doesn't update link because PHY is in PHY_READY state.
> After some time MAC bring up and connect with PHY. It start PHY using
> phy_start(). During startup PHY change state to PHY_AN but doesn't
> set BMCR_ANRESTART flag due to genphy_config_aneg() doesn't update MII_BMCR
> because there no new to advertising. As a result, state machine wait for
> interrupt from PHY and nether get "link is up". Because BMSR_ANEGCOMPLETE
> already set the patch schedule check link without waiting interrupt.
> In case genphy_config_aneg() update MII_BMCR and set BMCR_ANRESTART
> flag, BMSR_ANEGCOMPLETE will be cleared and state machine will continue
> on auto-negotiation interrupt.
> 
> Signed-off-by: Alexander Kochetkov <al.kochet@gmail.com>
> ---
> drivers/net/phy/phy.c |   12 ++++++++++++
> 1 file changed, 12 insertions(+)
> 
> diff --git a/drivers/net/phy/phy.c b/drivers/net/phy/phy.c
> index 7cc1b7d..da8f03d 100644
> --- a/drivers/net/phy/phy.c
> +++ b/drivers/net/phy/phy.c
> @@ -1169,6 +1169,18 @@ void phy_state_machine(struct work_struct *work)
> 	if (phydev->irq == PHY_POLL)
> 		queue_delayed_work(system_power_efficient_wq, &phydev->state_queue,
> 				   PHY_STATE_TIME * HZ);
> +
> +	/* Re-schedule a PHY state machine to check PHY status because
> +	 * negotiation already done and aneg interrupt may not be generated.
> +	 */
> +	if (needs_aneg && (phydev->irq > 0) && (phydev->state == PHY_AN)) {
> +		err = phy_aneg_done(phydev);
> +		if (err > 0)
> +			queue_delayed_work(system_power_efficient_wq,
> +					   &phydev->state_queue, 0);
> +		if (err < 0)
> +			phy_error(phydev);
> +	}
> }
> 
> /**
> -- 
> 1.7.9.5
> 

Re: [PATCH] net: phy: fix auto-negotiation stall due to unavailable interrupt

[Florian Fainelli]

On 04/19/2017 07:05 AM, Alexander Kochetkov wrote:
> Just found similar problem fixed in another PHY. See commit 99f81afc139c
> ("phy: micrel: Disable auto negotiation on startup»)

This specific commit was really a "this works for me, but I have not
investigated what needs fixing in PHYLIB".

Roger has been submitting a couple of patches to fix the same issue and
yours seems to be better in that it also addresses his concerns that
after his fix there was still a 1s delay (the HZ parameter to the
queue_delayed_work call) being seen:

http://patchwork.ozlabs.org/patch/743773/

Roger can you also test Alexander's patch?

> 
>> 19 апр. 2017 г., в 16:46, Alexander Kochetkov <al.kochet@gmail.com> написал(а):
>>
>> The problem I fix related to SMSC LAN8710/LAN8720 PHY handled using
>> interrupts. During power-up cycle the PHY do auto-negotiation, generate
>> interrupt and set BMSR_ANEGCOMPLETE flag. Interrupt is handled by PHY
>> state machine but doesn't update link because PHY is in PHY_READY state.
>> After some time MAC bring up and connect with PHY. It start PHY using
>> phy_start(). During startup PHY change state to PHY_AN but doesn't
>> set BMCR_ANRESTART flag due to genphy_config_aneg() doesn't update MII_BMCR
>> because there no new to advertising. As a result, state machine wait for
>> interrupt from PHY and nether get "link is up". Because BMSR_ANEGCOMPLETE
>> already set the patch schedule check link without waiting interrupt.
>> In case genphy_config_aneg() update MII_BMCR and set BMCR_ANRESTART
>> flag, BMSR_ANEGCOMPLETE will be cleared and state machine will continue
>> on auto-negotiation interrupt.
>>
>> Signed-off-by: Alexander Kochetkov <al.kochet@gmail.com>
>> ---
>> drivers/net/phy/phy.c |   12 ++++++++++++
>> 1 file changed, 12 insertions(+)
>>
>> diff --git a/drivers/net/phy/phy.c b/drivers/net/phy/phy.c
>> index 7cc1b7d..da8f03d 100644
>> --- a/drivers/net/phy/phy.c
>> +++ b/drivers/net/phy/phy.c
>> @@ -1169,6 +1169,18 @@ void phy_state_machine(struct work_struct *work)
>> 	if (phydev->irq == PHY_POLL)
>> 		queue_delayed_work(system_power_efficient_wq, &phydev->state_queue,
>> 				   PHY_STATE_TIME * HZ);
>> +
>> +	/* Re-schedule a PHY state machine to check PHY status because
>> +	 * negotiation already done and aneg interrupt may not be generated.
>> +	 */
>> +	if (needs_aneg && (phydev->irq > 0) && (phydev->state == PHY_AN)) {
>> +		err = phy_aneg_done(phydev);
>> +		if (err > 0)
>> +			queue_delayed_work(system_power_efficient_wq,
>> +					   &phydev->state_queue, 0);
>> +		if (err < 0)
>> +			phy_error(phydev);
>> +	}
>> }
>>
>> /**
>> -- 
>> 1.7.9.5
>>
> 


-- 
Florian

Re: [PATCH] net: phy: fix auto-negotiation stall due to unavailable interrupt

[Alexander Kochetkov]

> 19 апр. 2017 г., в 19:32, Florian Fainelli <f.fainelli@gmail.com> написал(а):
> 
> http://patchwork.ozlabs.org/patch/743773/
> 
> Roger can you also test Alexander's patch?

If MAC use phy_start_aneg() instead of phy_start() my patch will not work as
expected. Roger, if patch don’t work for you please check what MAC bring up PHY using
phy_start():

http://patchwork.ozlabs.org/patch/752308/

Is it correct to start PHY inside MAC probe using phy_start_aneg()? Or phy_start() must be used?

And probably this tags should be added for my patch:
Fixes: 3c293f4e08b5 ("net: phy: Trigger state machine on state change and not polling.")
Cc: stable <stable@vger.kernel.org> # v4.9+

Because I bisected to commit 529ed1275263 ("net: phy: phy drivers
should not set SUPPORTED_[Asym_]Pause») that looks pretty good.

Also, there is another issue I found. link_timeout doesn’t work for interrupt driven PHY.
It is possible to implement timer to handle this case.
Florian, what do you think? Should this be fixed?

Alexander.

Re: [PATCH] net: phy: fix auto-negotiation stall due to unavailable interrupt

[Sergei Shtylyov]

Hello!

On 04/19/2017 04:46 PM, Alexander Kochetkov wrote:

> The problem I fix related to SMSC LAN8710/LAN8720 PHY handled using
> interrupts. During power-up cycle the PHY do auto-negotiation, generate
> interrupt and set BMSR_ANEGCOMPLETE flag. Interrupt is handled by PHY
> state machine but doesn't update link because PHY is in PHY_READY state.
> After some time MAC bring up and connect with PHY. It start PHY using
> phy_start(). During startup PHY change state to PHY_AN but doesn't
> set BMCR_ANRESTART flag due to genphy_config_aneg() doesn't update MII_BMCR
> because there no new to advertising. As a result, state machine wait for
           ^^^^^^^^^^^^    ^^^^^^^^^^^
    There is no new what? Advertize, maybe?

> interrupt from PHY and nether get "link is up". Because BMSR_ANEGCOMPLETE
                          ^^^^^^
    Never, neither? :-)

> already set the patch schedule check link without waiting interrupt.
> In case genphy_config_aneg() update MII_BMCR and set BMCR_ANRESTART
> flag, BMSR_ANEGCOMPLETE will be cleared and state machine will continue
> on auto-negotiation interrupt.
>
> Signed-off-by: Alexander Kochetkov <al.kochet@gmail.com>
[...]

MBR, Sergei

Re: [PATCH] net: phy: fix auto-negotiation stall due to unavailable interrupt

[Roger Quadros]

Hi,

On 19/04/17 19:53, Alexander Kochetkov wrote:
> 
>> 19 апр. 2017 г., в 19:32, Florian Fainelli <f.fainelli@gmail.com> написал(а):
>>
>> http://patchwork.ozlabs.org/patch/743773/
>>
>> Roger can you also test Alexander's patch?

This patch fixes my problem and doesn't have the 1 second delay that my patch had.

So,

Tested-by: Roger Quadros <rogerq@ti.com>

> 
> If MAC use phy_start_aneg() instead of phy_start() my patch will not work as
> expected. Roger, if patch don’t work for you please check what MAC bring up PHY using
> phy_start():

Our MAC driver is using phy_start() and I didn't face any issues with your patch.

> 
> http://patchwork.ozlabs.org/patch/752308/
> 
> Is it correct to start PHY inside MAC probe using phy_start_aneg()? Or phy_start() must be used?
> 
> And probably this tags should be added for my patch:
> Fixes: 3c293f4e08b5 ("net: phy: Trigger state machine on state change and not polling.")
> Cc: stable <stable@vger.kernel.org> # v4.9+
> 
> Because I bisected to commit 529ed1275263 ("net: phy: phy drivers
> should not set SUPPORTED_[Asym_]Pause») that looks pretty good.
> 
> Also, there is another issue I found. link_timeout doesn’t work for interrupt driven PHY.
> It is possible to implement timer to handle this case.
> Florian, what do you think? Should this be fixed?
> 
> Alexander.
> 

cheers,
-roger