[PATCH net] net: micrel: Fix lan8841_config_intr after getting out of sleep mode

[PATCH net] net: micrel: Fix lan8841_config_intr after getting out of sleep mode

[Horatiu Vultur]

When the interrupt is enabled, the function lan8841_config_intr tries to
clear any pending interrupts by reading the interrupt status, then
checks the return value for errors and then continue to enable the
interrupt. It has been seen that once the system gets out of sleep mode,
the interrupt status has the value 0x400 meaning that the PHY detected
that the link was in low power. That is correct value but the problem is
that the check is wrong.  We try to check for errors but we return an
error also in this case which is not an error. Therefore fix this by
returning only when there is an error.

Fixes: a8f1a19d27ef ("net: micrel: Add support for lan8841 PHY")
Signed-off-by: Horatiu Vultur <horatiu.vultur@microchip.com>
---
 drivers/net/phy/micrel.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/phy/micrel.c b/drivers/net/phy/micrel.c
index 13e30ea7eec5d..79477f0c90d82 100644
--- a/drivers/net/phy/micrel.c
+++ b/drivers/net/phy/micrel.c
@@ -4029,7 +4029,7 @@ static int lan8841_config_intr(struct phy_device *phydev)
 
 	if (phydev->interrupts == PHY_INTERRUPT_ENABLED) {
 		err = phy_read(phydev, LAN8814_INTS);
-		if (err)
+		if (err < 0)
 			return err;
 
 		/* Enable / disable interrupts. It is OK to enable PTP interrupt
-- 
2.34.1

Re: [PATCH net] net: micrel: Fix lan8841_config_intr after getting out of sleep mode

[Andrew Lunn]

On Thu, May 23, 2024 at 09:42:26AM +0200, Horatiu Vultur wrote:
> When the interrupt is enabled, the function lan8841_config_intr tries to
> clear any pending interrupts by reading the interrupt status, then
> checks the return value for errors and then continue to enable the
> interrupt. It has been seen that once the system gets out of sleep mode,
> the interrupt status has the value 0x400 meaning that the PHY detected
> that the link was in low power. That is correct value but the problem is
> that the check is wrong.  We try to check for errors but we return an
> error also in this case which is not an error. Therefore fix this by
> returning only when there is an error.

Is the second case also broken in the same way?

	} else {
		err = phy_write(phydev, LAN8814_INTC, 0);
		if (err)
			return err;

		err = phy_read(phydev, LAN8814_INTS);
	}

	return err;

e.g. there was an outstanding interrupt as interrupts are
disabled. This will cause the return value of the function to be not
0?

	Andrew

RE: [EXTERNAL] [PATCH net] net: micrel: Fix lan8841_config_intr after getting out of sleep mode

[Suman Ghosh]

> 	if (phydev->interrupts == PHY_INTERRUPT_ENABLED) {
> 		err = phy_read(phydev, LAN8814_INTS);
>-		if (err)
>+		if (err < 0)
[Suman] Hi Horatiu,
Should we modify this check for phy_write() as well?
> 			return err;
>
> 		/* Enable / disable interrupts. It is OK to enable PTP
>interrupt
>--
>2.34.1
>

Re: [PATCH net] net: micrel: Fix lan8841_config_intr after getting out of sleep mode

[Horatiu Vultur]

The 05/23/2024 16:32, Andrew Lunn wrote:

Hi Andrew,

> 
> On Thu, May 23, 2024 at 09:42:26AM +0200, Horatiu Vultur wrote:
> > When the interrupt is enabled, the function lan8841_config_intr tries to
> > clear any pending interrupts by reading the interrupt status, then
> > checks the return value for errors and then continue to enable the
> > interrupt. It has been seen that once the system gets out of sleep mode,
> > the interrupt status has the value 0x400 meaning that the PHY detected
> > that the link was in low power. That is correct value but the problem is
> > that the check is wrong.  We try to check for errors but we return an
> > error also in this case which is not an error. Therefore fix this by
> > returning only when there is an error.
> 
> Is the second case also broken in the same way?
> 
>         } else {
>                 err = phy_write(phydev, LAN8814_INTC, 0);
>                 if (err)
>                         return err;
> 
>                 err = phy_read(phydev, LAN8814_INTS);
>         }
> 
>         return err;
> 
> e.g. there was an outstanding interrupt as interrupts are
> disabled. This will cause the return value of the function to be not
> 0?

Yes, that is correct. In that case, it would return some positive number
which is the status, which is incorrect.
I will fix this in the new version.

> 
>         Andrew

-- 
/Horatiu

Re: [PATCH net] net: micrel: Fix lan8841_config_intr after getting out of sleep mode

[Horatiu Vultur]

The 05/23/2024 16:35, Suman Ghosh wrote:

Hi Suman,

> 
> >       if (phydev->interrupts == PHY_INTERRUPT_ENABLED) {
> >               err = phy_read(phydev, LAN8814_INTS);
> >-              if (err)
> >+              if (err < 0)
> [Suman] Hi Horatiu,
> Should we modify this check for phy_write() as well?

I don't think we should modify this check for phy_write.
Because phy_write always return the error code. Which is negative or 0.

> >                       return err;
> >
> >               /* Enable / disable interrupts. It is OK to enable PTP
> >interrupt
> >--
> >2.34.1
> >
> 

-- 
/Horatiu