Re: [PATCH net 2/2] net: phy: Check harder for errors in get_phy_id()
On 6/19/2020 6:30 AM, Russell King - ARM Linux admin wrote:
> On Fri, Jun 19, 2020 at 03:26:59PM +0200, Andrew Lunn wrote:
>> On Thu, Jun 18, 2020 at 09:47:59PM -0700, Florian Fainelli wrote:
>>> Commit 02a6efcab675 ("net: phy: allow scanning busses with missing
>>> phys") added a special condition to return -ENODEV in case -ENODEV or
>>> -EIO was returned from the first read of the MII_PHYSID1 register.
>>>
>>> In case the MDIO bus data line pull-up is not strong enough, the MDIO
>>> bus controller will not flag this as a read error. This can happen when
>>> a pluggable daughter card is not connected and weak internal pull-ups
>>> are used (since that is the only option, otherwise the pins are
>>> floating).
>>>
>>> The second read of MII_PHYSID2 will be correctly flagged an error
>>> though, but now we will return -EIO which will be treated as a hard
>>> error, thus preventing MDIO bus scanning loops to continue succesfully.
>>>
>>> Apply the same logic to both register reads, thus allowing the scanning
>>> logic to proceed.
>>
>> Hi Florian
>>
>> Maybe extend the kerneldoc for this function to document the return
>> values and there special meanings?
>
> You mean like the patch I sent yesterday?
>
>> BTW: Did you look at get_phy_c45_ids()? Is it using the correct return
>> value? Given the current work being done to extend scanning to C45,
>> maybe it needs reviewing for issues like this.
>
> And the updates I sent for this yesterday? ;)
When Russell's patches land, they will address this correctly and
because I did not want to introduce any conflicts, this is not addressed
by this two patch series.
--
Florian
Re: [PATCH net 2/2] net: phy: Check harder for errors in get_phy_id()
On Fri, Jun 19, 2020 at 03:26:59PM +0200, Andrew Lunn wrote:
> On Thu, Jun 18, 2020 at 09:47:59PM -0700, Florian Fainelli wrote:
> > Commit 02a6efcab675 ("net: phy: allow scanning busses with missing
> > phys") added a special condition to return -ENODEV in case -ENODEV or
> > -EIO was returned from the first read of the MII_PHYSID1 register.
> >
> > In case the MDIO bus data line pull-up is not strong enough, the MDIO
> > bus controller will not flag this as a read error. This can happen when
> > a pluggable daughter card is not connected and weak internal pull-ups
> > are used (since that is the only option, otherwise the pins are
> > floating).
> >
> > The second read of MII_PHYSID2 will be correctly flagged an error
> > though, but now we will return -EIO which will be treated as a hard
> > error, thus preventing MDIO bus scanning loops to continue succesfully.
> >
> > Apply the same logic to both register reads, thus allowing the scanning
> > logic to proceed.
>
> Hi Florian
>
> Maybe extend the kerneldoc for this function to document the return
> values and there special meanings?
You mean like the patch I sent yesterday?
> BTW: Did you look at get_phy_c45_ids()? Is it using the correct return
> value? Given the current work being done to extend scanning to C45,
> maybe it needs reviewing for issues like this.
And the updates I sent for this yesterday? ;)
--
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!
Re: [PATCH net 2/2] net: phy: Check harder for errors in get_phy_id()
On Thu, Jun 18, 2020 at 09:47:59PM -0700, Florian Fainelli wrote:
> Commit 02a6efcab675 ("net: phy: allow scanning busses with missing
> phys") added a special condition to return -ENODEV in case -ENODEV or
> -EIO was returned from the first read of the MII_PHYSID1 register.
>
> In case the MDIO bus data line pull-up is not strong enough, the MDIO
> bus controller will not flag this as a read error. This can happen when
> a pluggable daughter card is not connected and weak internal pull-ups
> are used (since that is the only option, otherwise the pins are
> floating).
>
> The second read of MII_PHYSID2 will be correctly flagged an error
> though, but now we will return -EIO which will be treated as a hard
> error, thus preventing MDIO bus scanning loops to continue succesfully.
>
> Apply the same logic to both register reads, thus allowing the scanning
> logic to proceed.
Hi Florian
Maybe extend the kerneldoc for this function to document the return
values and there special meanings?
Reviewed-by: Andrew Lunn
BTW: Did you look at get_phy_c45_ids()? Is it using the correct return
value? Given the current work being done to extend scanning to C45,
maybe it needs reviewing for issues like this.
Andrew
[PATCH net 2/2] net: phy: Check harder for errors in get_phy_id()
Commit 02a6efcab675 ("net: phy: allow scanning busses with missing
phys") added a special condition to return -ENODEV in case -ENODEV or
-EIO was returned from the first read of the MII_PHYSID1 register.
In case the MDIO bus data line pull-up is not strong enough, the MDIO
bus controller will not flag this as a read error. This can happen when
a pluggable daughter card is not connected and weak internal pull-ups
are used (since that is the only option, otherwise the pins are
floating).
The second read of MII_PHYSID2 will be correctly flagged an error
though, but now we will return -EIO which will be treated as a hard
error, thus preventing MDIO bus scanning loops to continue succesfully.
Apply the same logic to both register reads, thus allowing the scanning
logic to proceed.
Fixes: 02a6efcab675 ("net: phy: allow scanning busses with missing phys")
Signed-off-by: Florian Fainelli
---
drivers/net/phy/phy_device.c | 6 --
1 file changed, 4 insertions(+), 2 deletions(-)
diff --git a/drivers/net/phy/phy_device.c b/drivers/net/phy/phy_device.c
index 04946de74fa0..85ba95b598b5 100644
--- a/drivers/net/phy/phy_device.c
+++ b/drivers/net/phy/phy_device.c
@@ -794,8 +794,10 @@ static int get_phy_id(struct mii_bus *bus, int addr, u32
*phy_id,
/* Grab the bits from PHYIR2, and put them in the lower half */
phy_reg = mdiobus_read(bus, addr, MII_PHYSID2);
- if (phy_reg < 0)
- return -EIO;
+ if (phy_reg < 0) {
+ /* returning -ENODEV doesn't stop bus scanning */
+ return (phy_reg == -EIO || phy_reg == -ENODEV) ? -ENODEV : -EIO;
+ }
*phy_id |= phy_reg;
--
2.17.1
