diff mbox series

[net-next,v2,06/10] net: phy: print an info if a broken C45 bus is found

Message ID 20230620-feature-c45-over-c22-v2-6-def0ab9ccee2@kernel.org
State New
Headers
Series net: phy: C45-over-C22 access |

Commit Message

Michael Walle June 23, 2023, 10:29 a.m. UTC 
  If there is an PHY which gets confused by C45 transactions on the MDIO
bus, print an info together with the PHY identifier of the offending
one.

Signed-off-by: Michael Walle <mwalle@kernel.org>

---
I wasn't sure if this should be phydev_dbg() or phydev_info(). I mainly
see this as an info to a user why some PHYs might not be probed (or
c45-over-c22 is used later).
---
 drivers/net/phy/mdio_bus.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

Comments

Andrew Lunn June 23, 2023, 5:42 p.m. UTC | #1 
On Fri, Jun 23, 2023 at 12:29:15PM +0200, Michael Walle wrote:
> If there is an PHY which gets confused by C45 transactions on the MDIO
> bus, print an info together with the PHY identifier of the offending
> one.
> 
> Signed-off-by: Michael Walle <mwalle@kernel.org>
> 
> ---
> I wasn't sure if this should be phydev_dbg() or phydev_info(). I mainly
> see this as an info to a user why some PHYs might not be probed (or
> c45-over-c22 is used later).

The information is useful to the DT writer, not the 'user'. I would
assume the DT writer has a bit more kernel knowledge and can debug
prints on. So i would suggest phydev_dbg().

> @@ -617,10 +617,10 @@ static int mdiobus_scan_bus_c45(struct mii_bus *bus)
>   */
>  void mdiobus_scan_for_broken_c45_access(struct mii_bus *bus)
>  {
> +	struct phy_device *phydev;
>  	int i;
>  
>  	for (i = 0; i < PHY_MAX_ADDR; i++) {
> -		struct phy_device *phydev;
>  		u32 oui;

It is not clear why you changed the scope of phydev. I guess another
version used phydev_info(), where as now you have dev_info()?

	Andrew

>  
>  		phydev = mdiobus_get_phy(bus, i);
> @@ -633,6 +633,11 @@ void mdiobus_scan_for_broken_c45_access(struct mii_bus *bus)
>  			break;
>  		}
>  	}
> +
> +	if (bus->prevent_c45_access)
> +		dev_info(&bus->dev,
> +			 "Detected broken PHY (ID %08lx). Disabling C45 bus transactions.\n",
> +			 (unsigned long)phydev->phy_id);
>  }
>  
>  /**
> 
> -- 
> 2.39.2
>
Simon Horman June 23, 2023, 8:35 p.m. UTC | #2 
On Fri, Jun 23, 2023 at 07:42:08PM +0200, Andrew Lunn wrote:
> On Fri, Jun 23, 2023 at 12:29:15PM +0200, Michael Walle wrote:
> > If there is an PHY which gets confused by C45 transactions on the MDIO
> > bus, print an info together with the PHY identifier of the offending
> > one.
> > 
> > Signed-off-by: Michael Walle <mwalle@kernel.org>
> > 
> > ---
> > I wasn't sure if this should be phydev_dbg() or phydev_info(). I mainly
> > see this as an info to a user why some PHYs might not be probed (or
> > c45-over-c22 is used later).
> 
> The information is useful to the DT writer, not the 'user'. I would
> assume the DT writer has a bit more kernel knowledge and can debug
> prints on. So i would suggest phydev_dbg().
> 
> > @@ -617,10 +617,10 @@ static int mdiobus_scan_bus_c45(struct mii_bus *bus)
> >   */
> >  void mdiobus_scan_for_broken_c45_access(struct mii_bus *bus)
> >  {
> > +	struct phy_device *phydev;
> >  	int i;
> >  
> >  	for (i = 0; i < PHY_MAX_ADDR; i++) {
> > -		struct phy_device *phydev;
> >  		u32 oui;
> 
> It is not clear why you changed the scope of phydev. I guess another
> version used phydev_info(), where as now you have dev_info()?

I think it is so it can be used in the dev_info() call below.
However Smatch has it's doubts that it is always initialised there.

  .../mdio_bus.c:638 mdiobus_scan_for_broken_c45_access() error: we previously assumed 'phydev' could be null (see line 627)

> >  		phydev = mdiobus_get_phy(bus, i);

Line 627 immediately follows the line above, like this:

		if (!phydev)
			continue;

> > @@ -633,6 +633,11 @@ void mdiobus_scan_for_broken_c45_access(struct mii_bus *bus)
> >  			break;
> >  		}
> >  	}
> > +
> > +	if (bus->prevent_c45_access)
> > +		dev_info(&bus->dev,
> > +			 "Detected broken PHY (ID %08lx). Disabling C45 bus transactions.\n",
> > +			 (unsigned long)phydev->phy_id);
> >  }
> >  
> >  /**
> > 
> > -- 
> > 2.39.2
> > 
>
Michael Walle June 26, 2023, 6:50 a.m. UTC | #3 
Am 2023-06-23 22:35, schrieb Simon Horman:
> On Fri, Jun 23, 2023 at 07:42:08PM +0200, Andrew Lunn wrote:
>> On Fri, Jun 23, 2023 at 12:29:15PM +0200, Michael Walle wrote:
>> > If there is an PHY which gets confused by C45 transactions on the MDIO
>> > bus, print an info together with the PHY identifier of the offending
>> > one.
>> >
>> > Signed-off-by: Michael Walle <mwalle@kernel.org>
>> >
>> > ---
>> > I wasn't sure if this should be phydev_dbg() or phydev_info(). I mainly
>> > see this as an info to a user why some PHYs might not be probed (or
>> > c45-over-c22 is used later).
>> 
>> The information is useful to the DT writer, not the 'user'. I would
>> assume the DT writer has a bit more kernel knowledge and can debug
>> prints on. So i would suggest phydev_dbg().

Why the DT writer? There could be no DT at all, right? But yeah, fair
enough, I thought of our hardware engineers as a user, which might be
surprised to find no C45 transactions at all for a C45 PHY.

That said, I don't have a strong opinion. I'm fine to switch that to
dev_dbg() to make the kernel output less noisy.

>> > @@ -617,10 +617,10 @@ static int mdiobus_scan_bus_c45(struct mii_bus *bus)
>> >   */
>> >  void mdiobus_scan_for_broken_c45_access(struct mii_bus *bus)
>> >  {
>> > +	struct phy_device *phydev;
>> >  	int i;
>> >
>> >  	for (i = 0; i < PHY_MAX_ADDR; i++) {
>> > -		struct phy_device *phydev;
>> >  		u32 oui;
>> 
>> It is not clear why you changed the scope of phydev. I guess another
>> version used phydev_info(), where as now you have dev_info()?
> 
> I think it is so it can be used in the dev_info() call below.

Yes, to print the PHY ID of the offending one.

> However Smatch has it's doubts that it is always initialised there.
> 
>   .../mdio_bus.c:638 mdiobus_scan_for_broken_c45_access() error: we 
> previously assumed 'phydev' could be null (see line 627)
> 
>> >  		phydev = mdiobus_get_phy(bus, i);
> 
> Line 627 immediately follows the line above, like this:
> 
> 		if (!phydev)
> 			continue;

Mhh, I see. bus->prevent_c45_access could (theoretically) set before
calling this function. I could set it to false at the beginning of
this function or I could use a new flag to indicate when to print the
warning. Any suggestions?

-michael
diff mbox series

Patch

diff --git a/drivers/net/phy/mdio_bus.c b/drivers/net/phy/mdio_bus.c
index 00b25f6803bc..38529add6420 100644
--- a/drivers/net/phy/mdio_bus.c
+++ b/drivers/net/phy/mdio_bus.c
@@ -617,10 +617,10 @@  static int mdiobus_scan_bus_c45(struct mii_bus *bus)
  */
 void mdiobus_scan_for_broken_c45_access(struct mii_bus *bus)
 {
+	struct phy_device *phydev;
 	int i;
 
 	for (i = 0; i < PHY_MAX_ADDR; i++) {
-		struct phy_device *phydev;
 		u32 oui;
 
 		phydev = mdiobus_get_phy(bus, i);
@@ -633,6 +633,11 @@  void mdiobus_scan_for_broken_c45_access(struct mii_bus *bus)
 			break;
 		}
 	}
+
+	if (bus->prevent_c45_access)
+		dev_info(&bus->dev,
+			 "Detected broken PHY (ID %08lx). Disabling C45 bus transactions.\n",
+			 (unsigned long)phydev->phy_id);
 }
 
 /**