Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1599714 > unrolled thread

[PATCH net-next] net: dsa: mv88e6xxx: debug ATU Age Time

Back to article view | Back to linux.kernel

Contents

  [PATCH net-next] net: dsa: mv88e6xxx: debug ATU Age Time Vivien Didelot <vivien.didelot@savoirfairelinux.com> - 2017-03-13 20:30 +0100
    Re: [PATCH net-next] net: dsa: mv88e6xxx: debug ATU Age Time Andrew Lunn <andrew@lunn.ch> - 2017-03-13 23:40 +0100
      Re: [PATCH net-next] net: dsa: mv88e6xxx: debug ATU Age Time Florian Fainelli <f.fainelli@gmail.com> - 2017-03-13 23:50 +0100
        Re: [PATCH net-next] net: dsa: mv88e6xxx: debug ATU Age Time Andrew Lunn <andrew@lunn.ch> - 2017-03-14 00:00 +0100
          Re: [PATCH net-next] net: dsa: mv88e6xxx: debug ATU Age Time Matthias May <matthias.may@neratec.com> - 2017-03-14 12:20 +0100
            Re: [PATCH net-next] net: dsa: mv88e6xxx: debug ATU Age Time Andrew Lunn <andrew@lunn.ch> - 2017-03-14 13:10 +0100
              Re: [PATCH net-next] net: dsa: mv88e6xxx: debug ATU Age Time Vivien Didelot <vivien.didelot@savoirfairelinux.com> - 2017-03-14 15:10 +0100
                Re: [PATCH net-next] net: dsa: mv88e6xxx: debug ATU Age Time Andrew Lunn <andrew@lunn.ch> - 2017-03-14 15:20 +0100

#1599714 — [PATCH net-next] net: dsa: mv88e6xxx: debug ATU Age Time

The ATU ageing time value programmed in the switch is rounded up to the
nearest multiple of its coefficient (variable depending on the model.)

Add a debug message to inform the user about the exact programmed value.

On 6352, "brctl setageing br0 18" gives "AgeTime set to 0x01 (15000 ms)"
while on 6390 we get "AgeTime set to 0x05 (18750 ms)".

Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
---
 drivers/net/dsa/mv88e6xxx/global1_atu.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/drivers/net/dsa/mv88e6xxx/global1_atu.c b/drivers/net/dsa/mv88e6xxx/global1_atu.c
index f6cd3c939da4..bac34737b096 100644
--- a/drivers/net/dsa/mv88e6xxx/global1_atu.c
+++ b/drivers/net/dsa/mv88e6xxx/global1_atu.c
@@ -65,7 +65,14 @@ int mv88e6xxx_g1_atu_set_age_time(struct mv88e6xxx_chip *chip,
 	val &= ~0xff0;
 	val |= age_time << 4;
 
-	return mv88e6xxx_g1_write(chip, GLOBAL_ATU_CONTROL, val);
+	err = mv88e6xxx_g1_write(chip, GLOBAL_ATU_CONTROL, val);
+	if (err)
+		return err;
+
+	dev_dbg(chip->dev, "AgeTime set to 0x%02x (%d ms)\n", age_time,
+		age_time * coeff);
+
+	return 0;
 }
 
 /* Offset 0x0B: ATU Operation Register */
-- 
2.12.0

[toc] | [next] | [standalone]

#1599896

On Mon, Mar 13, 2017 at 03:20:43PM -0400, Vivien Didelot wrote:
> The ATU ageing time value programmed in the switch is rounded up to the
> nearest multiple of its coefficient (variable depending on the model.)
> 
> Add a debug message to inform the user about the exact programmed value.
> 
> On 6352, "brctl setageing br0 18" gives "AgeTime set to 0x01 (15000 ms)"
> while on 6390 we get "AgeTime set to 0x05 (18750 ms)".
> 
> Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
> ---
>  drivers/net/dsa/mv88e6xxx/global1_atu.c | 9 ++++++++-
>  1 file changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/net/dsa/mv88e6xxx/global1_atu.c b/drivers/net/dsa/mv88e6xxx/global1_atu.c
> index f6cd3c939da4..bac34737b096 100644
> --- a/drivers/net/dsa/mv88e6xxx/global1_atu.c
> +++ b/drivers/net/dsa/mv88e6xxx/global1_atu.c
> @@ -65,7 +65,14 @@ int mv88e6xxx_g1_atu_set_age_time(struct mv88e6xxx_chip *chip,
>  	val &= ~0xff0;
>  	val |= age_time << 4;
>  
> -	return mv88e6xxx_g1_write(chip, GLOBAL_ATU_CONTROL, val);
> +	err = mv88e6xxx_g1_write(chip, GLOBAL_ATU_CONTROL, val);
> +	if (err)
> +		return err;
> +
> +	dev_dbg(chip->dev, "AgeTime set to 0x%02x (%d ms)\n", age_time,
> +		age_time * coeff);
> +

Hi Vivien

You could put the dev_dbg before the mv88e6xxx_g1_write(), to keep the
code simpler. If this write fails, we expect a lot of other things to
go horribly wrong, so having one debug message being not quite accurate
is not important.

   Andrew

[toc] | [prev] | [next] | [standalone]

#1599904

On 03/13/2017 03:39 PM, Andrew Lunn wrote:
> On Mon, Mar 13, 2017 at 03:20:43PM -0400, Vivien Didelot wrote:
>> The ATU ageing time value programmed in the switch is rounded up to the
>> nearest multiple of its coefficient (variable depending on the model.)
>>
>> Add a debug message to inform the user about the exact programmed value.
>>
>> On 6352, "brctl setageing br0 18" gives "AgeTime set to 0x01 (15000 ms)"
>> while on 6390 we get "AgeTime set to 0x05 (18750 ms)".
>>
>> Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
>> ---
>>  drivers/net/dsa/mv88e6xxx/global1_atu.c | 9 ++++++++-
>>  1 file changed, 8 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/net/dsa/mv88e6xxx/global1_atu.c b/drivers/net/dsa/mv88e6xxx/global1_atu.c
>> index f6cd3c939da4..bac34737b096 100644
>> --- a/drivers/net/dsa/mv88e6xxx/global1_atu.c
>> +++ b/drivers/net/dsa/mv88e6xxx/global1_atu.c
>> @@ -65,7 +65,14 @@ int mv88e6xxx_g1_atu_set_age_time(struct mv88e6xxx_chip *chip,
>>  	val &= ~0xff0;
>>  	val |= age_time << 4;
>>  
>> -	return mv88e6xxx_g1_write(chip, GLOBAL_ATU_CONTROL, val);
>> +	err = mv88e6xxx_g1_write(chip, GLOBAL_ATU_CONTROL, val);
>> +	if (err)
>> +		return err;
>> +
>> +	dev_dbg(chip->dev, "AgeTime set to 0x%02x (%d ms)\n", age_time,
>> +		age_time * coeff);
>> +
> 
> Hi Vivien
> 
> You could put the dev_dbg before the mv88e6xxx_g1_write(), to keep the
> code simpler. If this write fails, we expect a lot of other things to
> go horribly wrong, so having one debug message being not quite accurate
> is not important.

The debug message would not be printed in case mv88e6xxx_g1_write()
fails, also, having the message printed after the write occurred is a
good way to make sure the write did make it through. Did I miss
something in what you are suggesting here?
-- 
Florian

[toc] | [prev] | [next] | [standalone]

#1599906

On Mon, Mar 13, 2017 at 03:42:36PM -0700, Florian Fainelli wrote:
> On 03/13/2017 03:39 PM, Andrew Lunn wrote:
> > On Mon, Mar 13, 2017 at 03:20:43PM -0400, Vivien Didelot wrote:
> >> The ATU ageing time value programmed in the switch is rounded up to the
> >> nearest multiple of its coefficient (variable depending on the model.)
> >>
> >> Add a debug message to inform the user about the exact programmed value.
> >>
> >> On 6352, "brctl setageing br0 18" gives "AgeTime set to 0x01 (15000 ms)"
> >> while on 6390 we get "AgeTime set to 0x05 (18750 ms)".
> >>
> >> Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
> >> ---
> >>  drivers/net/dsa/mv88e6xxx/global1_atu.c | 9 ++++++++-
> >>  1 file changed, 8 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/drivers/net/dsa/mv88e6xxx/global1_atu.c b/drivers/net/dsa/mv88e6xxx/global1_atu.c
> >> index f6cd3c939da4..bac34737b096 100644
> >> --- a/drivers/net/dsa/mv88e6xxx/global1_atu.c
> >> +++ b/drivers/net/dsa/mv88e6xxx/global1_atu.c
> >> @@ -65,7 +65,14 @@ int mv88e6xxx_g1_atu_set_age_time(struct mv88e6xxx_chip *chip,
> >>  	val &= ~0xff0;
> >>  	val |= age_time << 4;
> >>  
> >> -	return mv88e6xxx_g1_write(chip, GLOBAL_ATU_CONTROL, val);
> >> +	err = mv88e6xxx_g1_write(chip, GLOBAL_ATU_CONTROL, val);
> >> +	if (err)
> >> +		return err;
> >> +
> >> +	dev_dbg(chip->dev, "AgeTime set to 0x%02x (%d ms)\n", age_time,
> >> +		age_time * coeff);
> >> +
> > 
> > Hi Vivien
> > 
> > You could put the dev_dbg before the mv88e6xxx_g1_write(), to keep the
> > code simpler. If this write fails, we expect a lot of other things to
> > go horribly wrong, so having one debug message being not quite accurate
> > is not important.
> 
> The debug message would not be printed in case mv88e6xxx_g1_write()
> fails, also, having the message printed after the write occurred is a
> good way to make sure the write did make it through. Did I miss
> something in what you are suggesting here?

We never, ever see a read or a write failure on the MDIO bus. If it
ever does, i expect the switch is dead, gone, never to be heard from
again until the power is reset. We are going to have lots of
failures. So it seems simpler to have:

	dev_dbg(chip->dev, "Setting AgeTime to 0x%02x (%d ms)\n", age_time,
		age_time * coeff);

	return mv88e6xxx_g1_write(chip, GLOBAL_ATU_CONTROL, val);

and accept that if for some unlikely reason the write does fail, the
debug message is probably not accurate.

      Andrew

[toc] | [prev] | [next] | [standalone]

#1600232

On 13/03/17 23:58, Andrew Lunn wrote:
> On Mon, Mar 13, 2017 at 03:42:36PM -0700, Florian Fainelli wrote:
>> On 03/13/2017 03:39 PM, Andrew Lunn wrote:
>>> On Mon, Mar 13, 2017 at 03:20:43PM -0400, Vivien Didelot wrote:
>>>> The ATU ageing time value programmed in the switch is rounded up to the
>>>> nearest multiple of its coefficient (variable depending on the model.)
>>>>
>>>> Add a debug message to inform the user about the exact programmed value.
>>>>
>>>> On 6352, "brctl setageing br0 18" gives "AgeTime set to 0x01 (15000 ms)"
>>>> while on 6390 we get "AgeTime set to 0x05 (18750 ms)".
>>>>
>>>> Signed-off-by: Vivien Didelot <vivien.didelot@savoirfairelinux.com>
>>>> ---
>>>>  drivers/net/dsa/mv88e6xxx/global1_atu.c | 9 ++++++++-
>>>>  1 file changed, 8 insertions(+), 1 deletion(-)
>>>>
>>>> diff --git a/drivers/net/dsa/mv88e6xxx/global1_atu.c b/drivers/net/dsa/mv88e6xxx/global1_atu.c
>>>> index f6cd3c939da4..bac34737b096 100644
>>>> --- a/drivers/net/dsa/mv88e6xxx/global1_atu.c
>>>> +++ b/drivers/net/dsa/mv88e6xxx/global1_atu.c
>>>> @@ -65,7 +65,14 @@ int mv88e6xxx_g1_atu_set_age_time(struct mv88e6xxx_chip *chip,
>>>>  	val &= ~0xff0;
>>>>  	val |= age_time << 4;
>>>>  
>>>> -	return mv88e6xxx_g1_write(chip, GLOBAL_ATU_CONTROL, val);
>>>> +	err = mv88e6xxx_g1_write(chip, GLOBAL_ATU_CONTROL, val);
>>>> +	if (err)
>>>> +		return err;
>>>> +
>>>> +	dev_dbg(chip->dev, "AgeTime set to 0x%02x (%d ms)\n", age_time,
>>>> +		age_time * coeff);
>>>> +
>>>
>>> Hi Vivien
>>>
>>> You could put the dev_dbg before the mv88e6xxx_g1_write(), to keep the
>>> code simpler. If this write fails, we expect a lot of other things to
>>> go horribly wrong, so having one debug message being not quite accurate
>>> is not important.
>>
>> The debug message would not be printed in case mv88e6xxx_g1_write()
>> fails, also, having the message printed after the write occurred is a
>> good way to make sure the write did make it through. Did I miss
>> something in what you are suggesting here?
> 
> We never, ever see a read or a write failure on the MDIO bus. If it
> ever does, i expect the switch is dead, gone, never to be heard from
> again until the power is reset. We are going to have lots of
> failures. So it seems simpler to have:
> 
> 	dev_dbg(chip->dev, "Setting AgeTime to 0x%02x (%d ms)\n", age_time,
> 		age_time * coeff);
> 
> 	return mv88e6xxx_g1_write(chip, GLOBAL_ATU_CONTROL, val);
> 
> and accept that if for some unlikely reason the write does fail, the
> debug message is probably not accurate.
> 
>       Andrew
> 

Hi
The never ever seeing R/W failure on MDIO bus is not exactly accurate.
We had with art (atheros calibration tool) the problem that interrupts
were being disabled which lead to MDIO operations running into
timout/failing.
For normal phys this usually results in calling phy_error in
.../net/phy/phy.c which puts the phy into a defined state (PHY_HALTED).
Granted this is a problem produced by art2 but couldn't the same be
applied here? Put the device in a defined state?

BR
Matthias

[toc] | [prev] | [next] | [standalone]

#1600272

> Hi
> The never ever seeing R/W failure on MDIO bus is not exactly accurate.
> We had with art (atheros calibration tool) the problem that interrupts
> were being disabled which lead to MDIO operations running into
> timout/failing.

Yes, i've seen similar with power management bugs for the MDIO
driver. But you get a cascade of failures, lots of warnings and error
prints, it is clear something bad has happened, and the switch is in
an inconsistent state. So having one more debug print which is also
inconsistent does no really harm.

Anyway, this whole conversation has taken more effort than just making
this simple change to remove a few lines of code. So lets drop it and
move on.

    Andrew

[toc] | [prev] | [next] | [standalone]

#1600443

Hi Andrew,

Andrew Lunn <andrew@lunn.ch> writes:

>> The never ever seeing R/W failure on MDIO bus is not exactly accurate.
>> We had with art (atheros calibration tool) the problem that interrupts
>> were being disabled which lead to MDIO operations running into
>> timout/failing.
>
> Yes, i've seen similar with power management bugs for the MDIO
> driver. But you get a cascade of failures, lots of warnings and error
> prints, it is clear something bad has happened, and the switch is in
> an inconsistent state. So having one more debug print which is also
> inconsistent does no really harm.
>
> Anyway, this whole conversation has taken more effort than just making
> this simple change to remove a few lines of code. So lets drop it and
> move on.

I don't understand nor agree with the fact that sometimes it's OK to not
check for errors, based on one developer assumptions. Not checking
return code is wrong and very likely error-prone.

If you really want to stand for that point, please send a patch series
which turns mv88e6xxx_read() and mv88e6xxx_write() into void functions.
I'd be glad to review and discuss this further. That would indeed make
*all* the driver code simpler.

Thanks,

        Vivien

[toc] | [prev] | [next] | [standalone]

#1600460

On Tue, Mar 14, 2017 at 09:56:41AM -0400, Vivien Didelot wrote:
> Hi Andrew,
> 
> Andrew Lunn <andrew@lunn.ch> writes:
> 
> >> The never ever seeing R/W failure on MDIO bus is not exactly accurate.
> >> We had with art (atheros calibration tool) the problem that interrupts
> >> were being disabled which lead to MDIO operations running into
> >> timout/failing.
> >
> > Yes, i've seen similar with power management bugs for the MDIO
> > driver. But you get a cascade of failures, lots of warnings and error
> > prints, it is clear something bad has happened, and the switch is in
> > an inconsistent state. So having one more debug print which is also
> > inconsistent does no really harm.
> >
> > Anyway, this whole conversation has taken more effort than just making
> > this simple change to remove a few lines of code. So lets drop it and
> > move on.
> 
> I don't understand nor agree with the fact that sometimes it's OK to not
> check for errors, based on one developer assumptions. Not checking
> return code is wrong and very likely error-prone.

Please go back and look what i said. I did check the error code, in
that it gets returned to the caller. I just don't check it before
printing the debug.

But as i said, lets drop this whole topic.

    Andrew

[toc] | [prev] | [standalone]

Back to top | Article view | linux.kernel

csiph-web