[PATCH net-next 0/7] net: sfp: improve high power module implementation

[PATCH net-next 0/7] net: sfp: improve high power module implementation

[Russell King (Oracle)]

Hi,

This series aims to improve the power level switching between standard
level 1 and the higher power levels.

The first patch updates the DT binding documentation to include the
minimum and default of 1W, which is the base level that every SFP cage
must support. Hence, it makes sense to document this in the binding.

The second patch enforces a minimum of 1W when parsing the firmware
description, and optimises the code for that case; there's no need to
check for SFF8472 compliance since we will not need to touch the
A2h registers.

Patch 3 validates that the module supports SFF-8472 rev 10.2 before
checking for power level 2 - rev 10.2 is where support for power
levels was introduced, so if the module doesn't support this revision,
it doesn't support power levels. Setting the power level 2 declaration
bit is likely to be spurious.

Patch 4 does the same for power level 3, except this was introduced in
SFF-8472 rev 11.9. The revision code was never updated, so we use the
rev 11.4 to signify this.

Patch 5 cleans up the code - rather than using BIT(0), we now use a
properly named value for the power level select bit.

Patch 6 introduces a read-modify-write helper.

Patch 7 gets rid of the DM7052 hack (which sets a power level
declaration bit but is not compatible with SFF-8472 rev 10.2, and
the module does not implement the A2h I2C address.)

Series tested with my DM7052.

 Documentation/devicetree/bindings/net/sff,sfp.yaml |  2 +
 drivers/net/phy/sfp.c                              | 85 +++++++++++-----------
 include/linux/sfp.h                                |  2 +
 3 files changed, 48 insertions(+), 41 deletions(-)

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
FTTP is here! 40Mbps down 10Mbps up. Decent connectivity at last!

[PATCH net-next 1/7] dt-bindings: net: sff,sfp: update binding

[Russell King (Oracle)]

Add a minimum and default for the maximum-power-milliwatt option;
module power levels were originally up to 1W, so this is the default
and the minimum power level we can have for a functional SFP cage.

Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
---
 Documentation/devicetree/bindings/net/sff,sfp.yaml | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/Documentation/devicetree/bindings/net/sff,sfp.yaml b/Documentation/devicetree/bindings/net/sff,sfp.yaml
index 06c66ab81c01..20d30cccc95e 100644
--- a/Documentation/devicetree/bindings/net/sff,sfp.yaml
+++ b/Documentation/devicetree/bindings/net/sff,sfp.yaml
@@ -23,6 +23,8 @@ title: Small Form Factor (SFF) Committee Small Form-factor Pluggable (SFP)
 
   maximum-power-milliwatt:
     maxItems: 1
+    minimum: 1000
+    default: 1000
     description:
       Maximum module power consumption Specifies the maximum power consumption
       allowable by a module in the slot, in milli-Watts. Presently, modules can
-- 
2.30.2

Re: [PATCH net-next 1/7] dt-bindings: net: sff,sfp: update binding

[Rob Herring]

On Wed, 19 Oct 2022 14:28:46 +0100, Russell King (Oracle) wrote:
> Add a minimum and default for the maximum-power-milliwatt option;
> module power levels were originally up to 1W, so this is the default
> and the minimum power level we can have for a functional SFP cage.
> 
> Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
> ---
>  Documentation/devicetree/bindings/net/sff,sfp.yaml | 2 ++
>  1 file changed, 2 insertions(+)
> 

My bot found errors running 'make DT_CHECKER_FLAGS=-m dt_binding_check'
on your patch (DT_CHECKER_FLAGS is new in v5.13):

yamllint warnings/errors:

dtschema/dtc warnings/errors:
/builds/robherring/dt-review-ci/linux/Documentation/devicetree/bindings/net/sff,sfp.yaml: properties:maximum-power-milliwatt: 'minimum' should not be valid under {'enum': ['const', 'enum', 'exclusiveMaximum', 'exclusiveMinimum', 'minimum', 'maximum', 'multipleOf', 'pattern']}
	hint: Scalar and array keywords cannot be mixed
	from schema $id: http://devicetree.org/meta-schemas/keywords.yaml#

doc reference errors (make refcheckdocs):

See https://patchwork.ozlabs.org/patch/

This check can fail if there are any dependencies. The base for a patch
series is generally the most recent rc1.

If you already ran 'make dt_binding_check' and didn't see the above
error(s), then make sure 'yamllint' is installed and dt-schema is up to
date:

pip3 install dtschema --upgrade

Please check and re-submit.

Re: [PATCH net-next 1/7] dt-bindings: net: sff,sfp: update binding

[Russell King (Oracle)]

On Wed, Oct 19, 2022 at 06:31:53PM -0500, Rob Herring wrote:
> On Wed, 19 Oct 2022 14:28:46 +0100, Russell King (Oracle) wrote:
> > Add a minimum and default for the maximum-power-milliwatt option;
> > module power levels were originally up to 1W, so this is the default
> > and the minimum power level we can have for a functional SFP cage.
> > 
> > Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
> > ---
> >  Documentation/devicetree/bindings/net/sff,sfp.yaml | 2 ++
> >  1 file changed, 2 insertions(+)
> > 
> 
> My bot found errors running 'make DT_CHECKER_FLAGS=-m dt_binding_check'
> on your patch (DT_CHECKER_FLAGS is new in v5.13):
> 
> yamllint warnings/errors:
> 
> dtschema/dtc warnings/errors:
> /builds/robherring/dt-review-ci/linux/Documentation/devicetree/bindings/net/sff,sfp.yaml: properties:maximum-power-milliwatt: 'minimum' should not be valid under {'enum': ['const', 'enum', 'exclusiveMaximum', 'exclusiveMinimum', 'minimum', 'maximum', 'multipleOf', 'pattern']}
> 	hint: Scalar and array keywords cannot be mixed
> 	from schema $id: http://devicetree.org/meta-schemas/keywords.yaml#

I'm reading that error message and it means absolutely nothing to me.
Please can you explain it (and also re-word it to be clearer)?

Thanks.

-- 
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-next 1/7] dt-bindings: net: sff,sfp: update binding

[Rob Herring]

On Thu, Oct 20, 2022 at 09:28:25AM +0100, Russell King (Oracle) wrote:
> On Wed, Oct 19, 2022 at 06:31:53PM -0500, Rob Herring wrote:
> > On Wed, 19 Oct 2022 14:28:46 +0100, Russell King (Oracle) wrote:
> > > Add a minimum and default for the maximum-power-milliwatt option;
> > > module power levels were originally up to 1W, so this is the default
> > > and the minimum power level we can have for a functional SFP cage.
> > > 
> > > Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
> > > ---
> > >  Documentation/devicetree/bindings/net/sff,sfp.yaml | 2 ++
> > >  1 file changed, 2 insertions(+)
> > > 
> > 
> > My bot found errors running 'make DT_CHECKER_FLAGS=-m dt_binding_check'
> > on your patch (DT_CHECKER_FLAGS is new in v5.13):
> > 
> > yamllint warnings/errors:
> > 
> > dtschema/dtc warnings/errors:
> > /builds/robherring/dt-review-ci/linux/Documentation/devicetree/bindings/net/sff,sfp.yaml: properties:maximum-power-milliwatt: 'minimum' should not be valid under {'enum': ['const', 'enum', 'exclusiveMaximum', 'exclusiveMinimum', 'minimum', 'maximum', 'multipleOf', 'pattern']}
> > 	hint: Scalar and array keywords cannot be mixed
> > 	from schema $id: http://devicetree.org/meta-schemas/keywords.yaml#
> 
> I'm reading that error message and it means absolutely nothing to me.
> Please can you explain it (and also re-word it to be clearer)?

'maxItems' is a constraint for arrays. 'maximum' is a constraint for 
scalar values. Mixing them does not make sense.

I have little control over the 1st line as that comes from jsonschema 
package. 'hint' is what I've added to explain things a bit more.

Rob

Re: [PATCH net-next 1/7] dt-bindings: net: sff,sfp: update binding

[Rob Herring]

On Thu, Oct 20, 2022 at 9:19 AM Rob Herring <robh@kernel.org> wrote:
>
> On Thu, Oct 20, 2022 at 09:28:25AM +0100, Russell King (Oracle) wrote:
> > On Wed, Oct 19, 2022 at 06:31:53PM -0500, Rob Herring wrote:
> > > On Wed, 19 Oct 2022 14:28:46 +0100, Russell King (Oracle) wrote:
> > > > Add a minimum and default for the maximum-power-milliwatt option;
> > > > module power levels were originally up to 1W, so this is the default
> > > > and the minimum power level we can have for a functional SFP cage.
> > > >
> > > > Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
> > > > ---
> > > >  Documentation/devicetree/bindings/net/sff,sfp.yaml | 2 ++
> > > >  1 file changed, 2 insertions(+)
> > > >
> > >
> > > My bot found errors running 'make DT_CHECKER_FLAGS=-m dt_binding_check'
> > > on your patch (DT_CHECKER_FLAGS is new in v5.13):
> > >
> > > yamllint warnings/errors:
> > >
> > > dtschema/dtc warnings/errors:
> > > /builds/robherring/dt-review-ci/linux/Documentation/devicetree/bindings/net/sff,sfp.yaml: properties:maximum-power-milliwatt: 'minimum' should not be valid under {'enum': ['const', 'enum', 'exclusiveMaximum', 'exclusiveMinimum', 'minimum', 'maximum', 'multipleOf', 'pattern']}
> > >     hint: Scalar and array keywords cannot be mixed
> > >     from schema $id: http://devicetree.org/meta-schemas/keywords.yaml#
> >
> > I'm reading that error message and it means absolutely nothing to me.
> > Please can you explain it (and also re-word it to be clearer)?
>
> 'maxItems' is a constraint for arrays. 'maximum' is a constraint for
> scalar values. Mixing them does not make sense.

TBC, dropping 'maxItems' is what is needed here.

Rob

Re: [PATCH net-next 1/7] dt-bindings: net: sff,sfp: update binding

[Russell King (Oracle)]

On Thu, Oct 20, 2022 at 09:19:23AM -0500, Rob Herring wrote:
> On Thu, Oct 20, 2022 at 09:28:25AM +0100, Russell King (Oracle) wrote:
> > On Wed, Oct 19, 2022 at 06:31:53PM -0500, Rob Herring wrote:
> > > On Wed, 19 Oct 2022 14:28:46 +0100, Russell King (Oracle) wrote:
> > > > Add a minimum and default for the maximum-power-milliwatt option;
> > > > module power levels were originally up to 1W, so this is the default
> > > > and the minimum power level we can have for a functional SFP cage.
> > > > 
> > > > Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
> > > > ---
> > > >  Documentation/devicetree/bindings/net/sff,sfp.yaml | 2 ++
> > > >  1 file changed, 2 insertions(+)
> > > > 
> > > 
> > > My bot found errors running 'make DT_CHECKER_FLAGS=-m dt_binding_check'
> > > on your patch (DT_CHECKER_FLAGS is new in v5.13):
> > > 
> > > yamllint warnings/errors:
> > > 
> > > dtschema/dtc warnings/errors:
> > > /builds/robherring/dt-review-ci/linux/Documentation/devicetree/bindings/net/sff,sfp.yaml: properties:maximum-power-milliwatt: 'minimum' should not be valid under {'enum': ['const', 'enum', 'exclusiveMaximum', 'exclusiveMinimum', 'minimum', 'maximum', 'multipleOf', 'pattern']}
> > > 	hint: Scalar and array keywords cannot be mixed
> > > 	from schema $id: http://devicetree.org/meta-schemas/keywords.yaml#
> > 
> > I'm reading that error message and it means absolutely nothing to me.
> > Please can you explain it (and also re-word it to be clearer)?
> 
> 'maxItems' is a constraint for arrays. 'maximum' is a constraint for 
> scalar values. Mixing them does not make sense.
> 
> I have little control over the 1st line as that comes from jsonschema 
> package. 'hint' is what I've added to explain things a bit more.

Given that maximum-power-milliwatt is a single value and has never been
an array, it seems then that the original conversion to yaml was wrong.
What should it have been?

(I'm clueless what the difference is between an array and scalar in
this yaml stuff.)

-- 
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-next 1/7] dt-bindings: net: sff,sfp: update binding

[Russell King (Oracle)]

On Thu, Oct 20, 2022 at 09:27:44AM -0500, Rob Herring wrote:
> On Thu, Oct 20, 2022 at 9:19 AM Rob Herring <robh@kernel.org> wrote:
> >
> > On Thu, Oct 20, 2022 at 09:28:25AM +0100, Russell King (Oracle) wrote:
> > > On Wed, Oct 19, 2022 at 06:31:53PM -0500, Rob Herring wrote:
> > > > On Wed, 19 Oct 2022 14:28:46 +0100, Russell King (Oracle) wrote:
> > > > > Add a minimum and default for the maximum-power-milliwatt option;
> > > > > module power levels were originally up to 1W, so this is the default
> > > > > and the minimum power level we can have for a functional SFP cage.
> > > > >
> > > > > Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
> > > > > ---
> > > > >  Documentation/devicetree/bindings/net/sff,sfp.yaml | 2 ++
> > > > >  1 file changed, 2 insertions(+)
> > > > >
> > > >
> > > > My bot found errors running 'make DT_CHECKER_FLAGS=-m dt_binding_check'
> > > > on your patch (DT_CHECKER_FLAGS is new in v5.13):
> > > >
> > > > yamllint warnings/errors:
> > > >
> > > > dtschema/dtc warnings/errors:
> > > > /builds/robherring/dt-review-ci/linux/Documentation/devicetree/bindings/net/sff,sfp.yaml: properties:maximum-power-milliwatt: 'minimum' should not be valid under {'enum': ['const', 'enum', 'exclusiveMaximum', 'exclusiveMinimum', 'minimum', 'maximum', 'multipleOf', 'pattern']}
> > > >     hint: Scalar and array keywords cannot be mixed
> > > >     from schema $id: http://devicetree.org/meta-schemas/keywords.yaml#
> > >
> > > I'm reading that error message and it means absolutely nothing to me.
> > > Please can you explain it (and also re-word it to be clearer)?
> >
> > 'maxItems' is a constraint for arrays. 'maximum' is a constraint for
> > scalar values. Mixing them does not make sense.
> 
> TBC, dropping 'maxItems' is what is needed here.

So how does this work?

maxItems: 1

tells it that there should be an array of one property, which is at the
DT level fundamentally the same as a scalar property.

minimum:
default:
maximum:

tells it that this is a scalar property, so there should be exactly one
item or the property should not be mentioned?

-- 
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-next 1/7] dt-bindings: net: sff,sfp: update binding

[Rob Herring]

On Thu, Oct 20, 2022 at 11:08 AM Russell King (Oracle)
<linux@armlinux.org.uk> wrote:
>
> On Thu, Oct 20, 2022 at 09:27:44AM -0500, Rob Herring wrote:
> > On Thu, Oct 20, 2022 at 9:19 AM Rob Herring <robh@kernel.org> wrote:
> > >
> > > On Thu, Oct 20, 2022 at 09:28:25AM +0100, Russell King (Oracle) wrote:
> > > > On Wed, Oct 19, 2022 at 06:31:53PM -0500, Rob Herring wrote:
> > > > > On Wed, 19 Oct 2022 14:28:46 +0100, Russell King (Oracle) wrote:
> > > > > > Add a minimum and default for the maximum-power-milliwatt option;
> > > > > > module power levels were originally up to 1W, so this is the default
> > > > > > and the minimum power level we can have for a functional SFP cage.
> > > > > >
> > > > > > Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
> > > > > > ---
> > > > > >  Documentation/devicetree/bindings/net/sff,sfp.yaml | 2 ++
> > > > > >  1 file changed, 2 insertions(+)
> > > > > >
> > > > >
> > > > > My bot found errors running 'make DT_CHECKER_FLAGS=-m dt_binding_check'
> > > > > on your patch (DT_CHECKER_FLAGS is new in v5.13):
> > > > >
> > > > > yamllint warnings/errors:
> > > > >
> > > > > dtschema/dtc warnings/errors:
> > > > > /builds/robherring/dt-review-ci/linux/Documentation/devicetree/bindings/net/sff,sfp.yaml: properties:maximum-power-milliwatt: 'minimum' should not be valid under {'enum': ['const', 'enum', 'exclusiveMaximum', 'exclusiveMinimum', 'minimum', 'maximum', 'multipleOf', 'pattern']}
> > > > >     hint: Scalar and array keywords cannot be mixed
> > > > >     from schema $id: http://devicetree.org/meta-schemas/keywords.yaml#
> > > >
> > > > I'm reading that error message and it means absolutely nothing to me.
> > > > Please can you explain it (and also re-word it to be clearer)?
> > >
> > > 'maxItems' is a constraint for arrays. 'maximum' is a constraint for
> > > scalar values. Mixing them does not make sense.
> >
> > TBC, dropping 'maxItems' is what is needed here.
>
> So how does this work?

Do you really want to know? ;)

>
> maxItems: 1

json-schema happily ignores any keywords that it doesn't understand or
don't make sense for a specific context. The DT meta-schema tries to
prevent that.

> tells it that there should be an array of one property, which is at the
> DT level fundamentally the same as a scalar property.

Yes, it is true that the YAML encoded DT and (currently) the internal
encoding used by the tools encode everything as matrices simply
because dtc doing the YAML encoding doesn't know the types beyond what
DTS source level provides, so everything has to be the same encoding.
Now we use the type information in the schemas to decode the DTBs
directly and don't have that limitation. Once I remove the YAML
encoding, we can stop encoding everything as a matrix and having to
fixup the schemas from scalar -> array -> matrix.

> minimum:
> default:
> maximum:
>
> tells it that this is a scalar property, so there should be exactly one
> item or the property should not be mentioned?

Not sure I follow the question. As the property is defined as a
scalar, it only needs scalar keywords. Internally, the schema gets
expanded to:

prop:
  minItems: 1
  maxItems: 1
  items:
    - maxItems: 1
      minItems: 1
      items:
        - maximum: ???
          minimum: ???
          default: ???

This is what processed-schemas.json will contain if you just have the
scalar keywords.

It's a bit more messy now with the unit suffixes as initially they
were all scalars, but over time we've had to allow for arrays. So it's
really they default to scalars unless you need an array in which you
can define:

prop:
  maxItems: 2
  items:
    maximum: ???

Could you do 'maxItems: 1' here? Yes, that would be a valid schema,
but IIRC we'll still complain because it is redundant.

Rob

Re: [PATCH net-next 0/7] net: sfp: improve high power module implementation

[Andrew Lunn]

On Wed, Oct 19, 2022 at 02:28:20PM +0100, Russell King (Oracle) wrote:
> Hi,
> 
> This series aims to improve the power level switching between standard
> level 1 and the higher power levels.
> 
> The first patch updates the DT binding documentation to include the
> minimum and default of 1W, which is the base level that every SFP cage
> must support. Hence, it makes sense to document this in the binding.
> 
> The second patch enforces a minimum of 1W when parsing the firmware
> description, and optimises the code for that case; there's no need to
> check for SFF8472 compliance since we will not need to touch the
> A2h registers.
> 
> Patch 3 validates that the module supports SFF-8472 rev 10.2 before
> checking for power level 2 - rev 10.2 is where support for power
> levels was introduced, so if the module doesn't support this revision,
> it doesn't support power levels. Setting the power level 2 declaration
> bit is likely to be spurious.

Or it is yet another case of violating the standard. The bit is valid,
the revision is wrong in the EEPROM. How long do you think it will be
before we see a quirk like this?

> Patch 4 does the same for power level 3, except this was introduced in
> SFF-8472 rev 11.9. The revision code was never updated, so we use the
> rev 11.4 to signify this.

Great, the standard itself is broken.

       Andrew