Re: [PATCH v5 net-next] net: phy: Add Edge-rate driver for Microsemi PHYs.

[Raju Lakkaraju]

Hi Andrew,

Thank you for comments. I will fix and send the patch.

Thanks,
Raju.

On Tue, Oct 04, 2016 at 08:54:01AM +0200, Andrew Lunn wrote:
> EXTERNAL EMAIL
> 
> 
> On Tue, Oct 04, 2016 at 12:48:59AM -0400, David Miller wrote:
> > From: Raju Lakkaraju 
> > Date: Mon, 3 Oct 2016 12:53:13 +0530
> >
> > > From: Raju Lakkaraju 
> > >
> > > Edge-rate:
> > > As system and networking speeds increase, a signal's output transition,
> > > also know as the edge rate or slew rate (V/ns), takes on greater 
> > > importance
> > > because high-speed signals come with a price. That price is an assortment 
> > > of
> > > interference problems like ringing on the line, signal overshoot and
> > > undershoot, extended signal settling times, crosstalk noise, transmission
> > > line reflections, false signal detection by the receiving device and
> > > electromagnetic interference (EMI) -- all of which can negate the 
> > > potential
> > > gains designers are seeking when they try to increase system speeds 
> > > through
> > > the use of higher performance logic devices. The fact is, faster signaling
> > > edge rates can cause a higher level of electrical noise or other type of
> > > interference that can actually lead to slower line speeds and lower 
> > > maximum
> > > system frequencies. This parameter allow the board designers to change the
> > > driving strange, and thereby change the EMI behavioral.
> > >
> > > Edge-rate parameters (vddmac, edge-slowdown) get from Device Tree.
> > >
> > > Tested on Beaglebone Black with VSC 8531 PHY.
> > >
> > > Signed-off-by: Raju Lakkaraju 
> >
> > Applied, thanks.
> 
> Oh dear. It was not ready for acceptance yet. I guess you missed all
> the discussion because it was attached to the previous version of the
> patch.
> 
> Raju you now need to submit fixup patches relative to the version
> David has accepted, to fix the issues we were discussing.
> 

Accepted.

>   Andrew
> 

Re: [PATCH v5 net-next] net: phy: Add Edge-rate driver for Microsemi PHYs.

[Andrew Lunn]

On Tue, Oct 04, 2016 at 03:01:34AM -0400, David Miller wrote:
> From: Andrew Lunn 
> Date: Tue, 4 Oct 2016 08:54:01 +0200
> 
> > Oh dear. It was not ready for acceptance yet. I guess you missed all
> > the discussion because it was attached to the previous version of the
> > patch.
> > 
> > Raju you now need to submit fixup patches relative to the version
> > David has accepted, to fix the issues we were discussing.
> 
> My bad, I'm trying to queue everything up for the merge window
> pull request.

Hi David

We should be able to get fixups done quickly. The binding concept is
now hashed out, unless it takes another unexpected twist and turn.  So
even if we miss the pull request, the fixup should be ready for when
-rc1 comes out.

 Andrew

Re: [PATCH v5 net-next] net: phy: Add Edge-rate driver for Microsemi PHYs.

[David Miller]

From: Andrew Lunn 
Date: Tue, 4 Oct 2016 08:54:01 +0200

> Oh dear. It was not ready for acceptance yet. I guess you missed all
> the discussion because it was attached to the previous version of the
> patch.
> 
> Raju you now need to submit fixup patches relative to the version
> David has accepted, to fix the issues we were discussing.

My bad, I'm trying to queue everything up for the merge window
pull request.

Re: [PATCH v5 net-next] net: phy: Add Edge-rate driver for Microsemi PHYs.

[Andrew Lunn]

On Tue, Oct 04, 2016 at 12:48:59AM -0400, David Miller wrote:
> From: Raju Lakkaraju 
> Date: Mon, 3 Oct 2016 12:53:13 +0530
> 
> > From: Raju Lakkaraju 
> > 
> > Edge-rate:
> > As system and networking speeds increase, a signal's output transition,
> > also know as the edge rate or slew rate (V/ns), takes on greater importance
> > because high-speed signals come with a price. That price is an assortment of
> > interference problems like ringing on the line, signal overshoot and
> > undershoot, extended signal settling times, crosstalk noise, transmission
> > line reflections, false signal detection by the receiving device and
> > electromagnetic interference (EMI) -- all of which can negate the potential
> > gains designers are seeking when they try to increase system speeds through
> > the use of higher performance logic devices. The fact is, faster signaling
> > edge rates can cause a higher level of electrical noise or other type of
> > interference that can actually lead to slower line speeds and lower maximum
> > system frequencies. This parameter allow the board designers to change the
> > driving strange, and thereby change the EMI behavioral.
> > 
> > Edge-rate parameters (vddmac, edge-slowdown) get from Device Tree.
> > 
> > Tested on Beaglebone Black with VSC 8531 PHY.
> > 
> > Signed-off-by: Raju Lakkaraju 
> 
> Applied, thanks.

Oh dear. It was not ready for acceptance yet. I guess you missed all
the discussion because it was attached to the previous version of the
patch.

Raju you now need to submit fixup patches relative to the version
David has accepted, to fix the issues we were discussing.

  Andrew

Re: [PATCH v5 net-next] net: phy: Add Edge-rate driver for Microsemi PHYs.

[David Miller]

From: Raju Lakkaraju 
Date: Mon, 3 Oct 2016 12:53:13 +0530

> From: Raju Lakkaraju 
> 
> Edge-rate:
> As system and networking speeds increase, a signal's output transition,
> also know as the edge rate or slew rate (V/ns), takes on greater importance
> because high-speed signals come with a price. That price is an assortment of
> interference problems like ringing on the line, signal overshoot and
> undershoot, extended signal settling times, crosstalk noise, transmission
> line reflections, false signal detection by the receiving device and
> electromagnetic interference (EMI) -- all of which can negate the potential
> gains designers are seeking when they try to increase system speeds through
> the use of higher performance logic devices. The fact is, faster signaling
> edge rates can cause a higher level of electrical noise or other type of
> interference that can actually lead to slower line speeds and lower maximum
> system frequencies. This parameter allow the board designers to change the
> driving strange, and thereby change the EMI behavioral.
> 
> Edge-rate parameters (vddmac, edge-slowdown) get from Device Tree.
> 
> Tested on Beaglebone Black with VSC 8531 PHY.
> 
> Signed-off-by: Raju Lakkaraju 

Applied, thanks.

[PATCH v5 net-next] net: phy: Add Edge-rate driver for Microsemi PHYs.

[Raju Lakkaraju]

From: Raju Lakkaraju 

Edge-rate:
As system and networking speeds increase, a signal's output transition,
also know as the edge rate or slew rate (V/ns), takes on greater importance
because high-speed signals come with a price. That price is an assortment of
interference problems like ringing on the line, signal overshoot and
undershoot, extended signal settling times, crosstalk noise, transmission
line reflections, false signal detection by the receiving device and
electromagnetic interference (EMI) -- all of which can negate the potential
gains designers are seeking when they try to increase system speeds through
the use of higher performance logic devices. The fact is, faster signaling
edge rates can cause a higher level of electrical noise or other type of
interference that can actually lead to slower line speeds and lower maximum
system frequencies. This parameter allow the board designers to change the
driving strange, and thereby change the EMI behavioral.

Edge-rate parameters (vddmac, edge-slowdown) get from Device Tree.

Tested on Beaglebone Black with VSC 8531 PHY.

Signed-off-by: Raju Lakkaraju 

---
All the review comments updated and resending for review.

Change set:
v1:
- Initial version of Edge-rate driver add by using IOCTL.
v2:
- Changed edge-rate parameter to Device Tree with magic number.
v3:
- Added Device Tree documentati0n and edge-rate parameter table.
  Added probe function initialize the vsc8531 private data structure.
v4:
- As per review comment, Device Tree parameters (vddmac, edge-slowdown)
  added.
v5:
- As per review comment, Device Tree Document parameters (vddmac, 
  edge-slowdown) real numbers added. Table number changed from 5 to 1.

---

 .../devicetree/bindings/net/mscc-phy-vsc8531.txt   |  58 ++
 drivers/net/phy/mscc.c | 125 +
 include/dt-bindings/net/mscc-phy-vsc8531.h |  21 
 3 files changed, 204 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/net/mscc-phy-vsc8531.txt
 create mode 100644 include/dt-bindings/net/mscc-phy-vsc8531.h

diff --git a/Documentation/devicetree/bindings/net/mscc-phy-vsc8531.txt 
b/Documentation/devicetree/bindings/net/mscc-phy-vsc8531.txt
new file mode 100644
index 000..99c7eb0
--- /dev/null
+++ b/Documentation/devicetree/bindings/net/mscc-phy-vsc8531.txt
@@ -0,0 +1,58 @@
+* Microsemi - vsc8531 Giga bit ethernet phy
+
+Required properties:
+- compatible   : Should contain phy id as "ethernet-phy-id."
+ The PHY device uses the binding described in
+ Documentation/devicetree/bindings/net/phy.txt
+
+Optional properties:
+- vsc8531,vddmac   : The vddmac in mV.
+- vsc8531,edge-slowdown: % the edge should be slowed down relative to
+ the fastest possible edge time. Native sign
+ need not enter.
+ Edge rate sets the drive strength of the MAC
+ interface output signals.  Changing the drive
+ strength will affect the edge rate of the output
+ signal.  The goal of this setting is to help
+ reduce electrical emission (EMI) by being able
+ to reprogram drive strength and in effect slow
+ down the edge rate if desired.  Table 1 shows the
+ impact to the edge rate per VDDMAC supply for each
+ drive strength setting.
+ Ref: Table:1 - Edge rate change below.
+
+Note: see dt-bindings/net/mscc-phy-vsc8531.h for applicable values
+
+Table: 1 - Edge rate change
+|
+|  Edge Rate Change (VDDMAC)   |
+|  |
+| 3300 mV  2500 mV 1800 mV 1500 mV |
+|---|
+| Default  Deafult Default Default |
+| (Fastest)(recommended)   (recommended)   |
+|---|
+| -2%  -3% -5% -6% |
+|---|
+| -4%  -6% -9% -14%|
+|---|
+| -7%  -10%-16%-21%|
+|(recommended) (recommended)   |
+|---|
+| -10% -14%-23%-29%|
+|---|
+| -17% -23%-35%-42%|