Re: [PATCH v8 net-next] net: phy: Add Edge-rate driver for Microsemi PHYs.

On Wed, Oct 05, 2016 at 05:09:38PM +0530, Raju Lakkaraju wrote:

From: Raju Lakkaraju <Raju.Lakkaraju-dzo6w/eZyo2tG0bUXCXiUA@public.gmane.org>

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 <Raju.Lakkaraju-dzo6w/eZyo2tG0bUXCXiUA@public.gmane.org>

---
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.
v6:
- As per review comment, Removed Device Tree header file. Removed MACROs
  and add ARRAYSIZE
v7:
- As per review comment, Removed '-'s (minus) sign in Edge rate table. 
v8:
- As per review comment, Added DT vddmac, slowdown value error check. 

---

 .../devicetree/bindings/net/mscc-phy-vsc8531.txt   | 22 +++----

Acked-by: Rob Herring <redacted>

 drivers/net/phy/mscc.c                             | 69 +++++++++++++++-------
 include/dt-bindings/net/mscc-phy-vsc8531.h         | 21 -------
 3 files changed, 59 insertions(+), 53 deletions(-)
 delete mode 100644 include/dt-bindings/net/mscc-phy-vsc8531.h

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