This patch adds skew register settings for KSZ9131. It checks first
which phy is on the board and then applies the correct skew settings.
Skew settings calculation for the KSZ9131:
The i.MX6 SoC has an output skew tolerance of -100ps to 900ps. All
PCB traces where routed exactly the same length so we can calculate
the skew settings without taking the length into consideration. The
traces are all length matched.
RXC skew (PHY to MAC):
- We use the 2ns DLL controlled delay on the PHY
- We do not use the skew registers
This results in the following values:
RXC
PHY fixed Delay 2000ps
PHY Added Delay 0ps
T_setup_R min 2.00ns
T_setup_R typ 2.00ns
T_setup_R max 2.00ns
T_hold_R min 1.60ns
T_hold_R typ 2.00ns
T_hold_R max 2.40ns
That means we are well within RGMII specs.
TXC skew (MAC to PHY):
- We use the 2ns DLL controlled delay on the PHY
- We then subtract ~0.6ns with TXD[0:3] and TXC clock pad skew
register in a resulting ~1.4ns delay.
This results in the following values under consideration of the
tolerances:
TXC min TXC typ TXC max
MAC min -100ps -100ps -100ps
MAC max 900ps 900ps 900ps
PHY fixed Delay 2000ps 2000ps 2000ps
PHY added Delay -340ps -600ps -859ps
T_setup_T min 1.56ns 1.30ns 1.04ns
T_setup_T typ 2.06ns 1.80ns 1.54ns
T_setup_T max 2.56ns 2.30ns 2.04ns
T_hold_T min 1.04ns 1.30ns 1.56ns
T_hold_T typ 1.94ns 2.20ns 2.46ns
T_hold_T max 2.84ns 3.10ns 3.36ns
This shows that T_hold_T min and T_setup_T min times are out of spec
for RGMII timing. However the KSZ9131 has a minimal value for this time
of 0.8ns which is met under all circumstances.
Signed-off-by: Philippe Schenker <philippe.schenker@toradex.com>
Like [1], reset the FLP burst timing for the KSZ9031 to the 16ms
specified by the IEEE802.3 standard from the chip's default of 8ms.
For more details, see the "Auto-Negotiation Timing" section of the
KSZ9031RNX datasheet.
[1] https://patchwork.kernel.org/patch/6558371/
Signed-off-by: Ash Charles <ash.charles@savoirfairelinux.com>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>
cgtqmx6eval can be populated with a AR8035 or KSZ9031 depending on the
board revision.
Add Ethernet support.
Signed-off-by: Otavio Salvador <otavio@ossystems.com.br>
Add the gigabit phy KSZ9021.
Also, add function ksz9021_phy_extended_write
/_read for access to the phys extended registers.
The environment variable "disable_giga"
can be used to disable 1000baseTx.
Signed-off-by: Troy Kisky <troy.kisky@boundarydevices.com>
Acked-by: Dirk Behme <dirk.behme@de.bosch.com>
Philippe Schenker