Thread (12 messages) 12 messages, 3 authors, 2018-08-27

Re: [PATCH 1/3] ARM: dts: NSP: Enable SFP on bcm958625hr

From: Russell King - ARM Linux <linux@armlinux.org.uk>
Date: 2018-08-27 22:27:11
Also in: linux-arm-kernel, lkml

On Mon, Aug 27, 2018 at 01:03:42PM -0700, Florian Fainelli wrote:
Enable the SFP connected to port 5 of the switch and wire up all GPIOs
to the SFP cage. Because of a hardware limitation of the i2c controller
on the iProc SoCs which prevents large i2c (> 256 bytes) transactions to
work, we use the i2c-gpio interface instead, which does not have that
limitation. This allows us to read the SFP module EEPROM, which would
not be possible otherwise since it exceeds that size during a single
read transfer.
We shouldn't exceed 256 bytes, since 256 bytes is the "page" size
of the EEPROM.  The most that we read in one block is either
ETH_MODULE_SFF_8079_LEN or (ETH_MODULE_SFF_8472_LEN - 
ETH_MODULE_SFF_8079_LEN), both of which result in no more than 256
byte reads.

-- 
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