Hi Russell, On Tue, May 08, 2018 at 01:30:26PM +0100, Russell King - ARM Linux wrote: > > The electronic engineer in me says that using zero isn't really valid > because there are coupling capacitors in the SFP module that block DC. > These blocking capacitors are required by the SFP+ specs to have a high > pass pole of between 20kHz and 100kHz - in other words, frequencies > below this are attenuated by the coupling capacitors. The relationship > between this and the bit rate will be a function of the encoding, so we > can't come to a definitive figure without some math (and I want to be > lazy about that!) > > Practically, we're talking about SerDes Ethernet, where the bit rate is > no lower than 100Mbps [*], which will always have a frequency well above > this cut-off. So, I don't have any problem with your approach to > setting the minimum to zero. Therefore, > > Acked-by: Russell King <rmk+ker...@armlinux.org.uk>
Thanks for looking into it! Antoine -- Antoine Ténart, Bootlin (formerly Free Electrons) Embedded Linux and Kernel engineering https://bootlin.com
