On Wed, 24 Mar 2021 09:55:04 +0000 Kostya Porotchkin <kos...@marvell.com> wrote:
> Hi, Marek, > > > -----Original Message----- > > From: Marek Behun <marek.be...@nic.cz> > > Sent: Wednesday, March 24, 2021 12:44 > > To: Stefan Roese <s...@denx.de> > > Cc: u-boot@lists.denx.de; Kostya Porotchkin <kos...@marvell.com>; Stefan > > Chulski <stef...@marvell.com>; Ramon Fried <rfried....@gmail.com>; > > Nadav Haklai <nad...@marvell.com>; Joe Hershberger > > <joe.hershber...@ni.com>; Marcin Wojtas <m...@semihalf.com>; sa_ip-sw- > > jenkins <sa_ip-sw-jenk...@marvell.com>; Igal Liberman <ig...@marvell.com>; > > Simon Glass <s...@chromium.org>; Yan Markman <ymark...@marvell.com> > > Subject: [EXT] Re: [PATCH v1 2/5] net: phy: marvell: extend 88E2110 to use > > both 2.5GHz modes > > > > External Email > > > > ---------------------------------------------------------------------- > > On Wed, 24 Mar 2021 10:20:05 +0100 > > Stefan Roese <s...@denx.de> wrote: > > > > > PHY_INTERFACE_MODE_SGMII_2500 > > > > What the hell is this mode??? > > > > AFAIK something like this does not actually exist. > [KP] I think you are wrong. These modes are definitely exist > https://en.wikipedia.org/wiki/2.5GBASE-T_and_5GBASE-T > > Regards > Kosta Hi Kosta, the wikipedia page you linked specifies copper modes, not PHY modes. We are discussing PHY modes here. What I am confused about is that this patch adds check for PHY_INTERFACE_MODE_SGMII_2500 in addition to PHY_INTERFACE_MODE_2500BASEX But what is the difference between these two? Marvell named this protocol HS-SGMII in some of their datasheets and code. I guess this was done because of the similarities with 1000base-x and SGMII. Marvell uses the names SGMII and 1000base-x interchangably, although this is not correct. I guess they are similarily using names 2500base-x and HS-SGMII (and now SGMII_2500) interchangably, which is also not correct. SGMII uses the same coding as 1000base-x, but the latter works only with one speed (1000mbps), while the former can also work in 10mbps and 100mbps (by repeating each byte 100 or 10 times, respectively). Then there is 2500base-x, which is the same as 1000base-x, but with the clock being at 2.5x the speed of 1000base-x clock. But there is no analogue of the SGMII protocol (i.e. the repearing of bytes in order to achieve lower speed) for the 2500base-x. So what I am confused about here is what is supposed to be the difference between PHY_INTERFACE_MODE_SGMII_2500 and PHY_INTERFACE_MODE_2500BASEX ? Marek
