From mboxrd@z Thu Jan 1 00:00:00 1970 From: Vince Bridgers Date: Fri, 13 Feb 2015 16:05:43 +0000 Subject: [U-Boot] [PATCH 2/2] net: phy: Add ability to program the ksz9031 skew values from the uboot env In-Reply-To: <54DAFFF6.20003@denx.de> References: <1423493073-9462-1-git-send-email-vbridger@opensource.altera.com> <201502092018.52128.marex@denx.de> <1423517501329.58727@opensource.altera.com> <201502101951.35515.marex@denx.de>,<54DAFFF6.20003@denx.de> Message-ID: <1423843542741.14514@opensource.altera.com> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de Hi Stefan > > > > Setting the skews in DT would indeed be preferable in my opinion. > +1 from me. Agreed. I'll focus on a devicetree based implementation, and editing phy values during board debug and bringup can be addressed with debug/development notes. I'd be willing to publish these somewhere with some suggestions about the best place for something like this to reside based on our experience. > > > > You can do that with the 'mii' command as well I think, but I might be wrong. > Yes. For testing or board bringup this might really serve. Even though > this setting via environment as proposed from Vince is more elegant and > less hackish. And easier to adjust/tune for "normal users". This was the intent of having environment variables - to make trying different skew values easy for our customers. Not all developers/users are Uboot experts and need help from time to time. I think this can also be addressed by writing use case notes on how to edit phy registers using the mii command for debug/bringup purposes. > The default values should come from the DT, once this is all in place. > But I think that for initial board bringup / testing such a method, to > override those values via environment variables can be quite helpful. After reading through most of the comments, I agree with Marek it's possible (and probably best) to support overriding phy registers through use of the mii command. Non expert users (such as hardware developers bringing up a new board) could make use of notes to help them know how to try different settings. All the best! Vince