Hi Nikolay, (jumping a little later in the discussion but trying to sumarize all topics..)
IMHO we should find a way without constraining SPL to work differently as thought only to allow loading from USB. For this reason I will tend to a solution as much as possible "tools" only, that is extending imx-usb-loader as try to bind together SPL and u-boot.bin and convince SPL to load from memory. This becomes an artifact, because in the reality, SPL loads from a storage. On 01/06/2015 01:15, Nikolay Dimitrov wrote: > Hi guys, > > Here's a proposal how to avoid changing the host boot software for the > SPL case: > > - Power on > - Boot ROM announces usb device (0x15a2:0x0054 or 0x15a2:0x0054 or > 0x15a2:0x0063) > - Host software uploads SPL over OTG > - Board initializes DDR > - Board initializes USB-OTG and announces again as a usb device with > slightly different PID (0x15a2:0x0055 or 0x15a2:0x0056 or > 0x15a2:0x0064) or a special PID (0x15a2:0xffff), thus needs to > implement FSL boot protocol It looks like a straightforward solution. I guess that the USB-OTG initialization is done as fallback when SPL cannot load from storage, allowing us to have a single binary for "standard" booting and USB booting. When load fails, USB is initialized. > - Both imx-usb-loader and mfgtool already have easy mechanism to detect > boards' by vid-pid and to sequence actions based on it. So basically > we'll just need an additional config for the host boot programs, which > need to feed the 2nd boot stage (one more file for imx-usb-loader, and > one more config section for the mfgtool), but otherwise it will be > quite straight-forward. Agree, this looks like a straight-forward solution. > > Overall, from the PC host this boot sequence will look like 2 boot > sequences for 2 separate usb devices (1 for SPL, 1 for u-boot.img). > > Probably the most important question is "how easy is to implement the > FSL boot protocol in the remaining OCRAM free space". What do you think? > Best regards, Stefano Babic -- ===================================================================== DENX Software Engineering GmbH, Managing Director: Wolfgang Denk HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany Phone: +49-8142-66989-53 Fax: +49-8142-66989-80 Email: sba...@denx.de ===================================================================== _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot