> -----Original Message----- > From: Stephen Warren [mailto:swar...@wwwdotorg.org] > Sent: Thursday, June 28, 2012 12:58 AM > To: Wolfgang Denk> > Cc: Jim Lin; 'U-Boot@lists.denx.de'; Tom Warren > Subject: Re: [U-Boot] [PATCH 1/1] USB: EHCI: Initialize multiple USB > controllers at once
> > On 06/27/2012 12:55 AM, Wolfgang Denk wrote: > > Dear Jim Lin, > > > > sending the very same message eight (8!) times doesnot make it a bit > > more convincing - on contrary. > > > > In message <4b9c9637d5087840a465bdcb251780e9e2d6eda...@hkmail02.nvidia.com> > > you wrote: > >> > >>> U-Boot is not multi-tasking, so you can always access only a single > >>> USB device at a time ayway. And it is a decoumented design principle > >>> that U-Boot must not initialize any devices it does not use itself.> > >>> > >>> So why? > >> Because of this complaint and request for devices under different > >> controllers > >> to be working at same time. > > > > You make another claim here, but don't explain how this is supposed to > > work or whay the exact use case would be where this was needed. > > U-Boot will not be able to access multiple devices at the same time, > > so why would it be necessary to enable these? It should be sufficient > > to enable the controller that is responsible for the single device > > that is currently being used. > > > >> "One particularly annoying consequence of this is when you use the Seaboard > >> configuration on Springbank. > >> Seaboard selects Tegra's USB3 as "usb 0" device, which is the one you can > >> use, > >> in order not to conflict with the flashing USB port USB1. > >> However, Springbank only exposes USB1 since USB3 is used internally for the > >> USB keyboard/mouse. As such, you cannot use the USB port on Springbank > >> under > >> U-Boot at the moment. > >> " > > > > I have to admit that I cannot make any sense from this statement. The > > only thing I understand is that you are trying to use a configuration > > for one hardware (Seaboard) on another, incompatible hardware > > (Springbank). > > > > The simple answer to this problem is: don't do that, then. > Seaboard and Springbank are essentially the same board, and hence are > almost 100% SW compatible, so there's no problem running a Seaboard > build of U-Boot/kernel/... on Springbank. > The primary issue here is that many boards have multiple USB ports. > Users could plug e.g. a USB->Ethernet device into any of the ports. > Requiring the user to know which port is which ID so they can issue the > correct "usb start <n>" command is painful; no other SW stack limits > itself to a single port and so most people don't have a clue which ports > are numbered what; they just want USB to work. > The specific issue on Springbank is that there are multiple USB ports > that are useful at the essentially the same time. One of the USB ports > hosts a built-in USB keyboard (inside a sealed clamshell/netbook case), > which we would like to use for the U-boot console. Another USB port is > external, and people will plug in a USB->Ethernet dongle or USB storage > device there. so, if I need to "usb start 0" to get the keyboard, and > "usb start 1" to get USB Ethernet, then as soon as I "usb start 1" to > get the Ethernet, I've just lost the console, and am unable to interact > with U-Boot any more.. Wolfgang, Any further thought about Stephen's request? Thanks. nvpublic _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot