[U-Boot] Make "usb start" only start / scan usb once ?

[Marek Vasut <marex@denx.de>]

On Wednesday, November 26, 2014 at 01:44:23 PM, Hans de Goede wrote:
> Hi,

Hello Hans,

> Currently we've this magic in include/config_distro_bootcmd.h to avoid
> scanning the usb bus multiple times.
> 
> And it does not work when also using an usb keyboard because then the
> preboot command has already scanned the bus, so we're still scanning it
> twice.
> 
> While discussing my latest attempt at fixing this:
> 
> http://patchwork.ozlabs.org/patch/413394/
> http://patchwork.ozlabs.org/patch/413395/
> 
> With Ian, Ian said why not simply make "usb start" keep track of if it
> already has started things, and then we can remove all the magic for it
> from include/config_distro_bootcmd.h and just call it unconditionally.
> 
> This would also cause "usb start" and "usb reset" to actually do something
> different, where as currently they are 100% the same.
> 
> I must say I like this idea, the only downside is, that it could be seen
> as a break of the u-boot cmdline API, one could easily argue it is not,
> because usb will be started by "usb start" if necessary, and people can
> still force a rescan with "usb reset".
> 
> So any input on this, specifically would a patch-set to make "usb start"
> start usb only once (per boot) be acceptable ?

It just makes a lot of sense, so yes. You're right it'd break the command
like API and it might be a surprise to some, but you're also right that the
current "way of things" is confusing and possibly even wrong.

Apologies I got back to you so late.

Best regards,
Marek Vasut