[PATCH 1/1] uboot-pcf50633-default-curr-lim-1A.patch

Harald Welte laforge at openmoko.org
Wed Feb 20 17:27:28 CET 2008

On Wed, Feb 20, 2008 at 02:46:32PM +0800, Andy Green wrote:

> uboot-pcf50633-default-curr-lim-1A.patch
> From: Andy Green <andy at openmoko.com>
> 1) Stop PMU killing us if we don't have a battery in (by setting default
>     current limit to 1A)

Sorry, but:

This has to have a BIG FAT warning and it needs to be absolutely sure
that this code is _never_ put onto any production / 'sold' devices.  You
cannot draw more than 100mA from USB without being configured by the
host.  Even in the latter case, you can only draw up to 500mA, since
this is the maximum current requirement that your config descriptor can

This clearly violates the USB spec and thus is sufficient grounds for
anyone to claim the product is not USB compliant.

Yes, I know there are other products, particularly from shady small
noname manufacturers in the far east that do the same.  Nonetheless, it
is probably not the best idea to follow in their footsteps.

Yes, there actually are USB ports that don't supply more than 100mA.
Among them are all bus-powered hubs, many OTG devices and small handheld
devices with USB host.

- Harald Welte <laforge at openmoko.org>          	        http://openmoko.org/
Software for the world's first truly open Free Software mobile phone

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