USB Attached SCSI (UAS/UASP) support and fallback to BOT

[Hans Petter Selasky]

On 11/22/17 09:22, rdj at brazilmail.com wrote:
> Has support for UAS/UASP (ASMedia 115x chipsets etc.) been
> added to FreeBSD (following Lev Serebryakov's post in Nov 2016)?
> 
> Can someone with a UAS/UASP HDD enclosure (docking station)
> report on what happens when it's connected... does it fall back
> to operating in BOT (Bulk Only Transport) mode as a UMASS
> device?
>

Hi,

There is no UAS support in FreeBSD. The feature is controversial in USB 
circles, due to the dependency of a special and new USB 3.0 endpoint 
mode, called STREAMs mode. Not all USB host controllers support it. In 
FreeBSD STREAMs mode is disabled by default.

In USB 2.0 mode the device will fallback to UMASS.

In USB 3.0 it is vendor dependent if there is any fallback mode.

--HPS