Present

Apologies

Actions from previous meeting

Agenda

Actions from this meeting

Activity reports

Colin Watson

Evan Dandrea

James Westby

Lars Wirzenius

Done this week

Remaining from past weeks

Plans for the coming week

Luke Yelavich

Audio

Accessibility

dmraid

Misc

Matthias Klose

Michael Vogt

update-manager

update-notifier

compiz

misc

sponsoring

Scott James Remnant

[1] ehci_hcd supports the USB 2.0 host, which communicates with USB 2.0 devices. uhci_hcd and ohci_hcd support the two different possible USB 1.0/1.1 hosts, which communicate with USB 1.0/1.1 devices. The future xhci_hcd supports the USB 3.0 host, which communicates with USB 3.0 devices (though it may also support the 2.0 host and 2.0 devices). The host is not the ports. If your computer supports both USB 1.0/1.1 and USB 2.0, you will have two USB host controllers:

  1. 00:02.0 USB Controller [0c03]: nVidia Corporation CK804 USB Controller [10de:005a] (rev a2) (prog-if 10)
  2. 00:02.1 USB Controller [0c03]: nVidia Corporation CK804 USB Controller [10de:005b] (rev a3) (prog-if 20)

Note: prog-if 0x00 is uhci_hcd, prog-if 0x10 is ohci_hcd, and prog-if 0x20 is ehci_hcd

These hosts may share the same ports on the computer. This is why the load order matters. In order for USB 2.0 devices to work at full speed, the ehci_hcd driver has to be loaded first to ensure it gets first refusal of them. Since the hosts are separate PCI devices, no one host loads both modules, this is the kind of thing that's very difficult to do in userspace. When we find the USB 1.0/1.1 host, we don't know that there's a 2.0 host yet to come. The USB 2.0 host could be on a PCI card or something that'll be initialised later. The rule basically becomes "always load all three HCD drivers in a set order for any USB host" - and at that point, we may as well just build them into the kernel. So that's what we're doing.

Steve Langasek

Release management

Specs

Packages

Misc

FoundationsTeam/Meetings/2009/0318 (last edited 2009-03-23 17:20:16 by ppp-70-249-34-72)