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Linux 2.4.5-ac7

DISCUSSION Pete Zaitcev 3 participants 3 messages Jun 3, 2001 – Jun 5, 2001 1 message not in the archive

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#1 lore raw
Quoted 7 lines

AC> 2.4.5-ac7
AC> o Make USB require PCI (me)

How about people from StrongArm sa11x0 port, who have USB host controller (in sa1111 companion chip) but do not have PCI?
Probably there are more such embedded architectures with USB controllers, but not PCI bus.

There is nothing that would bind USB to PCI architecturally. OHCI and UHCI are PCI based, but that's just a matter of implementation. I think that Alan was unwise at this point.

I know that some small Motorola parts (relatives of 860, perhaps) do have USB controllers, but I have no idea if PCI is involved.

Quoted 1 line

How about ISA USB host controllers?

Those, unfortunately, do not exist. I was shopping for one in vain for a long time. One formiddable difficulty is that USB bandwidth is larger than ISA, so the only feasible way to make a HC is to have all TD's in its onboard memory, as in VGA.

In other follow-up Alan argued in favor of CONFIG_PCI for a PCI-less machine. It may be a reasonable approach, for instance JavaStation-1 has no PCI but requires CONFIG_PCI. It adds a little of useless bloat, that I considered a necessary evil in the abovementioned case.

-- Pete

#2 lore raw
In reply to a message not in the archive

Hi!

Quoted 7 lines
Quoted 1 line

How about ISA USB host controllers?

Those, unfortunately, do not exist. I was shopping for one in vain for a long time. One formiddable difficulty is that USB bandwidth is larger than ISA, so the only feasible way to make a HC is to have all TD's in its onboard memory, as in VGA.

USB is 1.2MB/sec while 8-bit ISA is 4MB/sec (memory-mapped).

...and OHCI does use board memory, anyway.
Pavel

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#3 lore raw
In reply to a message not in the archive
Quoted 10 lines · Pavel Machek

Hi!

Quoted 7 lines
Quoted 1 line

How about ISA USB host controllers?

Those, unfortunately, do not exist. I was shopping for one in vain for a long time. One formiddable difficulty is that USB bandwidth is larger than ISA, so the only feasible way to make a HC is to have all TD's in its onboard memory, as in VGA.

Quoted 3 lines

USB is 1.2MB/sec while 8-bit ISA is 4MB/sec (memory-mapped).

...and OHCI does use board memory, anyway.

And strangely enough a couple of vendors offer USB-to-ISA bridges:
passive ISA backplanes that you can connect to your system using USB. Just search for "USB ISA" with google.com ...

Dominik

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