[linux-usb-devel] Commit "[PATCH] USB: Always do usb-handoff" breaks my powerbook

[linux-usb-devel] Commit "[PATCH] USB: Always do usb-handoff" breaks my powerbook

Post by Benjamin H » Wed, 02 Nov 2005 11:50:05



Most PCI quirks only do config space accesses


"ppc" doens't do anything fancy that other archs don't do too, please
stop with your "ppc specific" thing all over the place.

It is illegal, whatever the platform is, to tap a PCI device MMIO like
that without calling pci_enable_device(), requesting resources etc... or
at the very least, testing if MMIO decoding is enabled on the chip.
Period. It has nothing to do with PPC and all to do with correctness.


Most quirk only ever use config space. BARs are _not_ guaranteed to be
set at quirk time. In fact, those devices are left disabled on purpose,
thus you should at least test if MMIO access is enabled, and if not,
avoid touching the device at all.


What _That_ code is doing in the quirks... shouldn't it be in the
{U,O,E}HCI drivers instead ?


So you rant about "ppc specific" whatever while the entire point of this
code is to workaround x86 specific BIOS junk ...

Ben.


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[linux-usb-devel] Commit "[PATCH] USB: Always do usb-handoff" breaks my powerbook

Post by Benjamin H » Wed, 02 Nov 2005 12:40:11

n Mon, 2005-10-31 at 19:09 -0800, David Brownell wrote:

The IO accesses probably work fine for some legacy stuff where the ISA
space is actually available, but they are broken if they don't check for
availability, same goes for memory space access.

Damn, those quirks should really be either more careful or be made
platform specific if they are x86 junk workarounds.


Bla bla bla bla... can you stop the crackpipe please ?


I prefer not replying...


Probably. Hopefully, it usually is specifically targeted to chpisets
that often exist only on x86 where they happen to work. Your USB quirk
happen to be broad enough to affect pretty much any platform with USB in
it, and thus the brokenness appears more widely.


More bla bla bla ...


Well, at the _very_ least then read the PCI command register and check
that memory access is enabled before going to your quirk.


Yes, it has, and it properly shuts things down before calling the
operating system, thus doesn't require those "handoff" hacks.

Ben.


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[linux-usb-devel] Commit "[PATCH] USB: Always do usb-handoff" breaks my powerbook

Post by Benjamin H » Wed, 02 Nov 2005 14:20:10


Yup, though I agree that considering the purpose of that code, it might
make sense for it to just "peek" to check if the device was enabled
rather than force-enabling it. If it was not, there is obviously no
handoff to do from the BIOS.

Ben.


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[linux-usb-devel] Commit "[PATCH] USB: Always do usb-handoff" breaks my powerbook

Post by Alan Co » Wed, 02 Nov 2005 18:00:17


USB handoff is fairly x86 specific. The x86 folks took great care to
handle back compatibility while Apple was content to just dump the users
and machines.


Not "illegal" -> "invalid".

Please get that right as we have far too many incorrect uses of
"illegal" in publically visible printk calls. Illegal means "prohibited
by law".


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[linux-usb-devel] Commit "[PATCH] USB: Always do usb-handoff" breaks my powerbook

Post by Benjamin H » Thu, 03 Nov 2005 06:20:17


What is this comment supposed to mean ? Backward compatiblity on Macs is
very high, thanks to mostly software not relying on stupid & broken
hardware implementation details...


Oh well, whatever you say..

Ben.


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