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Re: [Patch] [bug #26237] multiple problems with usb devices

From: Aleš Nesrsta
Subject: Re: [Patch] [bug #26237] multiple problems with usb devices
Date: Sun, 23 May 2010 19:42:19 +0200

Vladimir 'φ-coder/phcoder' wrote:

> >  It could make troubles on SCSI subclass
> > devices but I tried all my devices with SCSI subclass with
> > ATAPI-compatible length of command and all devices are working normally
> > - so I think it should be safe to use ATAPI format of commands
> > universally for any subclass and I tried to "add support" for most of
> > USB MS subclasses - in fact I only extended one condition in usbms.c...
> > I did not testing devices subclasses RBC, UFI and MMC-2 - I don't have
> > such devices - can do somebody such tests ?
> >   
> Is MMC-2 subclass of cardreaders?

I think probably not.
Full description of subcalss is "SFF-8020i, MMC-2 (ATAPI)" and comment
is that such subclass is used mainly by CD/DVD.

For example here is written:
"If you are looking for the SCSI command set used by ATAPI CD-ROM or DVD
devices then you should go to the T10 site and find the MMC or MMC-2
documents. Please note that the old SFF-8020 (INF-8020) document is now
obsolete. SFF-8020 (INF-8020) has been replaced by the T13 ATA/ATAPI-4
standard (for the interface and command protocol descriptions) and by
the T10 MMC or MMC-2 standards (for the SCSI command set).
The SCSI standards are published by ANSI NCITS Technical Committee 10,
or just T10: T10 - Technical Committee 10  "

Unfortunately you should be a member of T10 to get access to many
documents, MMC-2 is one of them...

But there is free access for example to some implementation notes on

> > Unfortunately, I probably cannot help You as I don't have GEODE or
> > Yeeloong... I can hope only that my corrections would help You or
> > inspire You in some other ways.
> >   
> I don't think it's something deeply specific to Geode. Other than having
> Geode MSR instead of PCI configuration space it's normal OHCI. Actually
> with your patch when you forgot to power device up it resulted in
> similar symptoms on PCI OHCI controller. OHCI specification mentions
> different ways to configure power settings. I guess geode defaults to
> another mode than most controllers do. Or perhaps I need to somehow
> enable ports.
> >

OHCI specification is little bit unclear in the case of root hub port
registers - some values are there marked "Implementation Specific" and
there is not clear for me if any OHCI HC must support any combination of
powering or not.

Best regards

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