Re: [Sdhci-devel] SDHCI driver runnining in aspire one, allows towrite to R/O SD cards
From: Garrett D'Amore
Date: Mon Apr 27 2009 - 18:20:00 EST
Maxim Levitsky wrote:
On Mon, 2009-04-27 at 11:12 -0700, Garrett D'Amore wrote:
As an extra data point, my sdhost driver in OpenSolaris works fine on
the AA1.. it does see that the cards are locked, and refuses to allow
them to be mounted read/write.
This leads me to believe that the original linux problem is one of two
things:
* either a bug in the linux code, or
* busted circuit/hardware on a specific unit (i.e. a damaged unit)
I believe that if the Linux code was buggy here, the problem would be
reproducible on all platforms, not just the AA1. So my inclination,
barring independent confirmation, is that most likely there are one ore
more defective units out there.
Note that the AA1 also has buggy BIOS -- OpenSolaris can't "see" the
cards (registers aren't properly initialized) unless they are present
when the unit first powers up.
But, why it works in windows?
The Microsoft PCI code base probably is more willing to "work around"
BIOSes that don't properly configure PCI configuration registers... this
is an outstanding RFE for Solaris.
The Windows code base also has some other unrelated quirks in it -- it
uses DAT3 for card presence detection instead of the card detect bit in
the sdhci controller, for example. (It also doesn't support MMC, which
is to blame for some of the bastardized controller hacks that mfgrs like
Ricoh have done to separate their MMC and SDcard handling into separate
PCI functions. Yes, that's a hardware workaround for a software bug!
Go figure -- its what happens when one software company has a virtual
monopoly...)
-- Garrett
Regards,
Maxim Levitsky
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