> I guess this discussion is in the TS-7000 group since TS delivers
only
> a binary object file SD.o for SD card support. Obviously this is a
> stumbling block for those of us who prefer 2.6 kernels.
A 2.6 driver could still be made without TS. TS delivers a OS-
independent gcc or IAR compiled object file sdcore.o that contains a
simple and stable C API to access the SD card. We publish a sdcard.c
Linux API "shim" that uses the sdcore.o routines (sdread(), sdwrite
(), sdreset()) to implement Linux 2.4's block driver interface. We
have several people using this .o in their own non-Linux applications
running on the raw hardware without an OS.
>
> I can see why TS prefers this, (SD NDA in effect when they bought
the
> earlier spec from the association), but are there any other issues?
> Is there TS ip that needs to be protected?
>
> Can TS take a look at the released spec, and say "Yes, that has a
good
> chance of working with our SD slot via our FPGA"? Or "No, it's
close
> but you need these changes ..."?
TS created an SD host controller core in Verilog that only uses 200
LUTs on a CPLD and 4 8bit registers. This is very small compared to
companies selling standard SD logic cores. Existing soft cores on
the market require much larger and expensive FPGAs.
Since the core is so small (20 times smaller than the SDHC), it
doesn't even come close to resembling the standard SDHC, so existing
SDHC drivers have no chance of working. The hardware is basically a
GPIO port with some SD specific accelerations-- most of the
complexity and IP is in the sdcore.o routines.
Yes, we do have an interest in protecting this IP. The smallness of
the logic core and the simplicity and OS-independence of the
sdcore.o "BIOS" make it valuable. We use this IP with others to
attract customers for our custom designs business.
>
> Of course I can't expect TS to support 2.6 kernels; I disagree with,
> but respect their decision. But a few hints to help a community
> written & supported SD driver would mean everybody wins.
Our large customers freak out when the board silkscreen changes
colors-- transitioning our shipping TS-7000's to 2.6 would be chaos,
especially knowing now that Linux considers backward compatibility
nonsensical.
Our next SBC will be 2.6 based however.
//Jesse Off
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