[i2c] read/write access to SMBus on a PCIexpress slot

[Jean Delvare]

Hi Walter,

On Mon, 25 Jun 2007 17:05:34 +0200, Walter F.J. Mueller wrote:
>  b. what is the data rate I can expect in practice ? A typical
>     FPGA for such an application, like a Virtex-4 FX60, has 20 MBit
>     config data. With 20 kbit/sec, which is 20% of nominal the SMBus
>     wire speed, it would take 1000 sec to do a firmware upgrade.
>     That's still ok, but much slower would be painfull. If somebody
>     has experience with this somewhat unusual sort of bulk data
>     transfer over SMBus please drop me a note.

Depends on the SMBus master. See this post of mine a couple weeks ago:
http://lists.lm-sensors.org/pipermail/i2c/2007-May/001387.html

Note that all the Linux SMBus master drivers (for PC hardware) are
poll-based, so in practice we waste a lot of time waiting, and the
speed on the wire doesn't matter that much. If you really care about
the SMBus speed, you'll have to add interrupt support.

-- 
Jean Delvare