[U-Boot-Users] Proposal to add "ispeed" (I2C speed) command

[Wolfgang Denk]

In message <20641.216.110.51.8.1078416617.squirrel at www.orkun.us> you wrote:
> > Just configure the I2C clock for the maximum  allowable  speed  right
> > from the beginning.
> 
> You can have 100khz and 400khz capable devices accessible to the master.
> You can run everything at 100khz but you will not be taking full
> advantange of 400khz devices.

Rigth. But on such a system you cannot run the bus at 400 kHz as this
would be out of spec for the 100 kHz devices.

> Philips AN10216-01 (I2C Manual) Dated March 24, 2003, Page 24 describes
> how a system can run both 100kHz devices and 400kHz devices on the same
> bus and access 400kHz devices at 400kHz using I2C bus repeater such as
> PCA9515.
> 
> I understand this might not be useful for everyone so that is why I
> proposed to make it an optional command that is compiled in only if
> CONFIG_I2C_ISPEED is defined.

I don't think this is useful.

What exactly are you trying to do that the speed makes any difference
for you? Remember, this is a boot loader, not an operating system.


Best regards,

Wolfgang Denk

-- 
Software Engineering:  Embedded and Realtime Systems,  Embedded Linux
Phone: (+49)-8142-4596-87  Fax: (+49)-8142-4596-88  Email: wd at denx.de
Conquest is easy. Control is not.
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