[meta-freescale] speed of /dev/i2c-2 in imx6q sabre-lite

[Thanassis Silis]

Eric,
thank you very much for the answer (I have compiled kernel 3.0.35_1.1.0 by the way, but the code hasn't changed since then).
I do have a question (in my limited kernel knowledge) :)
https://github.com/boundarydevices/linux-imx6/blob/boundary-imx_3.0.35_4.0.0/drivers/i2c/busses/i2c-imx.c#L63

this looks like a module, but as I see in my sabrelite's  /lib/modules/3.0.35-1.1.0+g2dc5560
modules.builtin:92:kernel/drivers/i2c/busses/i2c-imx.ko
it is built in the kernel.

What is the purpose of i2c-imx and how does it relate to imx* boards?

Thank you for your help!

> Date: Tue, 13 Aug 2013 11:30:00 -0700
> From: eric.nelson at boundarydevices.com
> To: djnass_18 at hotmail.com
> CC: meta-freescale at yoctoproject.org
> Subject: Re: [meta-freescale] speed of /dev/i2c-2 in imx6q sabre-lite
> 
> Hi Thanassis,
> 
> On 08/13/2013 11:03 AM, Thanassis Silis wrote:
> > Hello everyone,
> > I am unaware as to who sets clock speed on the i2c bus and specifically
> > on the /dev/i2c-2 which is exposed on the board so as to drive external
> > equipment.
>  >
> > I am looking into the linux-boundary kernel files in yocto (dylan) build
> > dir, but I cannot figure out where that is set.
> > To be honest I don't even know if i'll find that info there, but it
> > seems like the right place to start (after googling about it of course).
> >
> > So who determined the speed (standard mode, fast mode, etc) for the
> > external i2c? if it is a driver , which one should I be looking for?
> >
> 
> This structure defines the speed of the I2C bus:
> 	https://github.com/boundarydevices/linux-imx6/blob/boundary-imx_3.0.35_4.0.0/arch/arm/mach-mx6/board-mx6_nitrogen6x.c#L434
> 
> To change it for i2c-2 by itself, you'll need to make a copy of
> that, change the speed value and pass the copy to the routine
> imx6q_add_imx_i2c():
> 	https://github.com/boundarydevices/linux-imx6/blob/boundary-imx_3.0.35_4.0.0/arch/arm/mach-mx6/board-mx6_nitrogen6x.c#L1320
> 
> > The reason is I am trying to drive some TMC222 low-power stepper motor
> > control ICs, but they do not respond.
> > Note I have successfully connected a number of other i2c ICs (among
> > others the pca9505x).
> >
> > An answer is not necessary. Any pointers as to how to go about it , so I
> > can learn about this is more than welcome.
> > Thank you for your help.
> >
> 
> This should be straightforward.
> 
> Let me know if you have any trouble.
> 
> Regards,
> 
> 
> Eric
> 
> 
 		 	   		  
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