[U-Boot] Detecting board revision that needs to be done after relocation

[U-Boot] Detecting board revision that needs to be done after relocation

[Fabio Estevam]

Hi,

I need to provide a get_board_rev() function that depends on I2C probe
of a PMIC to decide between the board revision.

I2C is only available after relocation, so what is the correct way to
"delay" get_board_rev, so that it gets called only at a time when I2C
is ready?

Thanks,

Fabio Estevam

[U-Boot] Detecting board revision that needs to be done after relocation

[Marek Vasut]

Dear Fabio Estevam,

> Hi,
> 
> I need to provide a get_board_rev() function that depends on I2C probe
> of a PMIC to decide between the board revision.
> 
> I2C is only available after relocation,

On arm? Not at all ;-) check arch/arm/lib/board.c

> so what is the correct way to
> "delay" get_board_rev, so that it gets called only at a time when I2C
> is ready?

Well ... implement board-specific hack in your boardfile that detects the PMIC 
early?

> Thanks,
> 
> Fabio Estevam
> _______________________________________________
> U-Boot mailing list
> U-Boot at lists.denx.de
> http://lists.denx.de/mailman/listinfo/u-boot

Best regards,
Marek Vasut

[U-Boot] Detecting board revision that needs to be done after relocation

[Fabio Estevam]

On Tue, May 29, 2012 at 11:45 AM, Marek Vasut <marek.vasut@gmail.com> wrote:

> Well ... implement board-specific hack in your boardfile that detects the PMIC
> early?

Yes, you are right. This works ;-)

Regards,

Fabio Estevam

[U-Boot] Detecting board revision that needs to be done after relocation

[Andrew E. Mileski]

On 05/28/2012 11:25 PM, Fabio Estevam wrote:
>
> I need to provide a get_board_rev() function that depends on I2C probe
> of a PMIC to decide between the board revision.
>
> I2C is only available after relocation, so what is the correct way to
> "delay" get_board_rev, so that it gets called only at a time when I2C
> is ready?

I2C is usually available earlier, as it is used to read the SPD on 
memory modules.

When I last did it, I had to change U-Boot slightly to support a second 
I2C bus, as the bus selection variable was located in flash before 
relocation (very old version of U-Boot, so may not apply still).

I've only had a problem using I2C very early in the boot sequence, like 
before the system clocks have been setup, then the solution to that was 
to just use a GPIO strapping instead for clock selection.

-- 
Andrew E. Mileski

[U-Boot] Detecting board revision that needs to be done after relocation

[Hebbar, Gururaja]

On Tue, May 29, 2012 at 08:55:34, Fabio Estevam wrote:
> Hi,
> 
> I need to provide a get_board_rev() function that depends on I2C probe
> of a PMIC to decide between the board revision.
> 
> I2C is only available after relocation, 

Not necessarily. You can use i2c probe & read even before relocation provided
they are no data from bss section being used. 

Look at below commits for details

http://git.denx.de/?p=u-boot.git;a=commitdiff;h=0b620ec97e05ddb09714d127a7880333fc4008fb

http://arago-project.org/git/projects/?p=u-boot-am33x.git;a=commitdiff;h=4825603ea6b2f70df2986bb489c4179383c76b5a

http://arago-project.org/git/projects/?p=u-boot-am33x.git;a=commitdiff;h=0ffb997b4d2fa3fd6e99310d7eb4d034cc78d63e



>so what is the correct way to
> "delay" get_board_rev, so that it gets called only at a time when I2C
> is ready?
> 
> Thanks,
> 
> Fabio Estevam
> _______________________________________________
> U-Boot mailing list
> U-Boot at lists.denx.de
> http://lists.denx.de/mailman/listinfo/u-boot
> 


Regards, 
Gururaja