[U-Boot] [PATCH 1/1] arm: mx5: Add fuse supply gate enable in fsl_iim

[Sergey Alyoshin]

Hello, Benoît,

On Fri, Dec 13, 2013 at 4:52 AM, Benoît Thébaudeau
<benoit.thebaudeau at advansee.com> wrote:
> On Thursday, December 12, 2013 5:46:21 PM, Sergey Alyoshin wrote:
>> Enable fuse supply gate before fuse programming and disable after.
>>
>> Signed-off-by: Sergey Alyoshin <alyoshin.s at gmail.com>
>> Tested-by: Sergey Alyoshin <alyoshin.s at gmail.com>
>
> Have you also tested without this patch first too? On which SoC?

I have tried to write MAC address in fuse (bank 1) on i.MX53 custom board
and 'fuse sense' show no change, reboot show no change either.

I have not tested this on i.MX51, but this register and bit is the same on
i.MX51 with exactly the same description.  With this patch I have
successfully written MAC addresses on several i.MX53 boards.

In Linux 2.6.35 from Freescale this bit is also set for fuse programming,
e.g. in arch/arm/mach-mx5/mx51_babbage.c and arch/arm/mach-mx5/mx53_loco.c
in mxc_iim_enable_fuse().

> My tests had shown that this is not required on i.MX51. It's probably the same
> on i.MX53. I have not checked if i.MX25 and i.MX35 also have such a bit, but
> they also work fine as is. This is not even done by Freescale:
> http://git.freescale.com/git/cgit.cgi/imx/linux-2.6-imx.git/tree/drivers/char/mxc_iim.c?h=imx_3.0.35_4.1.0
>
> In the Reference Manual, nothing says in the IIM / fuse chapters that this bit
> is needed for proper programming. It is just described in the CCM register map,
> and nothing refers to it. It is perhaps only useful for test purposes. I'd vote
> for letting this bit untouched if possible.
>
> Fabio, do you have more information from Freescale about this bit?