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

[Sergey Alyoshin]

On Fri, Dec 13, 2013 at 5:04 AM, Benoît Thébaudeau
<benoit.thebaudeau at advansee.com> wrote:
> On Friday, December 13, 2013 1:52:19 AM, Benoît Thébaudeau wrote:
>> Dear Sergey Alyoshin,
>>
>> 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?
>>
>> 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?
>
> Also note that the data sheets of the i.MX51 and i.MX53 both mention a dedicated
> VDD_FUSE pin, with several notes saying that it should not be powered if
> programming is not required in order to avoid inadvertently blowing fuses in
> read mode. These notes would not be required if this bit gating this supply by
> default really did exactly that. I think that it is rather an internal feature
> for Freescale only, e.g. to blow Freescale bits like UID in die production.

I apply 3.3V on VDD_FUSE pin and still without setting
EFUSE_PROG_SUPPLY_GATE bank 1 was not programmed on i.MX53.