[U-Boot] mx51evk: Add CONFIG_REVISION_TAG

FSL 2.6.35 kernel assumes that the bootloader passes the CONFIG_REVISION_TAG
information.

If this data is not present, the kernel misconfigures the TZIC, which results in
the timer interrupt handler never being called, so the kernel deadlocks while
calibrating its delay.

Suggested-by: Greg Topmiller <Greg.Topmiller@jdsu.com>
Signed-off-by: Benoît Thébaudeau <benoit.thebaudeau@advansee.com>
Cc: Stefano Babic <sbabic@denx.de>
Cc: Fabio Estevam <festevam@gmail.com>
---
 .../board/freescale/mx51evk/mx51evk.c              |    5 +++++
 .../include/configs/mx51evk.h                      |    1 +
 2 files changed, 6 insertions(+)

Hi Benoît ,

On Mon, Sep 17, 2012 at 4:04 PM, Benoît Thébaudeau
<benoit.thebaudeau@advansee.com> wrote:

> +u32 get_board_rev(void)
> +{
> +       return get_cpu_rev();
> +}

Is this enough?  Looking at FSL U-boot there is also a:

static inline void set_board_rev(void)
{
	if ((__REG(GPIO1_BASE_ADDR + 0x0) & (0x1 << 22)) == 0)
		system_rev |= BOARD_REV_2_0 << BOARD_VER_OFFSET;

}

On mx53loco I had very weird problems when kernel was running and it
took me sometime to find out that it was due to wrong detection of the
board revision, so I suggest to double check this to avoid this kind
of problem on mx51evk too.

Regards,

Fabio Estevam

Hi Greg,

On Tue, Sep 18, 2012 at 10:00 AM, Greg Topmiller
<Greg.Topmiller@jdsu.com> wrote:
> Fabio/Benoit,
>
> I tried the get_board_rev alone and it worked on my mx51evk.
>
> In the FSL u-boot version I am using the set_board_rev is:
> static inline void set_board_rev(int rev)
> {
>         system_rev |= (rev & 0xF) << 8;
> }

So you should call it as "set_board_rev(BOARD_REV2)" , where:
#define BOARD_REV2 0x1

I don't think we have boards older than rev2 anymore.

Looking at the FSL kernel, there are are some tests for "if
(board_is_rev(BOARD_REV_2))"
and they should return true from what I can see from the schematics.

 841                 if (board_is_rev(BOARD_REV_2))
 842                         /* BB2.5 */
 843                         ret = gpio_get_value(BABBAGE_SD2_CD_2_5);
 844                 else
 845                         /* BB2.0 */
 846                         ret = gpio_get_value(BABBAGE_SD2_CD_2_0);
 847                 return ret;

With the original patch from Benoit "board_is_rev(BOARD_REV_2)" would
return falsem which would then assign the wrong SD2 card detect pin,
for example.

Regards,

Fabio Estevam

Fabio,

On Tuesday, September 18, 2012 5:24:57 AM, Fabio Estevam wrote:
> Hi Benoît ,
> 
> On Mon, Sep 17, 2012 at 4:04 PM, Benoît Thébaudeau
> <benoit.thebaudeau@advansee.com> wrote:
> 
> > +u32 get_board_rev(void)
> > +{
> > +       return get_cpu_rev();
> > +}
> 
> Is this enough?  Looking at FSL U-boot there is also a:
> 
> static inline void set_board_rev(void)
> {
> 	if ((__REG(GPIO1_BASE_ADDR + 0x0) & (0x1 << 22)) == 0)
> 		system_rev |= BOARD_REV_2_0 << BOARD_VER_OFFSET;
> 
> }

I have a question regarding this code: Is it normal that it does not enable a
weak pull-up (100 k) on UART3_RXD's pad? According to the schematic history, the
pull-down R6001 (10 k) has been added to UART3_RXD for revision 2. By default,
the pad of this pin has its keeper enabled, not its pull, so everything is fine
with this code for revision 2, but what about revision 1?

To reformulate my question: Was there anything on this board before R6001
inputting a high level on UART3_RXD, or does the pad keeper guarantee some
default init level by design if the pin is externally left floating?

Best regards,
Benoît

Benoît,

On Tue, Sep 18, 2012 at 1:01 PM, Benoît Thébaudeau
<benoit.thebaudeau@advansee.com> wrote:

> I have a question regarding this code: Is it normal that it does not enable a
> weak pull-up (100 k) on UART3_RXD's pad? According to the schematic history, the
> pull-down R6001 (10 k) has been added to UART3_RXD for revision 2. By default,
> the pad of this pin has its keeper enabled, not its pull, so everything is fine
> with this code for revision 2, but what about revision 1?

I don't know the history about this change between rev1 versus rev2. I
would need to check with the board designer.

Regards,

Fabio Estevam