[U-Boot-Users] minimum bdi config to read flash on 85xx

[David Hawkins <dwh@ovro.caltech.edu>]

Hi Luiz,

> This is Luiz and I'm working with Robert in this  project.

Glad to hear he's got someone to grow grey hairs
with ... if it hasn't fallen out yet.

> Actually, I'm a hardware guy.

So am I ... this week :)

> I read your messages and it seems you're right. However, 
> before introducing these changes on the board, we decided
> to verify all flash circuitry and we noticed the following:
> 
> CE# is OK!
> WE# is OK!
> OE# is OK!
> 
> We verified it using a scope and triggering CE# pin. After that, we 
> tried to write to flash through BDI2000 using "mm" command. Again with a 
> scope we checked each address line and apparently everything is fine 
> with the address.

I think that after the processor boots LAD[0:31] activate
for each address access, its only during boot that LAD[27:31]
do not toggle, and you have to use LA[27:31]. So its
that confirmation of the address toggles in this case just
confirms that the LAD[27:31] bits toggle.

On the bright-side, it sounds like you have the bit
ordering correct ([27:30])... just not the right bits
(LAD vs LA).

> We also checked the data being written, and it's ok 
> too. After that, in order to validate the written, we read the same 
> address we had just written. But we got a different value. Therefore we 
> are not writing correctly to flash.

Have you tried using simple CFI flash commands;
read the manufacturer ID, read the device ID,
read the sector protection? Don't bother with
BDI Flash commands just yet, just use memory
read/write commands.

> Ok, after all, we fixed our board following your tips.
> We connected LA[27:30] to A[3:0] and A[4:25] to LBA[26:5].
> But we got the same bad result. I mean we read a wrong data.
> 
> After, we changed flash access time, decreasing it. And the
> problem persisted. We changed flash chip and nothing happened.
> 
> Actually I'm afraid because I can't see what else we can verify
> on hardware.
> 
> My opinion is we have mistakes on configuration file. I'm not sure if we 
> are configuring all registers correctly.
> 
> Do you think it would be helpful if I send you our flash schematic and 
> our configuration file?

Sure, no guarantees, you can send me a copy, or send
a link to the group. I'm not too knowledgeable on BDI
config files yet, as I don't have my custom hardware.
However, I have looked at a few hardware designs, so
perhaps I'll spot something on the schematic. The
peripherals seem to be pretty similar between the
PowerQUICCs, so I'll dig up a working configuration
file, and look at the difference in register settings.

What is your Flash? Eg. if its say a Spansion device,
do you have WP# tied high, BYTE# tied low/high, etc?
Are there any address pins left floating?

Do you have a logic analyzer available? If you did,
you'd be able to look at the flash controls and write-data
and convince yourself that your Flash programming
sequence was correct.

The best advice at the moment, is to access your Flash
configuration using manual read/write sequences.

Cheers,
Dave