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

[Ben Warren]

robert lazarski wrote:
> On 9/4/07, Ben Warren <bwarren at qstreams.com> wrote:
>   
>> David Hawkins wrote:
>>     
>>> Hi Robert,
>>>
>>>
>>>       
>>>> The big problem we have now: is this a hardware issue or a bdi config
>>>> issue? Aside from the flash we have 1GigaByte of DDR ram. Can anyone
>>>> help us track our flash issues down to be hardware, config file, or
>>>> some combination? The hardware guys think the board is fine.
>>>>
>>>>         
>>> Have you checked that the Flash is getting accessed?
>>>
>>>       
>> Very good point. I know you've made many changes since your initial
>> setup Robert. Did any of them make the chip select strobe?
>>     
>
> We now see the CE on the flash chip going from 3.3v to 0 on reset of
> the 8548. We also see the same behavior when issuing a mdh command on
> the bdi - however, we cannot see any activity whatsoever on the Ax
> pins on the spansion flash chip when trying read via the bdi and mdh.
>
>   
That's cool. Getting closer... You don't see activity on any of the 
address pins? You of course remember the goofy way that PowerPC bits are 
reversed, right? (i.e. local bus A30 should be wired to A0 on the flash 
chip, since it's a 16-bit device, A29 to A1 etc.)
> Getting deep into 8548, the "pin strapping" I believe is controlled by
> the POR Boot Mode Status Register (PORBMSR) in "20.4.1.2" in:
>
> http://www.freescale.com/files/32bit/doc/ref_manual/MPC8548ERM.pdf
>
> Reading the register PORBMSR we get: 0x86370000 which I'm reading as:
>
> 1 0000 110 00 11 0 11 100 00000000000000
>
> 0         BCFG = 1 The CPU is allowed to start fetching boot code.
> 1-4      reserved
> 5-7      ROM_LOC = 110 Local bus GPCM:16-bit (our local bus is 16bit)
> 8-9      reserved
> 10-11   BSCFG = 11 Boot sequencer disabled
> 12       reserved
> 13-15   Host/agent = PCI1/PCI-X and Serial RapidIO agent mode
> 16-31   reserved.
>
> Our flash is 128MB and we think we set the LAW correctly in the bdi
> config file as F8000000 .  In 4.3.1.3 however, it defaults to FF80000
> and says:
>
>  "If translation is to be performed to a page outside the default boot
> ROM address range defined in the MPC8548E (8 Mbytes at 0x0_FF80_0000
> to 0x0_FFFF_FFFF as defined in Section 4.4.3.3, "Boot ROM Location"),
> the external host or boot sequencer must then also set up a local
> access window to define the routing of the boot code fetch to the
> target interface that contains the boot code, because the BPTR defines
> only the address
> translation, not the target interface."
>
> Perhaps we're not doing that right?
>   
More fun than a barrel of monkeys. Maybe you should just pretend your 
device is only 8MB for now.

regards,
Ben