Host USB issue on MPC8272

Host USB issue on MPC8272

[David Beamonte]

Hi,

I'm trying to use USB host controller in an MPC8272. My board is based 
on ADS8272 with few modifications: FLASH and SDRAM models are different 
and several GPIOs and interrupts are not connected the same way.

The driver we are using is CPM2USB from sourceforge with a 2.6.21.5 
kernel version.

With my ADS8272 board it works quite fine, but with our board, the 
processor hangs when it starts sending data to the device.

This issue seems to be related to one problem that we have always had. 
We can't configure buffers of SMCs, SCCs, etc, to be in SDRAM, because 
the processor hangs. We always have to configure buffers in DPRAM. In 
other drivers this has not been a problem, because the buffer size is 
not very large, so we can allocate it in DPRAM, but for this one, the 
buffer size is 0x8000 (32Kb) which exceeds DPRAM size.

Has anybody had the same problem? Can it be an USB specific problem or a 
general one?

Thanks,

David

Re: Host USB issue on MPC8272

[Scott Wood]

David Beamonte wrote:
> This issue seems to be related to one problem that we have always had. 
> We can't configure buffers of SMCs, SCCs, etc, to be in SDRAM, because 
> the processor hangs. We always have to configure buffers in DPRAM. In 
> other drivers this has not been a problem, because the buffer size is 
> not very large, so we can allocate it in DPRAM, but for this one, the 
> buffer size is 0x8000 (32Kb) which exceeds DPRAM size.
> 
> Has anybody had the same problem? Can it be an USB specific problem or a 
> general one?

Make sure that BCR[PLDP] is not set, as per erratum SIU18.

-Scott

Re: Host USB issue on MPC8272

[David Beamonte]

I have checked that bit and it is not set. In fact, that register has 
the same value as the one in our ADS8272 (0x100c0000), which works.

Anyway, it must be an issue of this kind, from the beginning I have 
thought that we have a problem of arbitration of the bus that makes the 
processor hang when the CPMs try to access external memory. Can it be a 
problem of SDRAM configuration, wait-states or refresh times?

Thanks Scott,

David


Scott Wood escribió:
> David Beamonte wrote:
>> This issue seems to be related to one problem that we have always 
>> had. We can't configure buffers of SMCs, SCCs, etc, to be in SDRAM, 
>> because the processor hangs. We always have to configure buffers in 
>> DPRAM. In other drivers this has not been a problem, because the 
>> buffer size is not very large, so we can allocate it in DPRAM, but 
>> for this one, the buffer size is 0x8000 (32Kb) which exceeds DPRAM size.
>>
>> Has anybody had the same problem? Can it be an USB specific problem 
>> or a general one?
>
> Make sure that BCR[PLDP] is not set, as per erratum SIU18.
>
> -Scott
>

Re: Host USB issue on MPC8272

[David Beamonte]

Has anybody had a similar problem accessing external memory from CPMs?

Any idea on something I can try?

What is more critical? Accessing slow or quick external devices?

David


David Beamonte escribió:
> I have checked that bit and it is not set. In fact, that register has 
> the same value as the one in our ADS8272 (0x100c0000), which works.
>
> Anyway, it must be an issue of this kind, from the beginning I have 
> thought that we have a problem of arbitration of the bus that makes 
> the processor hang when the CPMs try to access external memory. Can it 
> be a problem of SDRAM configuration, wait-states or refresh times?
>
> Thanks Scott,
>
> David
>
>
> Scott Wood escribió:
>> David Beamonte wrote:
>>> This issue seems to be related to one problem that we have always 
>>> had. We can't configure buffers of SMCs, SCCs, etc, to be in SDRAM, 
>>> because the processor hangs. We always have to configure buffers in 
>>> DPRAM. In other drivers this has not been a problem, because the 
>>> buffer size is not very large, so we can allocate it in DPRAM, but 
>>> for this one, the buffer size is 0x8000 (32Kb) which exceeds DPRAM 
>>> size.
>>>
>>> Has anybody had the same problem? Can it be an USB specific problem 
>>> or a general one?
>>
>> Make sure that BCR[PLDP] is not set, as per erratum SIU18.
>>
>> -Scott
>>
>
>