Porting Au1x000 USB host controller on u-boot

Porting Au1x000 USB host controller on u-boot

[Rodolfo Giometti]

Hello,

I'm trying to implement support for USB host into u-boot. I
initialized the USB controller just as linux does, the EDs and the TDs
look like good in memory but the controller seems not well reading
them and on the bus I see random USB messages...

I think that there could be some problem on memory coherency... some
suggestion?

Thanks,

Rodolfo

-- 

GNU/Linux Solutions                  e-mail:    giometti@enneenne.com
Linux Device Driver                             giometti@gnudd.com
Embedded Systems                     		giometti@linux.it
UNIX programming                     phone:     +39 349 2432127

Re: Porting Au1x000 USB host controller on u-boot

[Sergei Shtylyov]

Hello,

Rodolfo Giometti wrote:

> I'm trying to implement support for USB host into u-boot. I
> initialized the USB controller just as linux does, the EDs and the TDs
> look like good in memory but the controller seems not well reading
> them and on the bus I see random USB messages...
> 
> I think that there could be some problem on memory coherency... some
> suggestion?

    Be sure to set Config0.OD (bit 19), it's proven to fix the USB-related 
lockups on Au1500 at least. See arch/mips/common/cputable.c for the CPU 
steppings where it must be set to mask various errata. Also, try to disable 
USB controller's DMA coherency in the USB enable register (there's a related 
errata in all Au1xx0 family) -- the Linux driver doesn't do this though, and 
this shouldn't matter unless you're modifying USB buffers on the fly. :-)
    Also, note that this magic bit may be write only, so make sure it's set on 
every write to CP0 Config0 reg. See this patch:

http://www.linux-mips.org/archives/linux-mips/2006-03/msg00243.html

> Thanks,
> 
> Rodolfo

WBR, Sergei

Re: Porting Au1x000 USB host controller on u-boot

[Sergei Shtylyov]

Hello,

Sergei Shtylyov wrote:

>> I'm trying to implement support for USB host into u-boot. I
>> initialized the USB controller just as linux does, the EDs and the TDs
>> look like good in memory but the controller seems not well reading
>> them and on the bus I see random USB messages...

>> I think that there could be some problem on memory coherency... some
>> suggestion?

>    Be sure to set Config0.OD (bit 19), it's proven to fix the 
> USB-related lockups on Au1500 at least. See arch/mips/common/cputable.c 

    arch/mips/au1000/common/cputable.c, I mean... :-)

WBR, Sergei

Re: Porting Au1x000 USB host controller on u-boot

[Sergei Shtylyov]

Hello, I wrote:

>> I'm trying to implement support for USB host into u-boot. I
>> initialized the USB controller just as linux does, the EDs and the TDs
>> look like good in memory but the controller seems not well reading
>> them and on the bus I see random USB messages...

>> I think that there could be some problem on memory coherency... some
>> suggestion?

> try to disable USB controller's DMA coherency in the USB enable register 
> (there's a related errata in all Au1xx0 family) -- the Linux driver 
> doesn't do this though, and this shouldn't matter unless you're 
> modifying USB buffers on the fly. :-)

    AND make sure every buffer/TD/ED is written back / invalidated from cache 
before the OHCI accesses them since the cache coherency on Au1xx0 is b0rken!

WBR, Sergei

Re: Porting Au1x000 USB host controller on u-boot

[Sergei Shtylyov]

Hello, I wrote:

>> I'm trying to implement support for USB host into u-boot. I
>> initialized the USB controller just as linux does, the EDs and the TDs
>> look like good in memory but the controller seems not well reading
>> them and on the bus I see random USB messages...

>> I think that there could be some problem on memory coherency... some
>> suggestion?

> try to disable USB controller's DMA coherency in the USB enable register 
> (there's a related errata in all Au1xx0 family) -- the Linux driver 
> doesn't do this though, and this shouldn't matter unless you're 
> modifying USB buffers on the fly. :-)

    AND make sure every buffer/TD/ED is written back / invalidated from cache 
before the OHCI accesses them since the cache coherency on Au1xx0 is b0rken!

WBR, Sergei

Re: Porting Au1x000 USB host controller on u-boot

[Rodolfo Giometti]

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On Thu, May 04, 2006 at 09:16:19PM +0400, Sergei Shtylyov wrote:
> 
>    AND make sure every buffer/TD/ED is written back / invalidated from 
>    cache before the OHCI accesses them since the cache coherency on Au1xx0 is 
> b0rken!

Mmm... good suggestion! :) How can I invalidated the cache? Can you
please show me some example code?

Thanks _a lot_!

Rodolfo

-- 

GNU/Linux Solutions                  e-mail:    giometti@enneenne.com
Linux Device Driver                             giometti@gnudd.com
Embedded Systems                     		giometti@linux.it
UNIX programming                     phone:     +39 349 2432127

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Re: Porting Au1x000 USB host controller on u-boot

[Sergei Shtylyov]

Hello.

Rodolfo Giometti wrote:

>>   AND make sure every buffer/TD/ED is written back / invalidated from 
>>   cache before the OHCI accesses them since the cache coherency on Au1xx0 is 
>>b0rken!

    Or, better yet, access TD/ED (and, if possible, the buffers) via uncached 
KSEG1 only.

> Mmm... good suggestion! :) How can I invalidated the cache? Can you
> please show me some example code?

    Dig in arch/mips/mm/c-r4k.c...

> Thanks _a lot_!
> 
> Rodolfo

WBR, Sergei