USB support on i.MX27

[Valentin Longchamp]

Hello all,

Eric Bénard wrote:
> Valentin Longchamp a écrit :
>> Alan Carvalho de Assis wrote:
>>> On 12/1/09, Daniel Mack <daniel at caiaq.de> wrote:
>>>> Hmm, I don't follow. You added some debug output and it started 
>>>> working,
>>>> is that what you say? Do we possibly need memory barriers somewhere?
>>>>
>>>
>>> Basically it, but I will do more tests to isolate the issue.
>>>
>>> In fact there is a board where the issue remain, but using old kernel
>>> (2.6.22) both work.
>>
>> I am also investigating this issue. The same happens sometimes with my 
>> USB host with ULPI-ISP1504, but it never happens with the USB slave 
>> with the exact same hardware ULPI-ISP1504, that's why I have the 
>> feeling that it's a purely software issue.
>>
> we once met a similar problem on i.MX27 : in fact, during IOMUX 
> configuration, some pins were togled on the ULPI and the ISP1504 was 
> taking this toggles as a command and was taking control of the ULPI bus 
> which means the IMX wasn't anymore able to talk to it through ULPI. Just 
> reseting the ISP1504 allawed the boot to continue fine.
> Maybe your issue is similar to this.
> 

I have found a fix to this issue, and it looks a bit like what Eric just 
described. I will post a patch in the next minutes and it would be nice 
if (at least) Alan and Daniel could test it to see if it fixes the 
problem for them too.

With the patch, I have never noticed a problem during the whole 
afternoon (around 30-35 reboots with ULPI init).

Val