[U-Boot] [[PATCH v2 5/6] USB: ehci: Add a weak function for resetting devices

[Roger Quadros]

On 07/11/2013 02:16 AM, Dan Murphy wrote:
> On 07/10/2013 05:20 PM, Marek Vasut wrote:
>> Dear Dan Murphy,
>>
>>> Add a __weak function that can be overridden to reset devices
>>> attached to an ehci devices after the FEAT_POWER has been submitted
>>>
>>> Signed-off-by: Dan Murphy <dmurphy at ti.com>
>>> ---
>>>  drivers/usb/host/ehci-hcd.c |    7 +++++++
>>>  1 file changed, 7 insertions(+)
>>>
>>> diff --git a/drivers/usb/host/ehci-hcd.c b/drivers/usb/host/ehci-hcd.c
>>> index 706cf0c..fdd3994 100644
>>> --- a/drivers/usb/host/ehci-hcd.c
>>> +++ b/drivers/usb/host/ehci-hcd.c
>>> @@ -616,6 +616,11 @@ __weak uint32_t *ehci_get_portsc_register(struct
>>> ehci_hcor *hcor, int port) return (uint32_t *)&hcor->or_portsc[port];
>>>  }
>>>
>>> +__weak void ehci_reset_attached_devices(int port)
>>> +{
>>> +	return;
>>> +}

Does this function need to be ehci specific? Other USB controllers might also
need such a function.

>>> +
>> Can the reset not happen elsewhere?
> I have tried to move this around and keep this out of this file completely but nothing else seems to work.
> 
> For port 2 where the USB3530 is we don't have the issue the 3530 enumerates properly.
> 
> I did not see any information in the data sheet eluding to a timing issue.

This is the information I had received earlier from SMSC about USB3503A hub

"You need the host up and running, and ready to go, THEN negate RESET_N.  That is probably 95% of the issues."

Please make sure the following sequence is done.

- power up hub (RESET is active at this point).
- start USB controller
- wait a few ms
- release hub RESET.

giving a quick look at the u-boot code it seems you need to release the hub reset
after usb_lowlevel_init() _OR_ usb_init() returns.

cheers,
-roger