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

[Roger Quadros <rogerq@ti.com>]

Hi Marek,

On 07/11/2013 03:35 PM, Marek Vasut wrote:
> Dear 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@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.
> 
> You'd need to implement this for each of the xHCIs

OK.
> 
>>>>> +
>>>>
>>>> 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.
> 
> Then it would also work in usb_lowlevel_init() ?

It should as long as we place the "release reset" after EHCI controller
has started. Maybe safer to put it in the end of usb_lowlevel_init().

cheers,
-roger