[U-Boot] [PATCH v2 1/3] ARM: Tegra: FDT: Add USB EHCI function for T30/T114

[Stephen Warren <swarren@wwwdotorg.org>]

On 06/17/2013 02:39 PM, Marek Vasut wrote:
> Dear Thierry Reding,
> 
>> On Sun, Jun 16, 2013 at 10:48:45PM +0200, Marek Vasut wrote:
>>> Dear Thierry Reding,
>>>
>>>> On Sat, Jun 15, 2013 at 11:28:25PM +0200, Marek Vasut wrote:
>>>>> Dear Thierry Reding,
>>>>>
>>>>>> On Fri, Jun 14, 2013 at 06:41:40PM +0800, Jim Lin wrote:
>>>>>> [...]
>>>>>>
>>>>>>> diff --git a/board/nvidia/dts/tegra30-beaver.dts
>>>>>>> b/board/nvidia/dts/tegra30-beaver.dts
>>>>>>
>>>>>> [...]
>>>>>>
>>>>>>> @@ -68,4 +69,9 @@
>>>>>>>
>>>>>>>  		status = "okay";
>>>>>>>  		bus-width = <8>;
>>>>>>>  	
>>>>>>>  	};
>>>>>>>
>>>>>>> +
>>>>>>> +	usb at 7d008000 {
>>>>>>> +		nvidia,vbus-gpio = <&gpio 61 3>; /* PH5,
>>>
>>> USB13_VBUS_PULLUP */
>>>
>>>>>> This doesn't work for me on Beaver. I need to turn the above line
>>>>>> into
>>>>>>
>>>>>> this:
>>>>>> 	nvidia,vbus-gpio = <&gpio 236 0>; /* PDD4 */
>>>>>>
>>>>>> PDD4 is the correct GPIO according to the schematics and the pin is
>>>>>> high-active. Also as far as I can tell, 3 is not a meaningful value
>>>>>> for the U-Boot GPIO bindings. Only the value 1 (low-active) is
>>>>>> used.
>>>>>>
>>>>>> With that change applied on top of your patches I can see that a
>>>>>> USB flash drive connected to USB3 is indeed powered. However I
>>>>>> noticed
>>>>>>
>>>>>> something strange. When I try to use USB, I get this:
>>>>>> 	Tegra30 (Beaver) # usb start
>>>>>> 	(Re)start USB...
>>>>>> 	USB0:   set_host_mode: GPIO 236 high
>>>>>> 	USB EHCI 1.00
>>>>>> 	scanning bus 0 for devices... 1 USB Device(s) found
>>>>>> 	
>>>>>> 	       scanning usb for storage devices... 0 Storage Device(s)
>>>>>> 	       found scanning usb for ethernet devices... 0 Ethernet
>>>>>> 	       Device(s) found
>>>>>>
>>>>>> So no storage device is detected, even though a USB flash drive is
>>>>>> connected and powered properly. If I repeat the same command,
>>>>>> however,
>>>>>>
>>>>>> the storage device is detected:
>>>>>> 	Tegra30 (Beaver) # usb reset
>>>>>> 	(Re)start USB...
>>>>>> 	USB0:   set_host_mode: GPIO 236 high
>>>>>> 	USB EHCI 1.00
>>>>>> 	scanning bus 0 for devices... 2 USB Device(s) found
>>>>>> 	
>>>>>> 	       scanning usb for storage devices... 1 Storage Device(s)
>>>>>> 	       found scanning usb for ethernet devices... 0 Ethernet
>>>>>> 	       Device(s) found
>>>>>>
>>>>>> Any idea what might be going on here?
>>>>>
>>>>> Try waiting a little after setting the GPIO maybe? The drive might
>>>>> need some time to settle.
>>>>
>>>> I can make it work on the first invocation of "usb start" by adding a
>>>> rather long mdelay() at the very end of ehci_hcd_init() in the Tegra
>>>> EHCI driver. The magic value seems to be 853 ms. 852 ms wasn't enough
>>>> in any of the test runs. 853 ms always worked.
>>>>
>>>> However 850+ ms seems like a very long time for the device to settle,
>>>> and keeping it in the driver probably isn't a good idea. Furthermore I
>>>> cannot reproduce the same issue with a newer flash drive, which works
>>>> fine with no additional delays.
>>>
>>> Try reverting 020bbcb "usb: hub: Power-cycle on root-hub ports" ...
>>> there's a thread in the ML that it caused issues.
>>
>> I reverted the following two patches:
>>
>> 	0bf796f usb: hub: Parallelize power-cycling of root-hub ports
>> 	020bbcb usb: hub: Power-cycle on root-hub ports
>>
>> because it wasn't trivial to revert only 020bbcb alone. However it
>> didn't change anything regarding the problem I was seeing.
>>
>> Thierry
> 
> Ok, this looks ugly and calls for a bisect. Can you check it ? I'll try to test 
> if USB works for me on some EHCI-enabled device.

The problem is definitely caused by 020bbcb "usb: hub: Power-cycle on
root-hub ports"; I reverted just that locally and it fixed my problems.