[U-Boot] [PATCH] usb: hub: allow pgood_delay to be specified via env

[Tim Harvey]

On Tue, Apr 7, 2015 at 8:34 AM, Stephen Warren <swarren at wwwdotorg.org> wrote:
> On 04/07/2015 08:52 AM, Tim Harvey wrote:
>>
>> On Mon, Apr 6, 2015 at 7:58 AM, Marek Vasut <marex at denx.de> wrote:
>>>
>>> On Monday, April 06, 2015 at 04:05:07 PM, Tim Harvey wrote:
>>>>
>>>> Some USB devices break the spec and require longer warm-up times. Allow
>>>> the usb_pgood_delay env variable to override the calculated time.
>>>>
>>>> I have encountered this specficically with several different
>>>> sized/branded
>>>> USB sticks with VID:PID 058f:6387 (Alcor Micro Corp. Transcend JetFlash)
>>>> where I need to set usb_pgood_delay to 2000ms to make them detectable.
>>>>
>>>> Signed-off-by: Tim Harvey <tharvey at gateworks.com>
>>>
>>>
>>> Hi!
>>>
>>> this looks like a good idea. I have a hint for improvement -- in case you
>>> get a timeout waiting for the device to be detected, maybe the error
>>> message
>>> should mention that you can try setting this env variable and try again ?
>>>
>>> Best regards,
>>> Marek Vasut
>>
>>
>> Marek,
>>
>> I'm not sure what 'failed detect' would be appropriate though. In my
>> case I was dealing with storage devices so I think what you are
>> proposing is that on a 'usb start' if 0 storage devices are found
>> display a message such as:
>>
>> No storage devices found - if a connected device is not being detected
>> try setting usb_pgood_delay env var to something above the 1000ms time
>> the USB spec allows
>
>
> That seems like something better for the documentation that at run-time.
> There's no reason to believe that the user has any USB storage devices
> plugged in.
>
>> Sounds a bit verbose and I'm not clear if it should be limited to USB
>> storage devices or other supported devices (I'm betting its just the
>> storage ones that often break the spec).
>>
>> Stephen, what do you think? You and I discussed adding such an env var
>> about a year ago.
>
>
> If there is some kind of error that's actively detected, it may make sense
> to print some kind of message. However, if the symptoms are that devices
> simply don't appear on the bus and there's no reason to believe any are
> actually plugged in, that fells different.

No error... just failure to detect storage device. I agree such a
message for people using 'usb start' for some other usb device is not
cool.

Let's leave it as-is then if there are no complaints.

Tim