[U-Boot] [PATCH 1/1] dwc2 USB controller hangs with lan78xx

[andrew thomas]

On 06/21/2018 01:37 AM, Peter Robinson wrote:
> On Mon, Jun 18, 2018 at 7:56 PM, Andrew Thomas <andrew.thomas at oracle.com> wrote:
>> This bug is the combination of dwc2 USB controller and lan78xx
>> USB ethernet controller, which is the combination in use on
>> the Raspberry Pi Model 3 B+.
>>
>> When the host attempts to receive a packet, but a packet has not
>> arrived, the lan78xx controller responds by setting BIR
>> (Bulk-In Empty Response) to NAK. Unfortunately, this hangs
>> the USB controller and requires the USB controller to
>> be reset.
>>
>> The fix proposed is to have the lan78xx controller respond
>> by setting BIR to ZLP.
>>
>> Signed-off-by: Andrew Thomas <andrew.thomas at oracle.com>
> Tested-by: Peter Robinson <pbrobinson at gmail.com>
>
> Tested on the RPi 3B+ and certainly improves this situation a number
> of Fedora users have seen.

Thanks for testing!

One odd, and inexplicable, issue I have encountered is that
some VGA monitors will cause the dwc2/lan78xx combination to fail.

I have a DVI based monitor, which causes the failure.
Whereas an HDMI monitor works fine. I hesitate to
guess why this is.

For the monitor which causes problems, I am using a config
file with:

hdmi_ignore_edid=0xa5000080
hdmi_group=2
hdmi_mode=85

With this config, I see no issues with the troublesome monitor.

It's just bizzarre :-)

>
>> ---
>>   drivers/usb/eth/lan78xx.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/usb/eth/lan78xx.c b/drivers/usb/eth/lan78xx.c
>> index c5ff379..e8ee665 100644
>> --- a/drivers/usb/eth/lan78xx.c
>> +++ b/drivers/usb/eth/lan78xx.c
>> @@ -296,7 +296,7 @@ static int lan78xx_basic_reset(struct usb_device *udev,
>>          ret = lan7x_read_reg(udev, LAN78XX_USB_CFG0, &val);
>>          if (ret)
>>                  return ret;
>> -       val |= LAN78XX_USB_CFG0_BIR;
>> +       val &= ~LAN78XX_USB_CFG0_BIR;
>>          return lan7x_write_reg(udev, LAN78XX_USB_CFG0, val);
>>   }
>>
>> --
>> 1.8.3.1
>>
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