Re: [PATCH] ARM: exynos_defconfig: Enable DWC2 USB driver and USB ethernet gadget

[Krzysztof Kozlowski <k.kozlowski@samsung.com>]

On 26.08.2015 15:03, Marek Szyprowski wrote:
> Hello,
> 
> On 2015-08-26 05:43, Krzysztof Kozlowski wrote:
>> On 26.08.2015 10:58, Tyler Baker wrote:
>>> Hi Krzysztof,
>>>
>>> On 25 August 2015 at 18:44, Krzysztof Kozlowski
>>> <k.kozlowski@samsung.com> wrote:
>>>> On 26.08.2015 06:00, Tyler Baker wrote:
>>>>> Hi Marek/Krzysztof,
>>>>>
>>>>> On 18 August 2015 at 02:36, Krzysztof Kozlowski
>>>>> <k.kozlowski@samsung.com> wrote:
>>>>>> On 18.08.2015 18:15, Marek Szyprowski wrote:
>>>>>>> DWC2 (s3c-hsotg) hardware module is available on many Exynos
>>>>>>> based boards,
>>>>>>> so enable DWC2 driver as well as the most common USB Ethernet
>>>>>>> gadget.
>>>>>>>
>>>>>>> Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
>>>>> The kernelci.org bot recently reported a handful of exynos boot
>>>>> failures in next-20150825[1] only when using exynos_defconfig.
>>>> I noticed the issue too but I fought it was a temporary network
>>>> problem.
>>>> Apparently it's not temporary. :)
>>> I thought the same as well :)
>>>
>>>>> I went
>>>>> ahead and bisected[2] the failure and found this patch was the
>>>>> offender. Looking a bit closer, the kernelci.org boot tests typically
>>>>> pass ip=dhcp or ip=<ipaddr> as a kernel argument so that networking is
>>>>> setup by the kernel. These boot failures are due to the kernel network
>>>>> initialization timing out. Previously, in next-20150821[3] all the
>>>>> exynos platforms failing in next-20150825 initialized their network
>>>>> interfaces successfully, so this seems like a regression. Please have
>>>>> a closer look at the boot logs[4][5] for comparison. Kevin pointed out
>>>>> that  "asix 3-3.2.4:1.0 eth0: register 'asix' at
>>>>> usb-12110000.usb-3.2.4, ASIX AX88772 USB 2.0 Ethernet" is missing from
>>>>> the failed boot logs. Anyways, as a summary it looks like this change
>>>>> broke networking support on the arndale, arndale-octa, odroid xu3, and
>>>>> odroid x2.
>>>> I don't have such problem on my Odroid XU3 which also performs netboot
>>>> (Arch ARM Linux):
>>> Doh. I just realized the odroid-u3 is failing not the odroid-xu3,
>>> sorry for the confusion!
>>>
>>>> netboot=tftpboot 0x40008000 zImage; tftpboot 0x44000000
>>>> exynos5422-odroidxu3-lite.dtb; bootz 0x40008000 - 0x44000000
>>>>
>>>> TFTP from server 192.168.1.10; our IP address is 192.168.1.11
>>>>
>>>> [    0.000000] Kernel command line: console=tty1
>>>> console=ttySAC2,115200n8 root=/dev/mmcblk0p1 rootwait rw
>>>> no_console_suspend smsc95xx.macaddr=00:1e:06:61:7a:93
>>>>
>>>>
>>>> Do you have anything connected to USB ports of the devices?
>>> Nope, nothing connected to the USB ports in my lab.
>>>
>>>> For example on boot-exynos5250-arndale.html I see:
>>>> [    2.792934] using random self ethernet address
>>>> [    2.797209] using random host ethernet address
>>>> [    2.802244] usb0: HOST MAC 46:52:cf:b5:0f:e8
>>>> [    2.805923] usb0: MAC a2:04:5d:a6:2c:fa
>>>> [    2.809720] using random self ethernet address
>>>> [    2.814137] using random host ethernet address
>>>> [    2.818599] g_ether gadget: Ethernet Gadget, version: Memorial
>>>> Day 2008
>>>> [    2.825159] g_ether gadget: g_ether ready
>>>>
>>>> It looks like that's the difference.
>> Two issues seem strange to me:
>> 1. Why on these boards (except Odroid XU3) appears an usb0 interface
>> (after adding gadget support)? If they don't have the USB cable attached
>> then it shouldn't?
> 
> When USB Ethernet gadget is loaded it always creates usb0 network
> interface, regardless of the USB cable being attached or not.

Thanks for explaining.

> 
>> 2. ip=dhcp should send DCHP requests on all interfaces:
>>
>>     Otherwise the device is determined using
>>     autoconfiguration. This is done by sending
>>     autoconfiguration requests out of all devices,
>>     and using the device that received the first reply.
>>
>> So why it is not sent on eth0? Maybe there is no eth0 interface now
>> because of some conflict in USB drivers? Or maybe there was no eth0
>> interface also before and everything booted from MMC?
> 
> Maybe the names of network interfaces has changed or kernel parameters
> lacks specifying which network interface has to be configured (usb0 or
> eth0)?

The ip=dhcp should send requests on all interfaces. The eth0 (provided
by smsc95xx, @EHCI USB 12580000) should be there.

After comparing U3 boots I see that on broken boot the "exynos-ehci
12580000.ehci" starts earlier - around 2.17s. Detection of MMC happens
at 2.7s.

However on proper U3 boot, the 12580000.ehci probes around 15s. This
happens after MMC detection and after starting udev.

Tyler,
I don't know exactly how does your boot sequence look like. Maybe
netboot always failed and it booted from mmc? But clearly the change is
sensible and presence of usb0 interface should not fail the boot.

Best regards,
Krzysztof