PROBLEM: DWC3 USB 3.0 not working on Odroid-XU4 with Exynos 5422

[Vivek Gautam]

Hi Michael,


On Tue, Oct 4, 2016 at 4:28 PM, Michael Niewöhner <linux at mniewoehner.de> wrote:

> > > > > > [1.] One line summary of the problem:
> > > > > > DWC3 USB 3.0 not working on Odroid-XU4 with Exynos 5422
> > > > > >
> > > > > > [2.] Full description of the problem/report:
> > > > > > No usb 3.0 devices are being detected when attached while USB 2.0
> > > > > > devices work on the same port.
> > > > > > USB 3.0 works after applying patches [9.1] and [9.2], but seems
> > > > > > to be
> > > > > > buggy. The usb hub is redetected every time an usb device is
> > > > > > attached.

[snip]

>> > > > > > [9.] Other notes, patches, fixes, workarounds:
>> > > > > > [9.1] https://lkml.org/lkml/2014/4/28/234
>> > > > > > [9.2] https://lkml.org/lkml/2015/2/2/259
>>
>> These patches are required to get USB super-speed working on Exynos5420/5800.
>> But they did not make to upstream. There was resistance on adding new
>> phy_calibrate()
>> callback.
>>
>> Without these patches the Exynos5420/5800 will enumerate all
>> super-speed capable devices
>> as high-speed devices.
>> Last time we checked with exynos542x smdk boards and peach-* boards,
>> we could get the
>> Super - speed devices working. I have not tested odroid anytime so
>> don't have much idea about the
>> its intricacies.
>> I guess Anand was able to use these patches to get his kernel working in past.
>
>
> The patches don't work anymore with 4.8-rc* / 4.8. They worked - but very
> unstable - with 4.7.
>
> One more problem appeared since one of the 4.8-RCs: reboot hangs when the dwc3
> module is loaded. If I unload it before reboot / shutdown everything is fine.
>
>
>>
>> When you have a downstream on-board usb hub, ideally it should be able
>> to detect the devices
>> and not reset everytime you connect a new device (like you mentioned earlier).
>> There can be two possible reasons why the hub keeps getting reset ever
>> after applying the above
>> mentioned patches:
>> 1) the clock rates are not proper.
>> 2) the regulator load setting is not enough to drive the hub.
>>
>> Anand, can you please point Michael to an older kernel with which you
>> could test usb on odroid successfully ?
>> You can compare the clocks with an older version and see if there'a
>> any difference.
>>
>> Any possibility of any other framework (such as, bus-freq) trimming
>> down the clock - rates ?
>
>
> ################################
> # v4.7.5
> ################################
>
> $ cat /sys/kernel/debug/clk/clk_summary | grep usb
>  sclk_usbh20_scan_clk                     0            0   480000000          0
>  sclk_usbh20                              0            0    48000
> 000          0
>     mout_usbd300                          1            1    24000000          0
>        dout_usbd300                       0            0    24000000          0
>           sclk_usbd300
>                  0            0    24000000          0
>        dout_usbphy300                     1            1    24000000          0
>           sclk_usbphy300                  4            4    24000
> 000          0
>     mout_usbd301                          1            1    24000000          0
>        dout_usbd301                       0            0    24000000          0
>           sclk_usbd301
>                  0            0    24000000          0
>        dout_usbphy301                     1            1    24000000          0
>           sclk_usbphy301                  3            3    24000
> 000          0
>                          usbd301           1            1   100000000
>                          usbd300           1            1   100000000
>
> usbh20           3            3   100000000          0

>
> ################################
> # v4.8.0
> ################################
>
> $ cat /sys/kernel/debug/clk/clk_summary | grep usb
>  sclk_usbh20_scan_clk                     0            0   480000000          0
>  sclk_usbh20                              0            0    48000000
>         0
>     mout_usbd300                          1            1    24000000          0
>        dout_usbd300                       0            0    24000000          0
>           sclk_usbd300
>             0            0    24000000          0
>        dout_usbphy300                     1            1    24000000          0
>           sclk_usbphy300                  4            4    24000000
>         0
>     mout_usbd301                          1            1    24000000          0
>        dout_usbd301                       0            0    24000000          0
>           sclk_usbd301
>             0            0    24000000          0
>        dout_usbphy301                     1            1    24000000          0
>           sclk_usbphy301                  3            3    24000000
>         0
>                          usbd301           1            1   100000000

This clock should have been 200MHz.

>                          usbd300           1            1   100000000
>                          usbh2
> 0           3            3   100000000          0
>
> $ cat /sys/kernel/debug/usb/devices
> <<system hangs>>
>

The clocks are same across working/non-working.
Is it possible to bisect the commit that's causing hang for 4.8x ?

Adding few of the folks from Samsung who can test dwc3 usb on smdk/peach boards.
+Alim, Pankaj

Hi Alim, Pankaj,
can you please give a try with 4.8 kernel on peach/smdk542x board and
see if dwc3 usb works or not.
You may need to the patches mentioned in [9.1] and [9.2] mentioned above.


[snip]


Thanks
Vivek

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