No Ethernet on Raspberry Pi 3 in v4.13-rc1

[Stefan Wahren]

> Robin Murphy <robin.murphy at arm.com> hat am 25. Juli 2017 um 15:21 geschrieben:
> 
> 
> Hi Stefan,
> 
> On 25/07/17 06:19, Stefan Wahren wrote:
> >>> With arm64 4.13-rc1 I get no eth0 device on Pi3 (openSUSE Tumbleweed).
> >>> The v4.13-rc1 DT works okay with a 4.12 kernel.
> >>>
> >>> Possibly related:
> >>>
> >>> [   15.916350] OF: /soc/usb at 7e980000: could not get #phy-cells for /phy
> >>>
> >>> [   16.496662] usb 1-1: new high-speed USB device number 2 using dwc2
> >>> [   16.502988] dwc2 3f980000.usb: Cannot do DMA to address
> >>> 0x00000000335da400
> >>
> >> This is from SWIOTLB's map_single(), which means whatever device was
> >> passed into dma_map_single() when mapping the URB had a DMA mask smaller
> >> than 30 bits (or none at all), which sounds wrong and is almost
> >> certainly the root of the problem (i.e. it probably wasn't the actual
> >> HCD device described in DT and set up by of_dma_configure()). 
> > 
> > how can i figure out what's cause this issue (bcm283x or dwc2 specific)?
> > 
> > The dwc2 hcd already check the DMA mask on probe [1] and i never saw a warning in error case.
> 
> I'll admit I'm a little stumped, since the two commits to dwc2 since
> 4.12 seem entirely inconsequential.
> 
> The only way I can see this happening is if the first dma_capable()
> check in swiotlb_map_page() fails, and since swiotlb_force must be set
> to SWIOTLB_NOFORCE in order to print the error later, and the address
> and size look reasonable, that only leaves dev->dma_mask as the culprit.
> 
> From the subsequent fallout (which on closer inspection looks more to do
> with calling into uninitialised SWIOTLB state than the arm64 DMA code
> actually doing anything wrong), I'd guess dev->dma_pfn_offset is
> probably 0 as well, which further points to the wrong device. Maybe
> something's changed lower down in the USB core? Turning on tracing and
> booting with "tp_printk trace_event=swiotlb_bounced" on the command line
> should shed a bit more light on what's going on.
> 

FWIW, i added some dev_info before and after dma_set_mask in dwc2 (error case):

[    5.471761] dwc2 3f980000.usb: before mask: FFFFFFFF
[    5.491016] dwc2 3f980000.usb: before coherent mask: FFFFFFFF
[    5.513379] dwc2 3f980000.usb: after mask: FFFFFFFF
[    5.532572] dwc2 3f980000.usb: after coherent mask: FFFFFFFF
[    5.555039] dwc2 3f980000.usb: DWC OTG Controller
[    5.575855] dwc2 3f980000.usb: new USB bus registered, assigned bus number 1
[    5.605944] dwc2 3f980000.usb: irq 41, io mem 0x3f980000

which doesn't match the tracing outputs.

> Robin.
> 
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