Hi,

Greg KH <gre...@linuxfoundation.org> writes:
> On Fri, Jan 20, 2017 at 01:35:39PM +0200, Mathias Nyman wrote:
>> On 20.01.2017 12:22, Greg KH wrote:
>> > On Fri, Jan 20, 2017 at 11:23:36AM +0200, Mathias Nyman wrote:
>> > > On 19.01.2017 20:48, Greg KH wrote:
>> > > > On Thu, Jan 19, 2017 at 02:21:26PM +0200, Mathias Nyman wrote:
>> > > > > Hi Greg
>> > > > > 
>> > > > > This series by Arnd Bergmann was originally six patches, but last 
>> > > > > two of
>> > > > > them were already taken to 4.10. Without the rest of them there will
>> > > > > be a regression in 4.10.
>> > > > 
>> > > > Is it really a regression?  I thought this had never worked before in
>> > > > older kernels, right?
>> > > > 
>> > > 
>> > > Regression when xhci hosts in dwc3 controllers are used.
>> > 
>> > So that worked in 4.9?
>> > 
>> > > For example patch 5/6 removed setting dma mask for xhci in dwc3 host 
>> > > init:
>> > > 
>> > > +++ b/drivers/usb/dwc3/host.c
>> > > @@ -84,11 +84,7 @@ int dwc3_host_init(struct dwc3 *dwc)
>> > >                  return -ENOMEM;
>> > >          }
>> > > -        dma_set_coherent_mask(&xhci->dev, dwc->dev->coherent_dma_mask);
>> > > -
>> > >          xhci->dev.parent        = dwc->dev;
>> > > -        xhci->dev.dma_mask      = dwc->dev->dma_mask;
>> > > -        xhci->dev.dma_parms     = dwc->dev->dma_parms;
>> > > 
>> > > So now xhci platform driver prints a scary warning because of the 
>> > > missing dma mask:
>> > > 
>> > > static int xhci_plat_probe(struct platform_device *pdev)
>> > >   /* Try to set 64-bit DMA first */
>> > >  if (WARN_ON(!pdev->dev.dma_mask))
>> > >                  /* Platform did not initialize dma_mask */
>> > >                  ret = dma_coerce_mask_and_coherent(&pdev->dev,
>> > >                                                     DMA_BIT_MASK(64));
>> > >          else
>> > >  ...
>> > > This is fixed in the first 4 patches.
>> > > 
>> > > There might be other other issues as well caused by having only the dwc3
>> > > changed applied of this series, but not the core and xhci parts
>> > 
>> > Should we just fix the "scary warning" instead, by removing it?  :)
>> > 
>> > I say all of this because this seems like some very big changes so late
>> > in the -rc cycle.
>> > 
>> 
>> I guess that would work, or at least get us to the same stage as 4.9.
>> I'll send a patch for it.
>
> Great.
>
>> Gives more time to look at the usb core changes. I'm not really
>> myself running or testing the dwc3 host side.
>
> Me either.  Any hints on some hardware that would allow me to do that?

Intel Edison. Or any recent TI board (AM437x SK, for instance). Google
Pixel Phone (but good luck running a mainline kernel there ;-)

-- 
balbi

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