linux-kernel - Re: [PATCH v5 4/6] usb: xhci: use bus->sysdev for DMA configuration

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Date:   Thu, 19 Jan 2017 10:22:40 +0100
From:   Greg KH <gregkh@...uxfoundation.org>
To:     Mathias Nyman <mathias.nyman@...ux.intel.com>
Cc:     Roger Quadros <rogerq@...com>,
        Alan Stern <stern@...land.harvard.edu>,
        Sriram Dash <sriram.dash@....com>,
        linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org,
        mathias.nyman@...el.com, suresh.gupta@....com,
        felipe.balbi@...ux.intel.com, pku.leo@...il.com,
        Arnd Bergmann <arnd@...db.de>
Subject: Re: [PATCH v5 4/6] usb: xhci: use bus->sysdev for DMA configuration

On Wed, Jan 18, 2017 at 01:58:28PM +0200, Mathias Nyman wrote:
> On 12.01.2017 10:38, Roger Quadros wrote:
> > Mathias,
> > 
> > On 11/01/17 17:08, Alan Stern wrote:
> > > On Wed, 11 Jan 2017, Mathias Nyman wrote:
> > > 
> > > > On 17.11.2016 13:43, Sriram Dash wrote:
> > > > > From: Arnd Bergmann <arnd@...db.de>
> > > > > 
> > > > > For xhci-hcd platform device, all the DMA parameters are not
> > > > > configured properly, notably dma ops for dwc3 devices. So, set
> > > > > the dma for xhci from sysdev. sysdev is pointing to device that
> > > > > is known to the system firmware or hardware.
> > > > > 
> > > > > Signed-off-by: Arnd Bergmann <arnd@...db.de>
> > > > > Signed-off-by: Sriram Dash <sriram.dash@....com>
> > > > > Tested-by: Baolin Wang <baolin.wang@...aro.org>
> > > > > ---
> > > > 
> > > > ...
> > > > 
> > > > > +	/*
> > > > > +	 * sysdev must point to a device that is known to the system firmware
> > > > > +	 * or PCI hardware. We handle these three cases here:
> > > > > +	 * 1. xhci_plat comes from firmware
> > > > > +	 * 2. xhci_plat is child of a device from firmware (dwc3-plat)
> > > > > +	 * 3. xhci_plat is grandchild of a pci device (dwc3-pci)
> > > > > +	 */
> > > > > +	sysdev = &pdev->dev;
> > > > > +	if (sysdev->parent && !sysdev->of_node && sysdev->parent->of_node)
> > > > > +		sysdev = sysdev->parent;
> > > > > +#ifdef CONFIG_PCI
> > > > > +	else if (sysdev->parent && sysdev->parent->parent &&
> > > > > +		 sysdev->parent->parent->bus == &pci_bus_type)
> > > > > +		sysdev = sysdev->parent->parent;
> > > > > +#endif
> > > > > +
> > > > 
> > > > Not maybe the the ideal situation here, and looks really tailored to make PCI dwc3
> > > > controllers with xhci support work.
> > > > 
> > > > Was there some reason child devices can't automatically inherit the dma mask from the parents,
> > > > forcing us to dig it from grandparents?
> > > > 
> > > > Anyway, looks like the dwc3 part is already in 4.10-rc,
> > > > If Greg and Alan want to take this series that's fine by me
> > > 
> > > I have no objections.
> > > 
> > > Alan Stern
> > > 
> > > > I haven't tested that it won't break anything on PCI XHCI controllers though
> > > > 
> > > > -Mathias
> > 
> > Are you going to pick all the remaining patches from this series (i.e. 1 to 4)?
> > 
> > That should fix the warning that people are seeing on v4.10-rc.
> > 
> 
> Let's check with Greg
> 
> Greg, 5/6 and 6/6 are in 4.10-rc already, causing additional warnings for
> people using dwc3 xhci.
> 
> First 3 patches change usb core,  patch 4 xhci.
> 
> Compiles and boots, doesn't break pci xhci (non-dwc3) functionality
> 
> Would you like me to send first 4 patches for usb-linus to get a clean final 4.10
> without warnings, or to send them for usb-next?
> 
> Or will you just pick the patches from here directly.

I don't have them "here" anymore, they are long-gone from my patch
queue, sorry.

Can you resend them, I don't know what these patches contained, but if
they fix an 4.10 issue, that would be good to have there, right?

thanks,

greg k-h