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

From: Mathias Nyman
Date: Thu Jan 19 2017 - 06:36:15 EST


On 19.01.2017 11:22, Greg KH wrote:
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@xxxxxxxx>

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@xxxxxxxx>
Signed-off-by: Sriram Dash <sriram.dash@xxxxxxx>
Tested-by: Baolin Wang <baolin.wang@xxxxxxxxxx>
---

...

+ /*
+ * 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?


Right, I'll send them

-Mathias