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

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Date:   Wed, 18 Jan 2017 13:58:28 +0200
From:   Mathias Nyman <mathias.nyman@...ux.intel.com>
To:     Roger Quadros <rogerq@...com>,
        Alan Stern <stern@...land.harvard.edu>,
        gregkh@...uxfoundation.org
Cc:     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 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.

for patch 4/6:
Acked-by: Mathias Nyman <mathias.nyman@...ux.intel.com>

-Mathias