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

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Message-ID: <0a1a4328-fea3-a7fb-2c1b-15dbf77053b6@ti.com>
Date:   Thu, 12 Jan 2017 10:38:30 +0200
From:   Roger Quadros <rogerq@...com>
To:     Alan Stern <stern@...land.harvard.edu>,
        Mathias Nyman <mathias.nyman@...ux.intel.com>
CC:     Sriram Dash <sriram.dash@....com>, <linux-kernel@...r.kernel.org>,
        <linux-usb@...r.kernel.org>, <mathias.nyman@...el.com>,
        <gregkh@...uxfoundation.org>, <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

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.

cheers,
roger