linux-kernel - Re: [PATCH v3 2/2] usb:dwc3: pass arch data to xhci-hcd child

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Date:	Fri, 1 Apr 2016 12:46:32 +0300
From:	Grygorii Strashko <grygorii.strashko@...com>
To:	Felipe Balbi <felipe.balbi@...ux.intel.com>,
	"Thang Q. Nguyen" <tqnguyen@....com>
CC:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	<linux-usb@...r.kernel.org>, <linux-omap@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, <linux-arm@...ts.infradead.org>,
	Arnd Bergmann <arnd@...db.de>,
	"Karicheri, Muralidharan" <m-karicheri2@...com>,
	Peter Ujfalusi <peter.ujfalusi@...com>, Phong Vo <pvo@....com>,
	Loc Ho <lho@....com>, patches <patches@....com>,
	Santosh Shilimkar <ssantosh@...nel.org>,
	"Ben Dooks (embedded platforms)" <ben-linux@...ff.org>
Subject: Re: [PATCH v3 2/2] usb:dwc3: pass arch data to xhci-hcd child

On 04/01/2016 10:58 AM, Felipe Balbi wrote:
> 
> Hi,
> 
> Grygorii Strashko <grygorii.strashko@...com> writes:
>> On 03/31/2016 11:04 AM, Felipe Balbi wrote:
>>> "Thang Q. Nguyen" <tqnguyen@....com> writes:
>>>> [ text/plain ]
>>>> Thanks Grygorii for information.
>>>> I checked but do not see dma_init_dev_from_parent is used in
>>>> linux-next repository. Can you give me more information for what
>>>> branch I can checkout to use it for USB DWC3?
>>>
>>> dma_init_dev_from_parent() is still a proposal ;-)
>>>
>>
>> Felipe,
>>
>> After some experiments I came up with below fix (not common, but fixes USB
>> case on keystone 2). if you agree with proposed fix I'll send proper
>> patches to fix usb_add_gadget_udc_release() and dwc3_host_init() in the same
>> way.
>>
>> diff --git a/drivers/usb/dwc3/host.c b/drivers/usb/dwc3/host.c
>> index c679f63..3fe1c65 100644
>> --- a/drivers/usb/dwc3/host.c
>> +++ b/drivers/usb/dwc3/host.c
>> @@ -17,6 +17,7 @@
>>   
>>   #include <linux/platform_device.h>
>>   #include <linux/usb/xhci_pdriver.h>
>> +#include <linux/of_device.h>
>>   
>>   #include "core.h"
>>   
>> @@ -35,8 +36,6 @@ int dwc3_host_init(struct dwc3 *dwc)
>>          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;
>>   
>>          dwc->xhci = xhci;
>>   
>> @@ -62,6 +61,12 @@ int dwc3_host_init(struct dwc3 *dwc)
>>          phy_create_lookup(dwc->usb3_generic_phy, "usb3-phy",
>>                            dev_name(&xhci->dev));
>>   
>> +       if (!dwc->dev->of_node) {
>> +               xhci->dev.dma_mask      = dwc->dev->dma_mask;
>> +               xhci->dev.dma_parms     = dwc->dev->dma_parms;
>> +       } else
>> +               of_dma_configure(&xhci->dev, dwc->dev->of_node);
> 
> if of_dma_configure() does what you want, why don't you just stick it in
> dwc3-keystone.c and let the driver continue to copy things for now ?
> Something like below, perhaps ?
> 

I know (and i have patch to fix that which I'm going to send) that DMA config 
 in dwc3-keystone.c is not correct and we are good till now just 
because dwc3_keystone is not used for DMA operations directly.

Now about xhci and friends:
dwc3_keystone *is created* from DT : of_platform_device_create() -> of_platform_device_create_pdata() -> of_dma_configure()
|- dwc3 *is created* from DT : of_platform_device_create() -> of_platform_device_create_pdata() -> of_dma_configure()
   |- [1] *creates* xhci dev manually : DMA configuration copied manually in dwc3_host_init()
   |- [2] *creates* usb_gadget dev manually: DMA configuration copied manually in usb_add_gadget_udc_release()
   |- *creates* usb_udc dev manually : not used for DMA operations directly (as I've checked)

Now cases [1] & [2] introduces failures, because DMA configuration is not complete for
these devices.

I can confirm that if I fix [1] & [2] as above USB Device/Dual modes will start 
working on K2E.

-- 
regards,
-grygorii