From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754991AbcDDQMk (ORCPT ); Mon, 4 Apr 2016 12:12:40 -0400 Received: from userp1040.oracle.com ([156.151.31.81]:30737 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751495AbcDDQMi (ORCPT ); Mon, 4 Apr 2016 12:12:38 -0400 Subject: Re: [PATCH v3 2/2] usb:dwc3: pass arch data to xhci-hcd child To: Felipe Balbi , Grygorii Strashko , "Thang Q. Nguyen" References: <1457594332-7490-1-git-send-email-tqnguyen@apm.com> <1457594332-7490-3-git-send-email-tqnguyen@apm.com> <87mvpgi02f.fsf@intel.com> <56FBDA0D.4030507@ti.com> <87egashxz8.fsf@intel.com> <87k2kjgjjf.fsf@intel.com> <56FD3D2F.8070501@ti.com> <871t6pahg8.fsf@intel.com> <56FE4378.3030205@ti.com> <87shz58wbw.fsf@intel.com> <56FE54DB.5000201@ti.com> <878u0x8ru4.fsf@intel.com> <56FEBAC1.2040509@oracle.com> <87oa9p7url.fsf@intel.com> Cc: Greg Kroah-Hartman , linux-usb@vger.kernel.org, linux-omap@vger.kernel.org, linux-kernel@vger.kernel.org, linux-arm@lists.infradead.org, Arnd Bergmann , "Karicheri, Muralidharan" , Peter Ujfalusi , Phong Vo , Loc Ho , patches , Santosh Shilimkar , "Ben Dooks (embedded platforms)" , Russell King From: santosh shilimkar Organization: Oracle Corporation Message-ID: <57029232.1080103@oracle.com> Date: Mon, 4 Apr 2016 09:11:30 -0700 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:38.0) Gecko/20100101 Thunderbird/38.5.1 MIME-Version: 1.0 In-Reply-To: <87oa9p7url.fsf@intel.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit X-Source-IP: aserv0022.oracle.com [141.146.126.234] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 4/3/2016 11:28 PM, Felipe Balbi wrote: > santosh shilimkar writes: >> +Arnd, RMK, >> >> On 4/1/2016 4:57 AM, Felipe Balbi wrote: >>> >>> Hi, >>> >>> Grygorii Strashko writes: >>>> On 04/01/2016 01:20 PM, Felipe Balbi wrote: >> >> [...] >> >>>> commit 7ace8fc8219e4cbbfd5b4790390d9a01a2541cdf >>>> Author: Yoshihiro Shimoda >>>> Date: Mon Jul 13 18:10:05 2015 +0900 >>>> >>>> usb: gadget: udc: core: Fix argument of dma_map_single for IOMMU >>>> >>>> The dma_map_single and dma_unmap_single should set "gadget->dev.parent" >>>> instead of "&gadget->dev" in the first argument because the parent has >>>> a udc controller's device pointer. >>>> Otherwise, iommu functions are not called in ARM environment. >>>> >>>> Signed-off-by: Yoshihiro Shimoda >>>> Signed-off-by: Felipe Balbi >>>> >>>> Above actually means that DMA configuration code can be dropped from >>>> usb_add_gadget_udc_release() completely. Right?: >>> >>> true, but now I'm not sure what's better: copy all necessary bits from >>> parent or just pass the parent device to all DMA API. >>> >>> Anybody to shed a light here ? >>> >> The expectation is drivers should pass the proper dev pointers and let >> core DMA code deal with it since it knows the per device dma properties. > > okay, so how do you get proper DMA pointers with something like this: > > kdwc3_dma_mask = dma_get_mask(dev); > dev->dma_mask = &kdwc3_dma_mask; > > This doesn't anything. > Drivers actually needs to touch dma_mask(s) only if the core DMA code hasn't populated it it. I see Grygorii pointed out couple of things already. Reagrds, Santosh