From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752958AbcD0OPC (ORCPT ); Wed, 27 Apr 2016 10:15:02 -0400 Received: from arroyo.ext.ti.com ([192.94.94.40]:45058 "EHLO arroyo.ext.ti.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752492AbcD0OPA (ORCPT ); Wed, 27 Apr 2016 10:15:00 -0400 Subject: Re: [PATCH] usb: dwc3: host: inherit dma configuration from parent dev To: Catalin Marinas , Felipe Balbi References: <1461612094-30939-1-git-send-email-grygorii.strashko@ti.com> <87d1pcrj0t.fsf@intel.com> <571F2357.9080509@ti.com> <878tzzpq19.fsf@intel.com> <20160427135859.GC20646@e104818-lin.cambridge.arm.com> CC: Greg Kroah-Hartman , Yoshihiro Shimoda , , Sekhar Nori , , David Fisher , "Thang Q. Nguyen" , , Arnd Bergmann From: Grygorii Strashko Message-ID: <5720C934.20106@ti.com> Date: Wed, 27 Apr 2016 17:14:12 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.6.0 MIME-Version: 1.0 In-Reply-To: <20160427135859.GC20646@e104818-lin.cambridge.arm.com> Content-Type: text/plain; charset="windows-1252"; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/27/2016 04:59 PM, Catalin Marinas wrote: > On Wed, Apr 27, 2016 at 08:41:06AM +0300, Felipe Balbi wrote: >> Grygorii Strashko writes: >>> On 04/26/2016 09:17 AM, Felipe Balbi wrote: >>>> Grygorii Strashko writes: >>>>> Now not all DMA paremters configured properly for "xhci-hcd" platform >>>>> device which is created manually. For example: dma_pfn_offset, dam_ops >>>>> and iommu configuration will not corresponds "dwc3" devices >>>>> configuration. As result, this will cause problems like wrong DMA >>>>> addresses translation on platforms with LPAE enabled like Keystone 2. >>>>> >>>>> When platform is using DT boot mode the DMA configuration will be >>>>> parsed and applied from DT, so, to fix this issue, reuse >>>>> of_dma_configure() API and retrieve DMA configuartion for "xhci-hcd" >>>>> from DWC3 device node. >>>> >>>> patch is incomplete. You left out non-DT users which might suffer from >>>> the same problem. >>> >>> Honestly, I don't know how to fix it gracefully for non-DT case. >>> I can update commit message to mention that this is fix for DT case only. >> >> no, that won't do :-) There are other users for this driver and they are >> all "out-of-compliance" when it comes to DMA usage. Apparently, the >> desired behavior is to pass correct device to DMA API which the gadget >> side is already doing (see below). For the host side, the fix has to be >> more involved. >> >> Frankly, I'd prefer that DMA setup could be inherited from parent >> device, then it wouldn't really matter and a bunch of this could be >> simplified. Some sort of dma_inherit(struct device *dev, struct device >> *parent) would go a long way, IMHO. > > I would be in favour of a dma_inherit() function as well. We could hack > something up in the arch code (like below) but I would rather prefer an > explicit dma_inherit() call by drivers creating such devices. > > diff --git a/arch/arm64/include/asm/dma-mapping.h b/arch/arm64/include/asm/dma-mapping.h > index ba437f090a74..ea6fb9b0e8fa 100644 > --- a/arch/arm64/include/asm/dma-mapping.h > +++ b/arch/arm64/include/asm/dma-mapping.h > @@ -29,8 +29,11 @@ extern struct dma_map_ops dummy_dma_ops; > > static inline struct dma_map_ops *__generic_dma_ops(struct device *dev) > { > - if (dev && dev->archdata.dma_ops) > - return dev->archdata.dma_ops; > + while (dev) { > + if (dev->archdata.dma_ops) > + return dev->archdata.dma_ops; > + dev = dev->parent; > + } > > /* > * We expect no ISA devices, and all other DMA masters are expected to > It's no enough to W/A just dma_ops :( dma_inherit()... FYI: http://www.spinics.net/lists/arm-kernel/msg384012.html Maybe you'll be able to find the way to make it acceptable. -- regards, -grygorii