Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755140Ab3JCSf3 (ORCPT ); Thu, 3 Oct 2013 14:35:29 -0400 Received: from mail-qa0-f54.google.com ([209.85.216.54]:51777 "EHLO mail-qa0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755109Ab3JCSfY (ORCPT ); Thu, 3 Oct 2013 14:35:24 -0400 MIME-Version: 1.0 In-Reply-To: <20131002172258.GC24791@phenom.dumpdata.com> References: <1380298207-29151-15-git-send-email-stefano.stabellini@eu.citrix.com> <20130930160223.GU3106@phenom.dumpdata.com> <20131002172258.GC24791@phenom.dumpdata.com> Date: Thu, 3 Oct 2013 13:35:22 -0500 Message-ID: Subject: Re: [PATCH v6 15/19] swiotlb-xen: call dma_capable only if dev->dma_mask is allocated From: Rob Herring To: Konrad Rzeszutek Wilk Cc: Stefano Stabellini , xen-devel@lists.xensource.com, Rob Herring , "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , Ian Campbell , Russell King - ARM Linux Content-Type: text/plain; charset=ISO-8859-1 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3725 Lines: 90 On Wed, Oct 2, 2013 at 12:22 PM, Konrad Rzeszutek Wilk wrote: > On Wed, Oct 02, 2013 at 06:13:35PM +0100, Stefano Stabellini wrote: >> The real issue is that some devices (xgmac, I am looking at you), don't >> set the dma_mask, even though they are perfectly capable of doing dma. > > So this looks like a bug in the drivers. I thought I saw a huge patchset > by the ARM maintainer that tries to fix the dma_mask and dma_mask_coherent > bugs? And also fix the drivers to use the dma mask? I think Russell only fixed incorrect handling of masks, not missing handling. >> >> Maybe I should modify the arm implementation of dma_capable (see >> http://marc.info/?l=linux-kernel&m=138029832007821&w=2) to ignore the >> dma_mask. > > Or fix the 'xgmac'? There's really some core changes needed to fix this and I'd guess there are lots of other cases of missing dma_mask. The problem is platform devices don't create a mask to assign to dma_mask in the first place. I think the right solution is assigning dma_mask to &coherent_dma_mask by default as Russell did for AMBA devices. I don't know if doing that would break anything or not. Rob >> >> On Mon, 30 Sep 2013, Konrad Rzeszutek Wilk wrote: >> > On Fri, Sep 27, 2013 at 05:10:03PM +0100, Stefano Stabellini wrote: >> > >> > Why? I am looking at X86 and IA64 and I see: >> > >> > 79 if (!dev->dma_mask) >> > 80 return 0; >> > >> > >> > Why not port dma_capable over to ARM? >> > >> > > Signed-off-by: Stefano Stabellini >> > > --- >> > > drivers/xen/swiotlb-xen.c | 6 +++--- >> > > 1 files changed, 3 insertions(+), 3 deletions(-) >> > > >> > > diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c >> > > index 790c2eb..3011736 100644 >> > > --- a/drivers/xen/swiotlb-xen.c >> > > +++ b/drivers/xen/swiotlb-xen.c >> > > @@ -512,7 +512,7 @@ dma_addr_t xen_swiotlb_map_page(struct device *dev, struct page *page, >> > > * buffering it. >> > > */ >> > > if (!xen_feature(XENFEAT_auto_translated_physmap) && >> > > - dma_capable(dev, dev_addr, size) && >> > > + dev->dma_mask && dma_capable(dev, dev_addr, size) && >> > > !range_straddles_page_boundary(phys, size) && !swiotlb_force) >> > > return dev_addr; >> > > >> > > @@ -532,7 +532,7 @@ dma_addr_t xen_swiotlb_map_page(struct device *dev, struct page *page, >> > > /* >> > > * Ensure that the address returned is DMA'ble >> > > */ >> > > - if (!dma_capable(dev, dev_addr, size)) { >> > > + if (dev->dma_mask && !dma_capable(dev, dev_addr, size)) { >> > > swiotlb_tbl_unmap_single(dev, map, size, dir); >> > > dev_addr = 0; >> > > } >> > > @@ -660,7 +660,7 @@ xen_swiotlb_map_sg_attrs(struct device *hwdev, struct scatterlist *sgl, >> > > >> > > if (swiotlb_force || >> > > xen_feature(XENFEAT_auto_translated_physmap) || >> > > - !dma_capable(hwdev, dev_addr, sg->length) || >> > > + (hwdev->dma_mask && !dma_capable(hwdev, dev_addr, sg->length)) || >> > > range_straddles_page_boundary(paddr, sg->length)) { >> > > /* >> > > * Pass the dma_addr of the first slab in the iotlb buffer as >> > > -- >> > > 1.7.2.5 >> > > >> > > > _______________________________________________ > linux-arm-kernel mailing list > linux-arm-kernel@lists.infradead.org > http://lists.infradead.org/mailman/listinfo/linux-arm-kernel -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/