From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753871AbbJ0GC1 (ORCPT ); Tue, 27 Oct 2015 02:02:27 -0400 Received: from mail-pa0-f45.google.com ([209.85.220.45]:35936 "EHLO mail-pa0-f45.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751572AbbJ0GCZ (ORCPT ); Tue, 27 Oct 2015 02:02:25 -0400 Subject: Re: [PATCH 2/7 v2] powerpc/dma-mapping: override dma_get_page_shift To: Nishanth Aravamudan , Michael Ellerman References: <20151023205420.GA10197@linux.vnet.ibm.com> <20151023205718.GC10197@linux.vnet.ibm.com> Cc: Matthew Wilcox , Keith Busch , Benjamin Herrenschmidt , Paul Mackerras , David Gibson , Christoph Hellwig , "David S. Miller" , linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, sparclinux@vger.kernel.org From: Alexey Kardashevskiy Message-ID: <562F1368.1030204@ozlabs.ru> Date: Tue, 27 Oct 2015 17:02:16 +1100 User-Agent: Mozilla/5.0 (X11; Linux i686 on x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 MIME-Version: 1.0 In-Reply-To: <20151023205718.GC10197@linux.vnet.ibm.com> Content-Type: text/plain; charset=koi8-r; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 10/24/2015 07:57 AM, Nishanth Aravamudan wrote: > On Power, the kernel's page size can differ from the IOMMU's page size, > so we need to override the generic implementation, which always returns > the kernel's page size. Lookup the IOMMU's page size from struct > iommu_table, if available. Fallback to the kernel's page size, > otherwise. > > Signed-off-by: Nishanth Aravamudan > --- > arch/powerpc/include/asm/dma-mapping.h | 3 +++ > arch/powerpc/kernel/dma.c | 9 +++++++++ > 2 files changed, 12 insertions(+) > > diff --git a/arch/powerpc/include/asm/dma-mapping.h b/arch/powerpc/include/asm/dma-mapping.h > index 7f522c0..c5638f4 100644 > --- a/arch/powerpc/include/asm/dma-mapping.h > +++ b/arch/powerpc/include/asm/dma-mapping.h > @@ -125,6 +125,9 @@ static inline void set_dma_offset(struct device *dev, dma_addr_t off) > #define HAVE_ARCH_DMA_SET_MASK 1 > extern int dma_set_mask(struct device *dev, u64 dma_mask); > > +#define HAVE_ARCH_DMA_GET_PAGE_SHIFT 1 > +extern unsigned long dma_get_page_shift(struct device *dev); > + > #include > > extern int __dma_set_mask(struct device *dev, u64 dma_mask); > diff --git a/arch/powerpc/kernel/dma.c b/arch/powerpc/kernel/dma.c > index 59503ed..e805af2 100644 > --- a/arch/powerpc/kernel/dma.c > +++ b/arch/powerpc/kernel/dma.c > @@ -335,6 +335,15 @@ int dma_set_mask(struct device *dev, u64 dma_mask) > } > EXPORT_SYMBOL(dma_set_mask); > > +unsigned long dma_get_page_shift(struct device *dev) > +{ > + struct iommu_table *tbl = get_iommu_table_base(dev); > + if (tbl) > + return tbl->it_page_shift; All PCI devices have this initialized on POWER (at least, our, IBM's POWER) so 4K will always be returned here while in the case of (get_dma_ops(dev)==&dma_direct_ops) it could actually return PAGE_SHIFT. Is 4K still preferred value to return here? > + return PAGE_SHIFT; > +} > +EXPORT_SYMBOL(dma_get_page_shift); > + > u64 __dma_get_required_mask(struct device *dev) > { > struct dma_map_ops *dma_ops = get_dma_ops(dev); > -- Alexey