From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-x234.google.com (mail-pa0-x234.google.com [IPv6:2607:f8b0:400e:c03::234]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id CE4831A03C0 for ; Tue, 27 Oct 2015 17:02:26 +1100 (AEDT) Received: by pacfv9 with SMTP id fv9so221262561pac.3 for ; Mon, 26 Oct 2015 23:02:25 -0700 (PDT) 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 MIME-Version: 1.0 In-Reply-To: <20151023205718.GC10197@linux.vnet.ibm.com> Content-Type: text/plain; charset=koi8-r; format=flowed List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , 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