From mboxrd@z Thu Jan 1 00:00:00 1970 From: david.vrabel@citrix.com (David Vrabel) Date: Tue, 14 Oct 2014 17:12:12 +0100 Subject: [PATCH v4 6/7] xen/arm/arm64: introduce xen_arch_need_swiotlb In-Reply-To: <20141014160352.GF30965@laptop.dumpdata.com> References: <1412941908-5850-6-git-send-email-stefano.stabellini@eu.citrix.com> <20141014160352.GF30965@laptop.dumpdata.com> Message-ID: <543D4B5C.2040502@citrix.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On 14/10/14 17:03, Konrad Rzeszutek Wilk wrote: > On Fri, Oct 10, 2014 at 12:51:47PM +0100, Stefano Stabellini wrote: >> Introduce an arch specific function to find out whether a particular dma >> mapping operation needs to bounce on the swiotlb buffer. >> >> On ARM and ARM64, if the page involved is a foreign page and the device >> is not coherent, we need to bounce because at unmap time we cannot >> execute any required cache maintenance operations (we don't know how to >> find the pfn from the mfn). ... >> --- a/arch/x86/include/asm/xen/page.h >> +++ b/arch/x86/include/asm/xen/page.h >> @@ -236,4 +236,11 @@ void make_lowmem_page_readwrite(void *vaddr); >> #define xen_remap(cookie, size) ioremap((cookie), (size)); >> #define xen_unmap(cookie) iounmap((cookie)) >> >> +static inline bool xen_arch_need_swiotlb(struct device *dev, >> + unsigned long pfn, >> + unsigned long mfn) >> +{ >> + return false; >> +} > > Why not make this an macro? Because macros are evil and inline functions are preferred. David