Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752526AbaDYKNg (ORCPT ); Fri, 25 Apr 2014 06:13:36 -0400 Received: from mail-qg0-f46.google.com ([209.85.192.46]:58360 "EHLO mail-qg0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752431AbaDYKNc (ORCPT ); Fri, 25 Apr 2014 06:13:32 -0400 MIME-Version: 1.0 In-Reply-To: <201404221552.00501.arnd@arndb.de> References: <1397824031-4892-1-git-send-email-lftan@altera.com> <1397845149-3141-1-git-send-email-lftan@altera.com> <1397845149-3141-4-git-send-email-lftan@altera.com> <201404221552.00501.arnd@arndb.de> Date: Fri, 25 Apr 2014 18:13:31 +0800 X-Google-Sender-Auth: cnSv5t4lUrPoG1A-Wk7n_3nNVao Message-ID: Subject: Re: [PATCH 14/28] nios2: DMA mapping API From: Ley Foon Tan To: Arnd Bergmann Cc: Linux-Arch , "linux-kernel@vger.kernel.org" , "linux-doc@vger.kernel.org" , cltang@codesourcery.com Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Apr 22, 2014 at 9:52 PM, Arnd Bergmann wrote: > On Friday 18 April 2014, Ley Foon Tan wrote: > >> +static inline int dma_supported(struct device *dev, u64 mask) >> +{ >> + /* we fall back to GFP_DMA when the mask isn't all 1s, >> + * so we can't guarantee allocations that must be >> + * within a tighter range than GFP_DMA. >> + */ >> + if (mask < 0x00ffffff) >> + return 0; >> + >> + return 1; >> +} > >> +void *dma_alloc_coherent(struct device *dev, size_t size, >> + dma_addr_t *dma_handle, gfp_t gfp) >> +{ >> + void *ret; >> + >> + /* ignore region specifiers */ >> + gfp &= ~(__GFP_DMA | __GFP_HIGHMEM); >> + >> + /* optimized page clearing */ >> + gfp |= __GFP_ZERO; >> + >> + if (dev == NULL || (dev->coherent_dma_mask < 0xffffffff)) >> + gfp |= GFP_DMA; > > What is the significance of ZONE_DMA on this architecture? > > Do you actually have DMA masters with a 0x00ffffff mask? Actually, nios2 doesn't have DMA master with 0x00ffffff mask. I will change it to return 1, same as some other architectures implementation. And the ZONE_DMA stuff will remove as well, it shouldn't have ZONE_DMA limitation. -- 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/