Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932076Ab3HAWWn (ORCPT ); Thu, 1 Aug 2013 18:22:43 -0400 Received: from caramon.arm.linux.org.uk ([78.32.30.218]:39851 "EHLO caramon.arm.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753572Ab3HAWWl (ORCPT ); Thu, 1 Aug 2013 18:22:41 -0400 In-Reply-To: <20130801213420.GL23006@n2100.arm.linux.org.uk> References: <20130801213420.GL23006@n2100.arm.linux.org.uk> From: Santosh Shilimkar To: linux-arm-kernel@lists.infradead.org Cc: linux-kernel@vger.kernel.org, Arnd Bergmann , Jens Axboe Subject: [PATCH RFC 48/51] ARM: 7795/1: mm: dma-mapping: Add dma_max_pfn(dev) helper function Message-Id: Date: Thu, 01 Aug 2013 23:22:14 +0100 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1822 Lines: 48 Most of the kernel assumes that PFN0 is the start of the physical memory (RAM). This assumptions is not true on most of the ARM SOCs and hence and if one try to update the ARM port to follow the assumptions, we end of breaking the dma bounce limit for few block layer drivers. One such example is trying to unify the meaning of max*_pfn on ARM as the bootmem layer expects, breaks few block layer driver dma bounce limit. To fix this problem, we introduce dma_max_pfn(dev) generic helper with a possibility of override from the architecture code. The helper converts a DMA bitmask of bits to a block PFN number. In all the generic cases, it is just "dev->dma_mask >> PAGE_SHIFT" and hence default behavior is maintained as is. Subsequent patches will make use of the helper. No functional change. Signed-off-by: Santosh Shilimkar Signed-off-by: Russell King --- include/linux/dma-mapping.h | 7 +++++++ 1 files changed, 7 insertions(+), 0 deletions(-) diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h index 48ef6f5..4ce089e 100644 --- a/include/linux/dma-mapping.h +++ b/include/linux/dma-mapping.h @@ -153,6 +153,13 @@ static inline int dma_set_seg_boundary(struct device *dev, unsigned long mask) return -EIO; } +#ifndef dma_max_pfn +static inline unsigned long dma_max_pfn(struct device *dev) +{ + return *dev->dma_mask >> PAGE_SHIFT; +} +#endif + static inline void *dma_zalloc_coherent(struct device *dev, size_t size, dma_addr_t *dma_handle, gfp_t flag) { -- 1.7.4.4 -- 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/