From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756860Ab0GNRHS (ORCPT ); Wed, 14 Jul 2010 13:07:18 -0400 Received: from mta-mad.optenet.com ([130.117.93.253]:61215 "EHLO mta-mad.optenet.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751721Ab0GNRHQ (ORCPT ); Wed, 14 Jul 2010 13:07:16 -0400 Date: Wed, 14 Jul 2010 19:07:14 +0200 (CEST) From: Unai Uribarri To: Marin Mitov Cc: linux-kernel Message-ID: <12797200.68401279127234158.JavaMail.root@mail1-md.optenet.com> In-Reply-To: <28112199.68371279127209288.JavaMail.root@mail1-md.optenet.com> Subject: Re: Workaround hardware bug addressing physical address MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-Originating-IP: [192.168.3.29] X-Mailer: Zimbra 5.0.11_GA_2695.UBUNTU8 (ZimbraWebClient - FF3.0 (Linux)/5.0.11_GA_2695.UBUNTU8) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org ----- "Marin Mitov" wrote: | Hi, | | This is pci driver. You can set dma mask: | | dma_set_coheren_mask(pdev, DMA_BIT_MASK(31)) | | All further alloc_coherent() should be from the region 0-2GB. | But I'm using a 64 bit operating system with 32GB of RAM. It's a pity to be unable to use 4GB-32GB range because the 2-4GB range is unusable. So I've written this code to skip invalid areas. Do you think this code could be useful for other drivers? /** Structure used to store all the information about a DMA allocation which is * needed to free it. It also has a next field to chain the allocations. */ typedef struct dma_allocation { struct device *dev; size_t size; dma_addr_t dma_handle; struct list_head list; } dma_allocation_t; /** Validates a dma allocation * @param{in} ptr is the pointer to the allocated dma memory * @param{in} dma_handle is the handle to the allocated dma memory * @return 0 if the allocation isn't valid. */ typedef int (*dma_validator_t)(void *ptr, struct device *dev, size_t size, dma_addr_t handle); /** Allocates validated coherent DMA memory. * * Same paremeters and return value as dma_alloc_coherent, and: * @param{in} invalid_allocs is a pointer to a list where invalid allocations are enqueued * @param{in} validator is the validation function * * While the chunk of memory allocated by dma_alloc_coherent doesn't pass the validator filter, * it's queued in invalid_allocs and another chunk of memory is allocated. */ static void *dma_validated_alloc_coherent(struct list_head *invalid_allocs, dma_validator_t validator, struct device *dev, size_t size, dma_addr_t *dma_handle, gfp_t flag) { void *res = dma_alloc_coherent(dev, size, dma_handle, flag); while (!IS_ERR(res) && !validator(res, dev, size, *dma_handle)) { dma_allocation_t *entry = res; entry->dev = dev; entry->size = size; entry->dma_handle = *dma_handle; list_add_tail(&entry->list, invalid_allocs); res = dma_alloc_coherent(dev, size, dma_handle, flag); } return res; } /** Frees all the coherent dma allocations contained in list */ static void dma_list_free_coherent(struct list_head *list) { dma_allocation_t *cur, *next; list_for_each_entry_safe(cur, next, list, list) { dma_free_coherent(cur->dev, cur->size, cur, cur->dma_handle); } }