From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ralf Baechle Subject: Re: [PATCH] MIPS: Fixups of ALSA memory maps Date: Mon, 16 Nov 2009 18:43:24 +0100 Message-ID: <20091116174324.GA17748@linux-mips.org> References: <9cbcd06037c18288a6493459b8f3a6e1562eca77.1258389992.git.wuzhangjin@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: Received: from eddie.linux-mips.org (eddie.linux-mips.org [78.24.191.182]) by alsa0.perex.cz (Postfix) with ESMTP id 20A9A103916 for ; Mon, 16 Nov 2009 18:43:22 +0100 (CET) Received: from localhost.localdomain ([127.0.0.1]:44699 "EHLO h5.dl5rb.org.uk" rhost-flags-OK-OK-OK-FAIL) by ftp.linux-mips.org with ESMTP id S1493794AbZKPRnV (ORCPT ); Mon, 16 Nov 2009 18:43:21 +0100 Content-Disposition: inline In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: alsa-devel-bounces@alsa-project.org Errors-To: alsa-devel-bounces@alsa-project.org To: Takashi Iwai , Thomas Bogendoerfer Cc: linux-mips@linux-mips.org, alsa-devel@alsa-project.org, Wu Zhangjin , linux-kernel@vger.kernel.org, Wu Zhangjin List-Id: alsa-devel@alsa-project.org On Mon, Nov 16, 2009 at 06:12:22PM +0100, Takashi Iwai wrote: > Actually, this has been a looong-standing problem. > I have a series of patches to fix these issues, but it's more > intensively involved with dma_*() functions. > > The patches can be found in test/dma-fix branch of sound GIT tree. > git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound-2.6.git test/dma-fix > > This basically adds dma_mmap_coherent() function to feasible > architectures, which is already implemented for ARM, so far. Cool - but needs a little further tweaking to work right. That's a solution which will use uncached accesses on all MIPS systems. IP27/IP35-family machines will explode when you try that. Eventually the cache coherency logic will notice that cache, directory caches and memory have become inconsistent and bombard the CPU with a bunch of nasty exceptions. For cache-coherent machines otoh it's a big waste of performance. int dma_mmap_coherent(struct device *dev, struct vm_area_struct *vma, void *cpu_addr, dma_addr_t handle, size_t size) { struct page *pg; if (!plat_device_is_coherent(dev)) vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot); cpu_addr = (void *)dma_addr_to_virt(handle); pg = virt_to_page(cpu_addr); return remap_pfn_range(vma, vma->vm_start, page_to_pfn(pg) + vma->vm_pgoff, size, vma->vm_page_prot); } EXPORT_SYMBOL(dma_mmap_coherent); Thomas - you're the IP28 specialist. Would the plat_device_is_coherent() above have to become a cpu_is_noncoherent_r10000() call? Any further nasties? Ralf From mboxrd@z Thu Jan 1 00:00:00 1970 Received: with ECARTIS (v1.0.0; list linux-mips); Mon, 16 Nov 2009 18:43:30 +0100 (CET) Received: from localhost.localdomain ([127.0.0.1]:44707 "EHLO h5.dl5rb.org.uk" rhost-flags-OK-OK-OK-FAIL) by ftp.linux-mips.org with ESMTP id S1493794AbZKPRn1 (ORCPT ); Mon, 16 Nov 2009 18:43:27 +0100 Received: from h5.dl5rb.org.uk (localhost.localdomain [127.0.0.1]) by h5.dl5rb.org.uk (8.14.3/8.14.3) with ESMTP id nAGHhR84017964; Mon, 16 Nov 2009 18:43:28 +0100 Received: (from ralf@localhost) by h5.dl5rb.org.uk (8.14.3/8.14.3/Submit) id nAGHhOO9017962; Mon, 16 Nov 2009 18:43:24 +0100 Date: Mon, 16 Nov 2009 18:43:24 +0100 From: Ralf Baechle To: Takashi Iwai , Thomas Bogendoerfer Cc: Wu Zhangjin , Jaroslav Kysela , alsa-devel@alsa-project.org, linux-mips@linux-mips.org, linux-kernel@vger.kernel.org, Wu Zhangjin Subject: Re: [PATCH] MIPS: Fixups of ALSA memory maps Message-ID: <20091116174324.GA17748@linux-mips.org> References: <9cbcd06037c18288a6493459b8f3a6e1562eca77.1258389992.git.wuzhangjin@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.19 (2009-01-05) Return-Path: X-Envelope-To: <"|/home/ecartis/ecartis -s linux-mips"> (uid 0) X-Orcpt: rfc822;linux-mips@linux-mips.org Original-Recipient: rfc822;linux-mips@linux-mips.org X-archive-position: 24934 X-ecartis-version: Ecartis v1.0.0 Sender: linux-mips-bounce@linux-mips.org Errors-to: linux-mips-bounce@linux-mips.org X-original-sender: ralf@linux-mips.org Precedence: bulk X-list: linux-mips On Mon, Nov 16, 2009 at 06:12:22PM +0100, Takashi Iwai wrote: > Actually, this has been a looong-standing problem. > I have a series of patches to fix these issues, but it's more > intensively involved with dma_*() functions. > > The patches can be found in test/dma-fix branch of sound GIT tree. > git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound-2.6.git test/dma-fix > > This basically adds dma_mmap_coherent() function to feasible > architectures, which is already implemented for ARM, so far. Cool - but needs a little further tweaking to work right. That's a solution which will use uncached accesses on all MIPS systems. IP27/IP35-family machines will explode when you try that. Eventually the cache coherency logic will notice that cache, directory caches and memory have become inconsistent and bombard the CPU with a bunch of nasty exceptions. For cache-coherent machines otoh it's a big waste of performance. int dma_mmap_coherent(struct device *dev, struct vm_area_struct *vma, void *cpu_addr, dma_addr_t handle, size_t size) { struct page *pg; if (!plat_device_is_coherent(dev)) vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot); cpu_addr = (void *)dma_addr_to_virt(handle); pg = virt_to_page(cpu_addr); return remap_pfn_range(vma, vma->vm_start, page_to_pfn(pg) + vma->vm_pgoff, size, vma->vm_page_prot); } EXPORT_SYMBOL(dma_mmap_coherent); Thomas - you're the IP28 specialist. Would the plat_device_is_coherent() above have to become a cpu_is_noncoherent_r10000() call? Any further nasties? Ralf