Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751888Ab0HTUFi (ORCPT ); Fri, 20 Aug 2010 16:05:38 -0400 Received: from mailout-de.gmx.net ([213.165.64.23]:41862 "HELO mail.gmx.net" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with SMTP id S1751792Ab0HTUFg (ORCPT ); Fri, 20 Aug 2010 16:05:36 -0400 X-Authenticated: #20450766 X-Provags-ID: V01U2FsdGVkX19LXHkoEB1LBNsAM3LPcvbeLAw5LJxElz7T76JeEG rUqnGPs0R4z924 Date: Fri, 20 Aug 2010 22:05:30 +0200 (CEST) From: Guennadi Liakhovetski To: Marin Mitov cc: linux-kernel@vger.kernel.org, Linux Media Mailing List , FUJITA Tomonori , Greg KH , linux-arm-kernel@lists.infradead.org, linux-sh@vger.kernel.org, Russell King - ARM Linux Subject: Re: [RFC][PATCH] add dma_reserve_coherent_memory()/dma_free_reserved_memory() API In-Reply-To: <201008191818.36068.mitov@issp.bas.bg> Message-ID: References: <201008191818.36068.mitov@issp.bas.bg> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-Y-GMX-Trusted: 0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4825 Lines: 142 On Thu, 19 Aug 2010, Marin Mitov wrote: > Hi all, > > struct device contains a member: struct dma_coherent_mem *dma_mem; > to hold information for a piece of memory declared dma-coherent. > Alternatively the same member could also be used to hold preallocated > dma-coherent memory for latter per-device use. > > This tric is already used in drivers/staging/dt3155v4l.c > dt3155_alloc_coherent()/dt3155_free_coherent() > > Here proposed for general use by popular demand from video4linux folks. > Helps for videobuf-dma-contig framework. Ok, so, we've got two solutions to this problem submitted on the same day;) Following this thread: http://marc.info/?t=128128236400002&r=1&w=2 on the ARM Linux kernel ML, I submitted a patch series http://thread.gmane.org/gmane.linux.ports.sh.devel/8595 with a couple of fixes and improvements, the actual new API and a use example. My approach is slightly different, in that instead of requiring drivers to issue two calls - one to reserve RAM (usually dma_alloc_coherent()) and one to assign it to a device, my patch follows the suggestion from Russell King from the first thread and unites these two operations. So, now we have a choice;) Unfortunately, these two patch series went to orthogonal sets of recepients, I'm trying to fix this by adding a couple of CC entries. Thanks Guennadi > > Signed-off-by: Marin Mitov > > ====================================================================== > --- a/drivers/base/dma-coherent.c 2010-08-19 15:50:42.000000000 +0300 > +++ b/drivers/base/dma-coherent.c 2010-08-19 17:27:56.000000000 +0300 > @@ -93,6 +93,83 @@ void *dma_mark_declared_memory_occupied( > EXPORT_SYMBOL(dma_mark_declared_memory_occupied); > > /** > + * dma_reserve_coherent_memory() - reserve coherent memory for per-device use > + * > + * @dev: device from which we allocate memory > + * @size: size of requested memory area in bytes > + * @flags: same as in dma_declare_coherent_memory() > + * > + * This function reserves coherent memory allocating it early (during probe()) > + * to support latter allocations from per-device coherent memory pools. > + * For a given device one could use either dma_declare_coherent_memory() or > + * dma_reserve_coherent_memory(), but not both, becase the result of these > + * functions is stored in a single struct device member - dma_mem > + * > + * Returns DMA_MEMORY_MAP on success, or 0 if failed. > + * (same as dma_declare_coherent_memory() > + */ > +int dma_reserve_coherent_memory(struct device *dev, size_t size, int flags) > +{ > + struct dma_coherent_mem *mem; > + dma_addr_t dev_base; > + int pages = size >> PAGE_SHIFT; > + int bitmap_size = BITS_TO_LONGS(pages) * sizeof(long); > + > + if ((flags & DMA_MEMORY_MAP) == 0) > + goto out; > + if (!size) > + goto out; > + if (dev->dma_mem) > + goto out; > + > + mem = kzalloc(sizeof(*mem), GFP_KERNEL); > + if (!mem) > + goto out; > + mem->virt_base = dma_alloc_coherent(dev, size, &dev_base, > + DT3155_COH_FLAGS); > + if (!mem->virt_base) > + goto err_alloc_coherent; > + mem->bitmap = kzalloc(bitmap_size, GFP_KERNEL); > + if (!mem->bitmap) > + goto err_bitmap; > + > + mem->device_base = dev_base; > + mem->size = pages; > + mem->flags = flags; > + dev->dma_mem = mem; > + return DMA_MEMORY_MAP; > + > +err_bitmap: > + dma_free_coherent(dev, size, mem->virt_base, dev_base); > +err_alloc_coherent: > + kfree(mem); > +out: > + return 0; > +} > +EXPORT_SYMBOL(dma_reserve_coherent_memory); > + > +/** > + * dma_free_reserved_memory() - free the reserved dma-coherent memoty > + * > + * @dev: device for which we free the dma-coherent memory > + * > + * same as dma_release_declared_memory() > + */ > +void dma_free_reserved_memory(struct device *dev) > +{ > + struct dma_coherent_mem *mem = dev->dma_mem; > + > + if (!mem) > + return; > + dev->dma_mem = NULL; > + dma_free_coherent(dev, mem->size << PAGE_SHIFT, > + mem->virt_base, mem->device_base); > + kfree(mem->bitmap); > + kfree(mem); > +} > +EXPORT_SYMBOL(dma_free_reserved_memory); > + > +/** > * dma_alloc_from_coherent() - try to allocate memory from the per-device coherent area > * > * @dev: device from which we allocate memory > -- > 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/ > --- Guennadi Liakhovetski, Ph.D. Freelance Open-Source Software Developer http://www.open-technology.de/ -- 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/