From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751727AbaIJHBm (ORCPT ); Wed, 10 Sep 2014 03:01:42 -0400 Received: from smtp-vbr1.xs4all.nl ([194.109.24.21]:2335 "EHLO smtp-vbr1.xs4all.nl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751038AbaIJHBl (ORCPT ); Wed, 10 Sep 2014 03:01:41 -0400 Message-ID: <540FF70E.9050203@xs4all.nl> Date: Wed, 10 Sep 2014 09:00:30 +0200 From: Hans Verkuil User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Icedove/24.5.0 MIME-Version: 1.0 To: Fancy Fang , m.chehab@samsung.com, viro@ZenIV.linux.org.uk CC: shawn.guo@freescale.com, linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, Marek Szyprowski Subject: Re: [PATCH] [media] videobuf-dma-contig: replace vm_iomap_memory() with remap_pfn_range(). References: <1410326937-31140-1-git-send-email-chen.fang@freescale.com> In-Reply-To: <1410326937-31140-1-git-send-email-chen.fang@freescale.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 09/10/14 07:28, Fancy Fang wrote: > When user requests V4L2_MEMORY_MMAP type buffers, the videobuf-core > will assign the corresponding offset to the 'boff' field of the > videobuf_buffer for each requested buffer sequentially. Later, user > may call mmap() to map one or all of the buffers with the 'offset' > parameter which is equal to its 'boff' value. Obviously, the 'offset' > value is only used to find the matched buffer instead of to be the > real offset from the buffer's physical start address as used by > vm_iomap_memory(). So, in some case that if the offset is not zero, > vm_iomap_memory() will fail. Is this just a fix for something that can fail theoretically, or do you actually have a case where this happens? I am very reluctant to make any changes to videobuf. Drivers should all migrate to vb2. I have CC-ed Marek as well since he knows a lot more about this stuff than I do. Regards, Hans > > Signed-off-by: Fancy Fang > --- > drivers/media/v4l2-core/videobuf-dma-contig.c | 4 +++- > 1 file changed, 3 insertions(+), 1 deletion(-) > > diff --git a/drivers/media/v4l2-core/videobuf-dma-contig.c b/drivers/media/v4l2-core/videobuf-dma-contig.c > index bf80f0f..8bd9889 100644 > --- a/drivers/media/v4l2-core/videobuf-dma-contig.c > +++ b/drivers/media/v4l2-core/videobuf-dma-contig.c > @@ -305,7 +305,9 @@ static int __videobuf_mmap_mapper(struct videobuf_queue *q, > /* Try to remap memory */ > size = vma->vm_end - vma->vm_start; > vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot); > - retval = vm_iomap_memory(vma, mem->dma_handle, size); > + retval = remap_pfn_range(vma, vma->vm_start, > + mem->dma_handle >> PAGE_SHIFT, > + size, vma->vm_page_prot); > if (retval) { > dev_err(q->dev, "mmap: remap failed with error %d. ", > retval); >