On 09/10/14 09:14, chen.fang@xxxxxxxxxxxxx wrote: > It is not a theoretically issue, it is a real case that the mapping failed issue happens in 3.14.y kernel but not happens in previous 3.10.y kernel. > So I need your confirmation on it. With which driver does this happen? On which architecture? Regards, Hans > > Thanks. > > Best regards, > Fancy Fang > > -----Original Message----- > From: Hans Verkuil [mailto:hverkuil@xxxxxxxxx] > Sent: Wednesday, September 10, 2014 3:01 PM > To: Fang Chen-B47543; m.chehab@xxxxxxxxxxx; viro@xxxxxxxxxxxxxxxxxx > Cc: Guo Shawn-R65073; linux-media@xxxxxxxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; Marek Szyprowski > Subject: Re: [PATCH] [media] videobuf-dma-contig: replace vm_iomap_memory() with remap_pfn_range(). > > 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 <chen.fang@xxxxxxxxxxxxx> >> --- >> 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); >> > -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
