Hi Laurent,
Thanks for review.
On 04/06/2012 05:12 PM, Laurent Pinchart wrote:
> Hi Tomasz,
>
> On Thursday 05 April 2012 16:00:08 Tomasz Stanislawski wrote:
>> From: Sumit Semwal <sumit.semwal@xxxxxx>
>>
>> This patch makes changes for adding dma-contig as a dma_buf user. It
>> provides function implementations for the {attach, detach, map,
>> unmap}_dmabuf() mem_ops of DMABUF memory type.
>>
>> Signed-off-by: Sumit Semwal <sumit.semwal@xxxxxx>
>> Signed-off-by: Sumit Semwal <sumit.semwal@xxxxxxxxxx>
>> [author of the original patch]
>> Signed-off-by: Tomasz Stanislawski <t.stanislaws@xxxxxxxxxxx>
>> [integration with refactored dma-contig allocator]
>> ---
>> drivers/media/video/videobuf2-dma-contig.c | 117 +++++++++++++++++++++++++
>> 1 files changed, 117 insertions(+), 0 deletions(-)
>>
>> diff --git a/drivers/media/video/videobuf2-dma-contig.c
>> b/drivers/media/video/videobuf2-dma-contig.c index 30f316588..6329483
>> 100644
>> --- a/drivers/media/video/videobuf2-dma-contig.c
>> +++ b/drivers/media/video/videobuf2-dma-contig.c
>> @@ -10,6 +10,7 @@
>> * the Free Software Foundation.
>> */
>>
>> +#include <linux/dma-buf.h>
>> #include <linux/module.h>
>> #include <linux/scatterlist.h>
>> #include <linux/sched.h>
>> @@ -33,6 +34,9 @@ struct vb2_dc_buf {
>>
>> /* USERPTR related */
>> struct vm_area_struct *vma;
>> +
>> + /* DMABUF related */
>> + struct dma_buf_attachment *db_attach;
>> };
>>
>> /*********************************************/
>> @@ -425,6 +429,115 @@ fail_buf:
>> }
>>
>> /*********************************************/
>> +/* callbacks for DMABUF buffers */
>> +/*********************************************/
>> +
>> +static int vb2_dc_map_dmabuf(void *mem_priv)
>> +{
>> + struct vb2_dc_buf *buf = mem_priv;
>> + struct sg_table *sgt;
>> + unsigned long contig_size;
>> + int ret = 0;
>> +
>> + if (WARN_ON(!buf->db_attach)) {
>> + printk(KERN_ERR "trying to pin a non attached buffer\n");
>> + return -EINVAL;
>> + }
>> +
>> + if (WARN_ON(buf->dma_sgt)) {
>> + printk(KERN_ERR "dmabuf buffer is already pinned\n");
>> + return 0;
>> + }
>> +
>> + /* get the associated scatterlist for this buffer */
>> + sgt = dma_buf_map_attachment(buf->db_attach, buf->dma_dir);
>> + if (IS_ERR_OR_NULL(sgt)) {
>> + printk(KERN_ERR "Error getting dmabuf scatterlist\n");
>> + return -EINVAL;
>> + }
>> +
>> + /* checking if dmabuf is big enough to store contiguous chunk */
>> + contig_size = vb2_dc_get_contiguous_size(sgt);
>> + if (contig_size < buf->size) {
>> + printk(KERN_ERR "contiguous chunk of dmabuf is too small\n");
>> + ret = -EFAULT;
>> + goto fail_map;
>
> The fail_map label is only used here, you can move the
> dma_buf_unmap_attachment() call here and return -EFAULT directly.
>
Patch "[RFC 07/13] v4l: vb2-dma-contig: change map/unmap behaviour for importers"
introduces other cleanup labels. Anyway I will remove this redundant label as
you proposed.
>> + }
>> +
>> + buf->dma_addr = sg_dma_address(sgt->sgl);
>> + buf->dma_sgt = sgt;
>> +
>> + return 0;
>> +
>> +fail_map:
>> + dma_buf_unmap_attachment(buf->db_attach, sgt, buf->dma_dir);
>> +
>> + return ret;
>> +}
>> +
>> +static void vb2_dc_unmap_dmabuf(void *mem_priv)
>> +{
>> + struct vb2_dc_buf *buf = mem_priv;
>> + struct sg_table *sgt = buf->dma_sgt;
>> +
>> + if (WARN_ON(!buf->db_attach)) {
>> + printk(KERN_ERR "trying to unpin a not attached buffer\n");
>> + return;
>> + }
>> +
>> + if (WARN_ON(!sgt)) {
>> + printk(KERN_ERR "dmabuf buffer is already unpinned\n");
>> + return;
>> + }
>> +
>> + dma_buf_unmap_attachment(buf->db_attach, sgt, buf->dma_dir);
>> +
>> + buf->dma_addr = 0;
>> + buf->dma_sgt = NULL;
>> +}
>> +
>> +static void vb2_dc_detach_dmabuf(void *mem_priv)
>> +{
>> + struct vb2_dc_buf *buf = mem_priv;
>> +
>> + if (buf->dma_addr)
>> + vb2_dc_unmap_dmabuf(buf);
>
> What would you think about calling vb2_dc_unmap_dmabuf() from vb2 core
> instead, to keep the map/unmap calls symmetrical (the second WARN_ON and the
> related printk in vb2_dc_unmap_dmabuf() might need to go then) ?
>
Detach without unmap may happen in a case of closing a video fd
without prior dequeuing of all buffers.
A call map_dmabuf should be moved to __enqueue_in_driver and add calling
unmap_dmabuf to vb2_buffer_done in order to keep map/unmap calls
symmetrical. I'll check if this could work.
Regards,
Tomasz Stanislawski
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