Hi Laurent,

On 01/20/2012 04:12 PM, Laurent Pinchart wrote:
Hi Tomasz,

On Friday 20 January 2012 11:58:39 Tomasz Stanislawski wrote:
On 01/20/2012 11:41 AM, Sumit Semwal wrote:
On 20 January 2012 00:37, Pawel Osciak<pa...@osciak.com>   wrote:
Hi Sumit,
Thank you for your work. Please find my comments below.

Hi Pawel,

<snip>
   struct vb2_mem_ops {

         void            *(*alloc)(void *alloc_ctx, unsigned long size);

@@ -65,6 +82,16 @@ struct vb2_mem_ops {

                                         unsigned long size, int write);

         void            (*put_userptr)(void *buf_priv);

+       /* Comment from Rob Clark: XXX: I think the attach / detach
could be handled +        * in the vb2 core, and vb2_mem_ops really
just need to get/put the +        * sglist (and make sure that the
sglist fits it's needs..) +        */

I *strongly* agree with Rob here. Could you explain the reason behind
not doing this?
Allocator should ideally not have to be aware of attaching/detaching,
this is not specific to an allocator.

Ok, I thought we'll start with this version first, and then refine.
But you guys are right.

I think that it is not possible to move attach/detach to vb2-core. The
problem is that dma_buf_attach needs 'struct device' argument. This
pointer is not available in vb2-core. This pointer is delivered by
device's driver in "void *alloc_context".

Moving information about device would introduce new problems like:
- breaking layering in vb2
- some allocators like vb2-vmalloc do not posses any device related
attributes

What about passing the device to vb2-core then ?


IMO, One way to do this is adding field 'struct device *dev' to struct vb2_queue. This field should be filled by a driver prior to calling vb2_queue_init.

Regards,
Tomasz Stanislawski

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