Hi Tomasz,
On Friday 20 January 2012 16:53:20 Tomasz Stanislawski wrote:
> On 01/20/2012 04:12 PM, Laurent Pinchart wrote:
> > 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<pawel@xxxxxxxxxx> 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.
I haven't looked into the details, but that sounds good to me. Do we have use
cases where a queue is allocated before knowing which physical device it will
be used for ?
--
Regards,
Laurent Pinchart
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