Hello Hans, Michael and Marek, Thanks a lot for your feedback. On 07/18/2016 04:34 AM, Hans Verkuil wrote: > On 07/15/2016 06:26 PM, Javier Martinez Canillas wrote: >> The buffer planes' dma-buf are currently mapped when buffers are queued >> from userspace but it's more appropriate to do the mapping when buffers >> are queued in the driver since that's when the actual DMA operation are >> going to happen. > > Does this solve anything? Once the DMA has started the behavior is the same > as before (QBUF maps the dmabuf), only while the DMA engine hasn't started > yet are the QBUF calls just accepted and the mapping takes place when the > DMA is kickstarted. This makes QBUF behave inconsistently. > > You don't describe here WHY this change is needed. > Nicolas pointed me to the TODO and suggested me the patch for the reasons he explained in his latest email. And yes, this should had been tagged as a RFC and just to know what you think about it. Sorry for missing that. > I'm not sure I agree with the TODO, and even if I did, I'm not sure I agree > with this solution. Since queuing the buffer to the driver is not the same > as 'just before the DMA', since there may be many buffers queued up in the > driver and you don't know in vb2 when the buffer is at the 'just before the DMA' > stage. > Right, I meant "as closer as possible to when the actual DMA is going to happen" rather than "just before the DMA". > Regards, > > Hans > Best regards, -- Javier Martinez Canillas Open Source Group Samsung Research America -- 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
