Re: [PATCH] dmaengine: free descriptor when free chan resource

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Mon, Jul 13, 2015 at 01:00:54PM +0200, Lars-Peter Clausen wrote:
> >>>Actually there has never been a recommendation for slave cases. It came from async
> >>>API and slave users should never have used it, untill now.
> >>
> >>That doesn't reflect reality. The fast majority slave API users set
> >>the flag and some DMAengine drivers expect it to be set.
> >That is simply wrong and we need to fix that
> 
> Could you explain why you think that it is wrong?
> 
> I think we might have different understandings of what exactly the
> DMA_CTRL_ACK flag means.
This is documented now

  * DMA_CTRL_ACK
    - If set, the transfer can be reused after being completed.
    - There is a guarantee the transfer won't be freed until it is acked
      by async_tx_ack().
    - As a consequence, if a device driver wants to skip the dma_map_sg()
      and
      dma_unmap_sg() in between 2 transfers, because the DMA'd data wasn't used,
      it can resubmit the transfer right after its completion.

Any user who doesnt want this interpretation should be fixed, any driver not
doing this should be fixed :)

-- 
~Vinod

--
To unsubscribe from this list: send the line "unsubscribe dmaengine" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html



[Index of Archives]     [Linux Kernel]     [Linux ARM (vger)]     [Linux ARM MSM]     [Linux Omap]     [Linux Arm]     [Linux Tegra]     [Fedora ARM]     [Linux for Samsung SOC]     [eCos]     [Linux PCI]     [Linux Fastboot]     [Gcc Help]     [Git]     [DCCP]     [IETF Announce]     [Security]     [Linux MIPS]     [Yosemite Campsites]

  Powered by Linux