linux-kernel - Re: [PATCH] dmaengine: at_hdmac: add DMA slave transfers

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Fri, 24 Jul 2009 22:29:19 +0900 (JST)
From:	Atsushi Nemoto <anemo@....ocn.ne.jp>
To:	nicolas.ferre@...el.com
Cc:	dan.j.williams@...el.com, maciej.sosnowski@...el.com,
	linux-arm-kernel@...ts.arm.linux.org.uk, patrice.vilchez@...el.com,
	linux-kernel@...r.kernel.org, haavard.skinnemoen@...el.com
Subject: Re: [PATCH] dmaengine: at_hdmac: add DMA slave transfers

On Fri, 24 Jul 2009 09:35:37 +0200, Nicolas Ferre <nicolas.ferre@...el.com> wrote:
> > Seems straightforward and self contained, applied.  Just curious which
> > drivers will take advantage of this slave capability?  As it stands I
> > do not see any in-tree users of at_hdmac beyond dmatest?
> 
> Well, in fact the same as dw_dmac: atmel-mci. Adaptation of other
> drivers are coming: probably ac97 and spi interfaces.
> 
> The patches for adaptation of atmel-mci to at_hdmac are coming...

Your atc_chain_complete() calls dma_unmap_xxx unless
DMA_COMPL_SKIP_XXX_UNMAP specified.  But atmel-mci driver does not set
the flag on dma_async_tx_descriptor.  I suppose one of them should be
fixed.

It is not clear for me how dma driver should handle unmapping on
completion of slave DMA.  Are there any consensus on it?

I enclosed unmapping code of txx9dmac driver by "if (!slave)" and did
not use DMA_COMPL_SKIP_XXX_UNMAP flag in its client driver (txx9aclc
ASoC driver).  If consensus made on how to handle unmapping on slave
DMA, I will follow it.

---
Atsushi Nemoto
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/