linux-kernel - Re: Tearing down DMA transfer setup after DMA client has finished

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]

Message-ID: <20161208103730.GB6408@localhost>
Date:   Thu, 8 Dec 2016 16:07:30 +0530
From:   Vinod Koul <vinod.koul@...el.com>
To:     Måns Rullgård <mans@...sr.com>
Cc:     Mason <slash.tmp@...e.fr>, Russell King <linux@....linux.org.uk>,
        dmaengine@...r.kernel.org,
        Linus Walleij <linus.walleij@...aro.org>,
        Dan Williams <dan.j.williams@...el.com>,
        LKML <linux-kernel@...r.kernel.org>,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        Jon Mason <jdmason@...zu.us>, Mark Brown <broonie@...nel.org>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Lee Jones <lee.jones@...aro.org>,
        Laurent Pinchart <laurent.pinchart@...asonboard.com>,
        Arnd Bergmann <arnd@...db.de>,
        Maxime Ripard <maxime.ripard@...e-electrons.com>,
        Dave Jiang <dave.jiang@...el.com>,
        Peter Ujfalusi <peter.ujfalusi@...com>,
        Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
        Sebastian Frias <sf84@...oste.net>,
        Thibaud Cornic <thibaud_cornic@...madesigns.com>
Subject: Re: Tearing down DMA transfer setup after DMA client has finished

On Wed, Dec 07, 2016 at 04:44:55PM +0000, Måns Rullgård wrote:
> Vinod Koul <vinod.koul@...el.com> writes:
> >> 
> >> What you're proposing, Vinod, is to make a channel exclusive
> >> to a driver, as long as the driver has not explicitly released
> >> the channel, via dma_release_channel(), right?
> >
> > Precisely, but yes the downside of that is concurrent access are
> > limited, but am not sure if driver implements virtual channels and
> > allows that..
> 
> My driver implements virtual channels.  The problem is that the physical
> dma channels signal completion slightly too soon, at least with
> mem-to-device transfers.  Apparently we need to keep the sbox routing
> until the peripheral indicates that it has actually received all the
> data.

So do we need concurrent accesses by all clients.

-- 
~Vinod