linux-kernel - Re: [PATCH 2/2] DMAENGINE: generic channel status

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] [day] [month] [year] [list]

Date:	Thu, 25 Mar 2010 17:05:20 -0700
From:	Dan Williams <dan.j.williams@...el.com>
To:	Guennadi Liakhovetski <g.liakhovetski@....de>
Cc:	Linus Walleij <linus.walleij@...ricsson.com>,
	linux-kernel@...r.kernel.org,
	Maciej Sosnowski <maciej.sosnowski@...el.com>,
	Nicolas Ferre <nicolas.ferre@...el.com>,
	Pavel Machek <pavel@....cz>, Li Yang <leoli@...escale.com>,
	Paul Mundt <lethal@...ux-sh.org>,
	Ralf Baechle <ralf@...ux-mips.org>,
	Haavard Skinnemoen <haavard.skinnemoen@...el.com>,
	Magnus Damm <damm@...nsource.se>,
	Liam Girdwood <lrg@...mlogic.co.uk>,
	Mark Brown <broonie@...nsource.wolfsonmicro.com>,
	Joe Perches <joe@...ches.com>,
	Roland Dreier <rdreier@...co.com>
Subject: Re: [PATCH 2/2] DMAENGINE: generic channel status

On Thu, Mar 25, 2010 at 3:37 PM, Guennadi Liakhovetski
<g.liakhovetski@....de> wrote:
> On Thu, 25 Mar 2010, Dan Williams wrote:
>
>> On Thu, Mar 25, 2010 at 1:58 PM, Guennadi Liakhovetski
>> <g.liakhovetski@....de> wrote:
>> > On Thu, 25 Mar 2010, Linus Walleij wrote:
>> >
>> >> Convert the device_is_tx_complete() operation on the
>> >> DMA engine to a generic device_tx_status()operation which
>> >> can return three states, DMA_TX_RUNNING, DMA_TX_COMPLETE,
>> >> DMA_TX_PAUSED.
>> >>
>> [..]
>> > General: you converted all drivers to the new .device_tx_status() API, but
>> > since they don't implement "residue," you left it uninitialised
>> > everywhere. Wouldn't it be better to set it to 0 or total length,
>> > depending on the complete / not complete status?
>>
>> Agree that it should not be uninitialized.  At the same time I do not
>> want to require drivers that don't need it to go through the hassle of
>> looking up a byte count, so perhaps all but the drivers that want this
>> support can return a 'max byte count'??
>
> Why not assign one of the two - 0 if the transfer is complete (DMA_SUCCESS
> status returned) or whatever max count otherwise? Except I do think this
> might confuse some users - seeing a residue larger than the total transfer
> length...
>

0 if complete makes sense and then the actual residue or all 0xf's to
indicate "I don't support inflight residue reporting".

--
Dan
--
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/