linux-kernel - Re: [RFC 2/4] dma: add dmaengine driver for Samsung s3c24xx SoCs

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 for Android: free password hash cracker in your pocket

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

Message-ID: <CACRpkdY1s7u9Xjzkb+AdFY1xEO1PQOp1ZFPf4r5qPL-=WPkvNQ@mail.gmail.com>
Date:	Wed, 15 May 2013 20:38:05 +0200
From:	Linus Walleij <linus.walleij@...aro.org>
To:	Heiko Stübner <heiko@...ech.de>
Cc:	Russell King - ARM Linux <linux@....linux.org.uk>,
	Dan Williams <djbw@...com>, Vinod Koul <vinod.koul@...el.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	linux-samsung-soc <linux-samsung-soc@...r.kernel.org>,
	Kukjin Kim <kgene.kim@...sung.com>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>
Subject: Re: [RFC 2/4] dma: add dmaengine driver for Samsung s3c24xx SoCs

On Tue, May 14, 2013 at 3:51 PM, Heiko Stübner <heiko@...ech.de> wrote:
> Am Dienstag, 14. Mai 2013, 14:47:19 schrieb Linus Walleij:
>> On Sat, May 11, 2013 at 1:31 PM, Heiko Stübner <heiko@...ech.de> wrote:
>> > Conceptually the s3c24xx-dma feels like a distant relative of the pl08x
>> > with numerous virtual channels being mapped to a lot less physical ones.
>> > The driver therefore borrows a lot from the amba-pl08x driver in this
>> > regard. Functionality-wise the driver gains a memcpy ability in addition
>> > to the slave_sg one.
>> >
>> > The driver currently only supports the "newer" SoCs which can use any
>> > physical channel for any dma slave. Support for the older SoCs where
>> > each channel only supports a subset of possible dma slaves will have to
>> > be added later.
>> >
>> > Tested on a s3c2416-based board, memcpy using the dmatest module and
>> > slave_sg partially using the spi-s3c64xx driver.
>> >
>> > Signed-off-by: Heiko Stuebner <heiko@...ech.de>
>>
>> So have I understood correctly if I assume that *some* S3C
>> variants, i.e. this: arch/arm/mach-s3c64xx/dma.c
>> have a vanilla, unmodified, or just slightly modified
>> PL08x block, while this DMAC is something probably based on
>> the PL08x where some ASIC engineer has had a good time hacking
>> around in the VHDL code to meet some feature requirements.
>> Correct? Or plausible guess?
>
> You're guess is at good as mine :-) . The public s3c64xx (ARM11 based)
> documentation says that it is using s PL080 as dma controller while the
> s3c24xx (ARM9 based) SoCs have this one, which doesn't come with any label in
> the manuals.
> Similar to the s3c64xx using a vic, while the s3c24xx uses something
> homegrown.
>
> The relationship description was more based on the concepts used, i.e. the
> virtual channel concept and general handling of dma transfers feel somehow
> similar - as I said these are my first steps into this, so I still need to
> understand a lot.

OK then, a separate driver seems required, will look a bit closer at
the patch as such.

Yours,
Linus Walleij
--
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/