linux-kernel - Re: [PATCH 02/13] dmaengine: Introduce dma_request_slave_channel_compat

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]

Date:	Thu, 25 Jun 2015 13:15:57 +0200
From:	Arnd Bergmann <arnd@...db.de>
To:	Vinod Koul <vinod.koul@...el.com>
Cc:	Peter Ujfalusi <peter.ujfalusi@...com>,
	Geert Uytterhoeven <geert@...ux-m68k.org>,
	Tony Lindgren <tony@...mide.com>,
	"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Dan Williams <dan.j.williams@...el.com>,
	dmaengine@...r.kernel.org,
	"linux-serial@...r.kernel.org" <linux-serial@...r.kernel.org>,
	"linux-omap@...r.kernel.org" <linux-omap@...r.kernel.org>,
	Linux MMC List <linux-mmc@...r.kernel.org>,
	linux-crypto@...r.kernel.org,
	linux-spi <linux-spi@...r.kernel.org>,
	Linux Media Mailing List <linux-media@...r.kernel.org>,
	ALSA Development Mailing List <alsa-devel@...a-project.org>
Subject: Re: [PATCH 02/13] dmaengine: Introduce dma_request_slave_channel_compat_reason()

On Wednesday 24 June 2015 21:54:01 Vinod Koul wrote:
> > It would be nice to find another name for the
> > dma_request_slave_channel_compat() so with the new name we could have chance
> > to rearrange the parameters: (dev, name, mask, fn, fn_param)
> > 
> > We would end up with the following APIs, all returning with error code on failure:
> > dma_request_slave_channel(dev, name);
> > dma_request_channel_legacy(mask, fn, fn_param);
> > dma_request_slave_channel_compat(mask, fn, fn_param, dev, name);
> > dma_request_any_channel(mask);
> This is good idea but still we end up with 4 APIs. Why not just converge to
> two API, one legacy + memcpy + filer fn and one untimate API for slave?
> 
> Internally we may have 4 APIs for cleaner handling...
> 

Not sure if it's realistic, but I think it would be nice to have
a way for converting the current slave drivers that use the
mask/filter/param API to the dev/name based API. We should
be able to do this by registering a lookup table from platform
code that translates one to the other, like we do with the
clkdev lookup to find a device clock based on a local identifier.

The main downside of this is that it's a lot of work if we want
to completely remove dma_request_channel() for slave drivers,
but it could be done more gradually.

Another upside is that we could come up with a mechanism to
avoid the link-time dependency on the filter-function that
causes problems when that filter is defined in a loadable
module for the dmaengine driver.

	Arnd
--
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/