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

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

Date:	Mon, 22 Jun 2015 14:31:00 +0300
From:	Peter Ujfalusi <peter.ujfalusi@...com>
To:	Vinod Koul <vinod.koul@...el.com>
CC:	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 06/12/2015 03:58 PM, Vinod Koul wrote:
> Sorry this slipped thru

I was away for a week anyways ;)

> Thinking about it again, I think we should coverge to two APIs and mark the
> legacy depracuated and look to convert folks and phase that out

Currently, w/o this series we have these APIs:
/* to be used with DT/ACPI */
dma_request_slave_channel(dev, name)		/* NULL on failure */
dma_request_slave_channel_reason(dev, name)	/* error code on failure */

/* Legacy mode only - no DT/ACPI lookup */
dma_request_channel(mask, fn, fn_param) /* NULL on failure */

/* to be used with DT/ACPI or legacy boot */
dma_request_slave_channel_compat(mask, fn, fn_param, dev, name)	/* NULL on
failure */

To request _any_ channel to be used for memcpy one has to use
dma_request_channel(mask, NULL, NULL);

If I did not missed something.

As we need different types of parameters for DT/ACPI and legacy (non DT/ACPI
lookup) and the good API names are already taken, we might need to settle:

/* to be used with DT/ACPI */
dma_request_slave_channel(dev, name) /* error code on failure */
- Convert users to check IS_ERR_OR_NULL() instead against NULL
- Mark dma_request_slave_channel_reason() deprecated and convert the current users

/* to be used with DT/ACPI or legacy boot */
dma_request_slave_channel_compat(mask, fn, fn_param, dev, name) /* error code
on failure */
- Convert users to check IS_ERR_OR_NULL() instead against NULL
- Do not try legacy mode if either OF or ACPI failed because of real error

/* Legacy mode only - no DT/ACPI lookup */
dma_request_channel_legacy(mask, fn, fn_param) /* error code on failure */
- convert users of dma_request_channel()
- mark dma_request_channel() deprecated

/* to be used to get a channel for memcpy for example */
dma_request_any_channel(mask) /* error code on failure */
- Convert current dma_request_channel(mask, NULL, NULL) users
I know, any of the other function could be prepared to handle this when
parameters are missing, but it is a bit cleaner to have separate API for this.

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);

What do you think?

-- 
Péter
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
Please read the FAQ at  http://www.tux.org/lkml/