From: Russell King - ARM Linux <linux@arm.linux.org.uk>
To: Huang Shijie <b32955@freescale.com>
Cc: Vinod Koul <vinod.koul@linux.intel.com>,
djbw@fb.com, khali@linux-fr.org, ben-linux@fluff.org,
w.sang@pengutronix.de, cjb@laptop.org, dwmw2@infradead.org,
lrg@ti.com, broonie@opensource.wolfsonmicro.com, perex@perex.cz,
tiwai@suse.de, shawn.guo@linaro.org, marex@denx.de,
artem.bityutskiy@linux.intel.com, linux-kernel@vger.kernel.org,
linux-i2c@vger.kernel.org, linux-mmc@vger.kernel.org,
linux-mtd@lists.infradead.org, alsa-devel@alsa-project.org,
linux-arm-kernel@lists.infradead.org,
Huang Shijie <shijie8@gmail.com>
Subject: Re: [PATCH] dma: add new DMA control commands
Date: Thu, 18 Oct 2012 09:52:08 +0100 [thread overview]
Message-ID: <20121018085208.GR21164@n2100.arm.linux.org.uk> (raw)
In-Reply-To: <507FA595.4020507@freescale.com>
On Thu, Oct 18, 2012 at 02:45:41PM +0800, Huang Shijie wrote:
> 于 2012年10月18日 14:18, Vinod Koul 写道:
>> Why cant you do start (prepare clock etc) when you submit the descriptor
>> to dmaengine. Can be done in tx_submit callback.
>> Similarly remove the clock when dma transaction gets completed.
> I ever thought this method too.
>
> But it will become low efficient in the following case:
>
> Assuming the gpmi-nand driver has to read out 1024 pages in one
> _SINGLE_ read operation.
> The gpmi-nand will submit the descriptor to dmaengine per page. So with
> your method,
> the system will repeat the enable/disable dma clock 1024 time. At every
> enable/disable dma clock,
> the system has to enable the clock chain and it's parents ...
And what if you stop using clk_prepare_enable(), and prepare the clock
when the channel is requested and only use clk_enable() in the tx_submit
method?
next prev parent reply other threads:[~2012-10-18 8:52 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-18 5:32 [PATCH] dma: add new DMA control commands Huang Shijie
2012-10-18 6:18 ` Vinod Koul
2012-10-18 6:45 ` Huang Shijie
[not found] ` <507FA595.4020507-KZfg59tc24xl57MIdRCFDg@public.gmane.org>
2012-10-18 7:14 ` Marek Vasut
2012-10-18 7:49 ` Huang Shijie
[not found] ` <507FB495.7050104-KZfg59tc24xl57MIdRCFDg@public.gmane.org>
2012-10-18 8:16 ` Marek Vasut
2012-10-18 8:29 ` Huang Shijie
2012-11-09 15:29 ` Artem Bityutskiy
2012-10-18 8:49 ` Huang Shijie
[not found] ` <507FC290.10205-KZfg59tc24xl57MIdRCFDg@public.gmane.org>
2012-10-18 8:49 ` Marek Vasut
2012-10-18 9:13 ` Huang Shijie
[not found] ` <507FC827.40601-KZfg59tc24xl57MIdRCFDg@public.gmane.org>
2012-10-18 10:51 ` Marek Vasut
[not found] ` <201210181251.15116.marex-ynQEQJNshbs@public.gmane.org>
2012-10-18 15:11 ` Huang Shijie
2012-10-18 8:52 ` Russell King - ARM Linux [this message]
[not found] ` <20121018085208.GR21164-l+eeeJia6m9vn6HldHNs0ANdhmdF6hFW@public.gmane.org>
2012-10-18 9:10 ` Huang Shijie
2012-10-18 9:29 ` Jassi Brar
2012-10-18 15:18 ` Huang Shijie
2012-10-18 15:25 ` Jassi Brar
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20121018085208.GR21164@n2100.arm.linux.org.uk \
--to=linux@arm.linux.org.uk \
--cc=alsa-devel@alsa-project.org \
--cc=artem.bityutskiy@linux.intel.com \
--cc=b32955@freescale.com \
--cc=ben-linux@fluff.org \
--cc=broonie@opensource.wolfsonmicro.com \
--cc=cjb@laptop.org \
--cc=djbw@fb.com \
--cc=dwmw2@infradead.org \
--cc=khali@linux-fr.org \
--cc=linux-arm-kernel@lists.infradead.org \
--cc=linux-i2c@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-mmc@vger.kernel.org \
--cc=linux-mtd@lists.infradead.org \
--cc=lrg@ti.com \
--cc=marex@denx.de \
--cc=perex@perex.cz \
--cc=shawn.guo@linaro.org \
--cc=shijie8@gmail.com \
--cc=tiwai@suse.de \
--cc=vinod.koul@linux.intel.com \
--cc=w.sang@pengutronix.de \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).