linux-kernel - Re: [PATCH v2 1/5] dmaengine: add ep93xx DMA support

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Message-ID: <20111122055925.GA15889@mwesterb-mobl.ger.corp.intel.com>
Date:	Tue, 22 Nov 2011 07:59:25 +0200
From:	Mika Westerberg <mika.westerberg@....fi>
To:	Vinod Koul <vinod.koul@...el.com>
Cc:	Rafal Prylowski <prylowski@...asoft.pl>, rmallon@...il.com,
	broonie@...nsource.wolfsonmicro.com, linux-kernel@...r.kernel.org,
	grant.likely@...retlab.ca, hsweeten@...ionengravers.com,
	dan.j.williams@...el.com, lrg@...com,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH v2 1/5] dmaengine: add ep93xx DMA support

On Mon, Nov 21, 2011 at 02:02:06PM +0530, Vinod Koul wrote:
> On Mon, 2011-11-21 at 10:01 +0200, Mika Westerberg wrote:
> > On Mon, Nov 21, 2011 at 08:44:07AM +0100, Rafal Prylowski wrote:
> > > 
> > > I'm calling dma_terminate_all from interrupt. It seems that tasklet_kill is not
> > > allowed to be called from this context.
> > 
> > Ah, right.
> > 
> > One more try - this time we set a flag which prevents the tasktlet from
> > referencing an empty list.

> Rather than this why not actually check for list_empty and process only
> when it is not empty?

I was thinking that it should be an error if the active list is empty when the
tasklet is run.

> Also you should check the return of the ep93xx_dma_get_active() which
> should return NULL if it didn't find anything in active list

Right - if the list is allowed to be empty.

I'll re-check the patch from Rafal. Maybe it's better to adapt with the fact
that dma_terminate_all() can be called in any context any time and modify the
driver accordingly (e.g like you say, return NULL if the list is empty handle
it correctly).
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