linux-kernel - Re: [PATCH] spi: omap2-mcspi: In case of dma errors fall back to pio

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Message-ID: <20120807122125.GY8468@arwen.pp.htv.fi>
Date:	Tue, 7 Aug 2012 15:21:26 +0300
From:	Felipe Balbi <balbi@...com>
To:	Tony Lindgren <tony@...mide.com>
Cc:	Shubhrajyoti <shubhrajyoti@...com>,
	spi-devel-general@...ts.sourceforge.net,
	linux-omap@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] spi: omap2-mcspi: In case of dma errors fall back to pio

Hi,

On Tue, Aug 07, 2012 at 05:02:27AM -0700, Tony Lindgren wrote:
> * Shubhrajyoti <shubhrajyoti@...com> [120807 04:21]:
> > On Tuesday 07 August 2012 01:17 PM, Tony Lindgren wrote:
> > >>  };
> > > Don't you need to check separately for rx and tx dma? There's a slight
> > > chance that you get a channel for one but not for the other..
> > In that case I treat it as non usable and fall back to pio.
> 
> OK that should work too.
>  
> > Are you suggesting that let one channel be dma and only the failed one pio?
> 
> I guess both are doable. For reduced CPU load using DMA where possible
> of course is the best way to go.

indeed. if you can get DMA for TX but not for RX, then at least TX can
go via DMA ;-)

-- 
balbi

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