From: clemens@ladisch.de (Clemens Ladisch)
To: linux-arm-kernel@lists.infradead.org
Subject: About dma_sync_single_for_{cpu,device}
Date: Tue, 31 Jul 2012 08:59:21 +0200 [thread overview]
Message-ID: <50178249.7090306@ladisch.de> (raw)
In-Reply-To: <20120731064557.GA4676@gobelin>
Karl Beldan wrote:
> To tx a chunk of data from the SoC => network device, we :
> - prepare a buffer with a leading header embedding a pattern,
> - trigger the xfer and wait for an irq
> // The device updates the pattern and then triggers an irq
> - upon irq we check the pattern for the xfer completion
>
> I was expecting the following to work:
> addr = dma_map_single(dev, buffer, size, DMA_TO_DEVICE);
Of both the CPU and the device write to the buffer, you must use
DMA_BIDIRECTIONAL.
Regards,
Clemens
WARNING: multiple messages have this Message-ID (diff)
From: Clemens Ladisch <clemens@ladisch.de>
To: Karl Beldan <karl.beldan@gmail.com>
Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org
Subject: Re: About dma_sync_single_for_{cpu,device}
Date: Tue, 31 Jul 2012 08:59:21 +0200 [thread overview]
Message-ID: <50178249.7090306@ladisch.de> (raw)
In-Reply-To: <20120731064557.GA4676@gobelin>
Karl Beldan wrote:
> To tx a chunk of data from the SoC => network device, we :
> - prepare a buffer with a leading header embedding a pattern,
> - trigger the xfer and wait for an irq
> // The device updates the pattern and then triggers an irq
> - upon irq we check the pattern for the xfer completion
>
> I was expecting the following to work:
> addr = dma_map_single(dev, buffer, size, DMA_TO_DEVICE);
Of both the CPU and the device write to the buffer, you must use
DMA_BIDIRECTIONAL.
Regards,
Clemens
next prev parent reply other threads:[~2012-07-31 6:59 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-07-30 20:24 About dma_sync_single_for_{cpu,device} karl.beldan
2012-07-30 20:34 ` karl.beldan
2012-07-31 6:45 ` Karl Beldan
2012-07-31 6:45 ` Karl Beldan
2012-07-31 6:59 ` Clemens Ladisch [this message]
2012-07-31 6:59 ` Clemens Ladisch
2012-07-31 7:27 ` Karl Beldan
2012-07-31 7:27 ` Karl Beldan
2012-07-31 7:34 ` Clemens Ladisch
2012-07-31 7:34 ` Clemens Ladisch
2012-07-31 8:30 ` Karl Beldan
2012-07-31 8:30 ` Karl Beldan
2012-07-31 9:09 ` Russell King - ARM Linux
2012-07-31 9:09 ` Russell King - ARM Linux
2012-07-31 19:31 ` Karl Beldan
2012-07-31 19:31 ` Karl Beldan
2012-07-31 20:08 ` Russell King - ARM Linux
2012-07-31 20:08 ` Russell King - ARM Linux
2012-08-01 6:50 ` Karl Beldan
2012-08-01 6:50 ` Karl Beldan
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