From: arnd@arndb•de (Arnd Bergmann)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH] the eDMA support for the LPUART send driver
Date: Tue, 7 Jan 2014 09:53:51 +0100 [thread overview]
Message-ID: <201401070953.52207.arnd@arndb.de> (raw)
In-Reply-To: <0602455564214ab7986348ea985fc820@BL2PR03MB338.namprd03.prod.outlook.com>
On Tuesday 07 January 2014, Yao Yuan wrote:
> Thanks for your suggestion. It's important for me.
>
> I read the source code for dma_map_single again. I found that both of them(as first argument is
> dma or uart) worked well. But in my code I found that the *sport->port.dev->dma_mask is not
> zero. By contrast the dma_mask for dma device is zero.
Ah, it seems you found two more bugs then ;-)
> You are right. There should be dma device. But I also have a doubt here. Why I find many other
> driver use the first argument here rather than the dma device pointer.
It's a common mistake. Most other linux device driver interfaces require you to pass the
device you are working on, so it's understandable why people come to the wrong conclusion
here.
Arnd
next prev parent reply other threads:[~2014-01-07 8:53 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-12-27 11:24 [PATCH] the eDMA support for the LPUART send driver Yuan Yao
2014-01-05 14:44 ` Arnd Bergmann
2014-01-05 14:50 ` Russell King - ARM Linux
2014-01-07 6:32 ` Yao Yuan
2014-01-07 8:53 ` Arnd Bergmann [this message]
2014-01-07 9:49 ` Yao Yuan
2014-01-06 5:37 ` Shawn Guo
2014-01-07 9:44 ` Yao Yuan
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