From: "Russell King (Oracle)" <linux@armlinux.org.uk>
To: Li Chen <me@linux.beauty>
Cc: dmaengine <dmaengine@vger.kernel.org>,
linux-arm-kernel <linux-arm-kernel@lists.infradead.org>,
linux-kernel <linux-kernel@vger.kernel.org>,
Arnd Bergmann <arnd@arndb.de>
Subject: Re: Should dma_map_single take the dma controller or its consumer as an argument?
Date: Wed, 28 Jun 2023 12:02:47 +0100 [thread overview]
Message-ID: <ZJwTV59xRlUBit+N@shell.armlinux.org.uk> (raw)
In-Reply-To: <18901a6cbf0.c9e3e099688173.4166132371304083225@linux.beauty>
On Wed, Jun 28, 2023 at 06:57:35PM +0800, Li Chen wrote:
> Hi all,
>
> I recently encountered an issue where the dma_mask was set in the DMA controller's driver, but the consumer peripheral driver didn't set its own dma_mask.
It should always take the device that is *actually* performing the DMA,
since that is the device that has restrictions on what addresses can be
accessed, etc.
Devices that "consume" the data from a DMA controller don't access
memory - they are merely the targets, and they can't on their own access
host memory. Therefore, their dma mask _should_ be irrelevant.
--
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next prev parent reply other threads:[~2023-06-28 11:03 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-06-28 10:57 Should dma_map_single take the dma controller or its consumer as an argument? Li Chen
2023-06-28 11:02 ` Russell King (Oracle) [this message]
2023-06-28 11:16 ` Li Chen
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