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From: Kevin Krakauer <krakauer@google.com>
To: fenghua.yu@intel.com, dave.jiang@intel.com
Cc: dmaengine@vger.kernel.org
Subject: idxd: shared workqueues and dmaengine
Date: Wed, 26 Mar 2025 17:05:07 -0700	[thread overview]
Message-ID: <Z-SWM-F0O9XU1zqp@google.com> (raw)

Hey, I'm trying to use idxd inside the kernel via dmaengine. I'm
attempting to get shared work queues (SWQs) via dma_find_channel(),
which stubbornly returns NULL.

After a lot of printk-ing, I finally ran across DMA_PRIVATE. I also
found [1] and saw that DMA_PRIVATE is also set in the idxd driver since
c06e424be5f51844 ("dmaengine: idxd: set DMA channel to be private").

It seems like this forces use of dma_request_channel(). But I believe
the idea behind SWQs is that they don't have to be exclusively owned.

Is there a way to use SWQs via dma_find_channel()? dma_request_channel()
seems like overkill, as the point of SWQs is to not be exclusive. Also a
good chance I'm missing something basic here :)

Thanks!
Kevin

1 - https://lore.kernel.org/dmaengine/9714cb6c-8b37-4fc6-bb09-a1fb4a5bb1b8@intel.com/#R

             reply	other threads:[~2025-03-27  0:05 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-03-27  0:05 Kevin Krakauer [this message]
2025-03-27  0:15 ` idxd: shared workqueues and dmaengine Dave Jiang
2025-03-27 18:56   ` Kevin Krakauer
2025-03-27 20:22     ` Dave Jiang

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