linux-kernel - Re: [PATCH] dmaengine: dmatest: prevent using swiotlb buffer with nobounce parameter

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Date:   Mon, 11 Dec 2023 20:34:33 +0530
From:   Vinod Koul <vkoul@...nel.org>
To:     Amelie Delaunay <amelie.delaunay@...s.st.com>
Cc:     dmaengine@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] dmaengine: dmatest: prevent using swiotlb buffer with
 nobounce parameter


On Fri, 24 Nov 2023 17:02:35 +0100, Amelie Delaunay wrote:
> Source and destination data buffers are allocated with GPF_KERNEL flag.
> It means that, if the DDR is more than 2GB, buffers can be allocated above
> the 32-bit addressable space. In this case, and if the dma controller is
> only 32-bit compatible, swiotlb bounce buffer, located in the 32-bit
> addressable space, is used and introduces a memcpy.
> 
> To prevent this extra memcpy, due to swiotlb bounce buffer use because
> source or destination data buffer is allocated above the 32-bit addressable
> space, force source and destination data buffers allocation with GPF_DMA
> instead, when nobounce parameter is true.
> 
> [...]

Applied, thanks!

[1/1] dmaengine: dmatest: prevent using swiotlb buffer with nobounce parameter
      commit: 70f008fb3ea9bd2e6727eebc858405acd49a212b

Best regards,
-- 
~Vinod