From: Christoph Hellwig <hch@infradead.org>
To: Cai Huoqing <caihuoqing@baidu.com>
Cc: hch@infradead.org, Michael Cyr <mikecyr@linux.ibm.com>,
"James E.J. Bottomley" <jejb@linux.ibm.com>,
"Martin K. Petersen" <martin.petersen@oracle.com>,
linux-scsi@vger.kernel.org, target-devel@vger.kernel.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2] scsi: ibmvscsi_tgt: Use dma_alloc_noncoherent() instead of get_zeroed_page/dma_map_single()
Date: Tue, 12 Oct 2021 06:20:32 +0100 [thread overview]
Message-ID: <YWUbIBna0NAOJu62@infradead.org> (raw)
In-Reply-To: <20211012032110.2224-1-caihuoqing@baidu.com>
On Tue, Oct 12, 2021 at 11:21:09AM +0800, Cai Huoqing wrote:
> Replacing get_zeroed_page/free_page/dma_map_single/dma_unmap_single()
> with dma_alloc_noncoherent/dma_free_noncoherent() helps to reduce
> code size, and simplify the code, and the hardware keep DMA coherent
> itself.
It might also be worth to mention that this also avoids potential
bounce buffering. Although for pseries vio devices this probably can't
happen anyway.
> + vscsi->cmd_q.base_addr = dma_alloc_noncoherent(&vdev->dev, PAGE_SIZE,
> + &vscsi->cmd_q.crq_token,
> + DMA_BIDIRECTIONAL, GFP_KERNEL);
Please avoid the overly long line.
The same comments also apply to the other patch.
next prev parent reply other threads:[~2021-10-12 5:22 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-12 3:21 [PATCH v2] scsi: ibmvscsi_tgt: Use dma_alloc_noncoherent() instead of get_zeroed_page/dma_map_single() Cai Huoqing
2021-10-12 5:20 ` Christoph Hellwig [this message]
2021-10-12 23:37 ` Finn Thain
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