From: Christoph Hellwig <hch@infradead.org>
To: John Garry <john.g.garry@oracle.com>
Cc: Damien Le Moal <dlemoal@kernel.org>,
Yihang Li <liyihang9@huawei.com>,
yanaijie@huawei.com, jejb@linux.ibm.com,
martin.petersen@oracle.com, chenxiang66@hisilicon.com,
linux-scsi@vger.kernel.org, linux-kernel@vger.kernel.org,
linuxarm@huawei.com, prime.zeng@huawei.com,
yangxingui@huawei.com
Subject: Re: [PATCH v2] scsi: libsas: Allocation SMP request is aligned to ARCH_DMA_MINALIGN
Date: Wed, 27 Mar 2024 23:35:19 -0700 [thread overview]
Message-ID: <ZgUPpwhkE9bRwHec@infradead.org> (raw)
In-Reply-To: <0ba9914d-7060-498a-beac-2b19770e1963@oracle.com>
On Tue, Mar 26, 2024 at 01:32:09PM +0000, John Garry wrote:
> > > + u8 *p;
> > > +
> > > + size = ALIGN(size, ARCH_DMA_MINALIGN);
>
>
> If this is a hisi_sas requirement, then why use ARCH_DMA_MINALIGN and not
> 16B as minimum alignment?
>
> Or are we really talking about an arch requirement?
One thing is that we should never allocate unaligned memory for
anything DMA mapped, or data will be corrupted by non-coherent DMA.
So ARCH_DMA_MINALIGN needs to be here. If specific hardware has
further requirements we'll need to communicated it through a field
or op vector.
next prev parent reply other threads:[~2024-03-28 6:35 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-26 12:43 [PATCH v2] scsi: libsas: Allocation SMP request is aligned to ARCH_DMA_MINALIGN Yihang Li
2024-03-26 13:14 ` Damien Le Moal
2024-03-26 13:32 ` John Garry
2024-03-26 13:40 ` Damien Le Moal
2024-03-28 6:35 ` Christoph Hellwig [this message]
2024-03-28 6:59 ` Yihang Li
2024-03-28 7:23 ` Damien Le Moal
2024-03-28 7:29 ` Christoph Hellwig
2024-03-28 7:36 ` Damien Le Moal
2024-03-28 7:45 ` Christoph Hellwig
2024-03-28 8:00 ` Yihang Li
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