From: "chenxiang (M)" <chenxiang66@hisilicon.com>
To: Will Deacon <will@kernel.org>
Cc: iommu@lists.linux-foundation.org, robin.murphy@arm.com
Subject: Re: [PATCH] iommu/dma: Fix a typo in a comment
Date: Thu, 18 Mar 2021 17:55:46 +0800 [thread overview]
Message-ID: <c378734f-33d5-1426-fa41-2bd8064ceec4@hisilicon.com> (raw)
In-Reply-To: <20210318093410.GA6574@willie-the-truck>
Hi will,
在 2021/3/18 17:34, Will Deacon 写道:
> On Thu, Mar 18, 2021 at 11:21:24AM +0800, chenxiang wrote:
>> From: Xiang Chen <chenxiang66@hisilicon.com>
>>
>> Fix a type "SAC" to "DAC" in the comment of function
>> iommu_dma_alloc_iova().
>>
>> Signed-off-by: Xiang Chen <chenxiang66@hisilicon.com>
>> ---
>> drivers/iommu/dma-iommu.c | 2 +-
>> 1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
>> index af765c8..3bc17ee 100644
>> --- a/drivers/iommu/dma-iommu.c
>> +++ b/drivers/iommu/dma-iommu.c
>> @@ -443,7 +443,7 @@ static dma_addr_t iommu_dma_alloc_iova(struct iommu_domain *domain,
>> if (domain->geometry.force_aperture)
>> dma_limit = min(dma_limit, (u64)domain->geometry.aperture_end);
>>
>> - /* Try to get PCI devices a SAC address */
>> + /* Try to get PCI devices a DAC address */
>> if (dma_limit > DMA_BIT_MASK(32) && dev_is_pci(dev))
>> iova = alloc_iova_fast(iovad, iova_len,
>> DMA_BIT_MASK(32) >> shift, false);
> This doesn't look like a typo to me... Please explain.
I think it means double-address cycle(DAC), and in LLD3 452 page, there
is a description about it "PCI double-address cycle mappings Normally,
the DMA support layer works with 32-bit bus addresses, possibly
restricted by a specific device’s DMA mask. The PCI bus, however, also
supports a 64-bit addressing mode, the double-address cycle (DAC)."
Please point it out if i am wrong :)
Best Regards,
chenxiang
>
> Will
>
> .
>
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next prev parent reply other threads:[~2021-03-18 9:55 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-18 3:21 [PATCH] iommu/dma: Fix a typo in a comment chenxiang
2021-03-18 9:34 ` Will Deacon
2021-03-18 9:55 ` chenxiang (M) [this message]
2021-03-18 11:01 ` Robin Murphy
2021-03-19 1:02 ` chenxiang (M)
2021-03-19 11:02 ` Robin Murphy
2021-03-22 1:01 ` chenxiang (M)
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