From: Ding Tianhong <dingtianhong@huawei.com>
To: Arnd Bergmann <arnd@arndb.de>
Cc: <linux-arm-kernel@lists.infradead.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Will Deacon <Will.Deacon@arm.com>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
Subject: Re: For the problem when using swiotlb
Date: Thu, 20 Nov 2014 17:21:23 +0800 [thread overview]
Message-ID: <546DB293.1040500@huawei.com> (raw)
In-Reply-To: <2121725.INdNoXW7GO@wuerfel>
On 2014/11/20 17:02, Arnd Bergmann wrote:
> On Thursday 20 November 2014 16:34:29 Ding Tianhong wrote:
>>>
>>> I didn't mean the dma_pfn_offset. The problem is that the of_dma_configure
>>> code currently doesn't look at the mask. As I explained in my reply to
>>> Catalin, it should set the mask to the size of the dma-ranges if that is
>>> 32-bit or smaller, and dma_set_mask should look at the same dma-ranges
>>> property to decide what to set the mask to when a driver asks for a
>>> mask larger than 64-bit.
>>>
>> ok, I think the your reply to catalin is clear, I got it, add a
>> appropriate mask for the dev is
>> reasonable, I think it should be fixed later.
>>
>> But in my case, if I don't use the DMA_CMA, the dma_alloc_coherent
>> should use the swiotlb directly which maximum is 16M,
>> so unless I use the kmalloc otherwise I have no better idea for that.
>
> But if you just change your driver to set the 64-bit DMA mask,
> it will no longer use the swiotlb and work much faster without
> that. You have to do it anyway, even once we fix the architecture
> code.
>
Yes, I did, it is useful, thanks.
> The fix in the architecture code is just required so things don't
> break if you have a 64-bit DMA capable device on a 32-bit bus.
>
> On a related note, we should really fix the network and scsi core
> code not lot just look at PCI_DMA_BUS_IS_PHYS but check the presence
> of an IOMMU for devices that are limited to 32-bit DMA, so we fall
> back to block bounce and lowmem SKB instead of swiotlb for IOMMU-less
> devices.
>
agree.
> Which driver are you using BTW?
>
soc ppe drivers which is not upstream yet, and sas drivers.
> Arnd
Regards
Ding
>
> .
>
next prev parent reply other threads:[~2014-11-20 9:21 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-11-17 11:56 For the problem when using swiotlb Ding Tianhong
2014-11-17 12:18 ` Arnd Bergmann
2014-11-17 18:09 ` Catalin Marinas
2014-11-19 3:17 ` Ding Tianhong
2014-11-19 8:45 ` Arnd Bergmann
2014-11-19 11:29 ` Catalin Marinas
2014-11-19 12:48 ` Arnd Bergmann
2014-11-19 15:46 ` Catalin Marinas
2014-11-19 15:56 ` Arnd Bergmann
2014-11-21 11:06 ` Catalin Marinas
2014-11-21 11:26 ` Arnd Bergmann
2014-11-21 11:36 ` Catalin Marinas
2014-11-21 12:27 ` Arnd Bergmann
2014-11-20 2:57 ` Ding Tianhong
2014-11-20 7:40 ` Arnd Bergmann
2014-11-20 8:34 ` Ding Tianhong
2014-11-20 9:02 ` Arnd Bergmann
2014-11-20 9:21 ` Ding Tianhong [this message]
2014-11-21 9:35 ` Catalin Marinas
2014-11-21 10:32 ` Catalin Marinas
2014-11-21 12:48 ` Arnd Bergmann
2014-11-21 16:57 ` Catalin Marinas
2014-11-21 17:04 ` Arnd Bergmann
2014-11-21 17:51 ` Catalin Marinas
2014-11-21 18:09 ` Catalin Marinas
2014-11-24 20:12 ` Arnd Bergmann
2014-11-25 10:58 ` Catalin Marinas
2014-11-25 11:29 ` Russell King - ARM Linux
2014-11-25 12:23 ` Catalin Marinas
2014-11-27 2:36 ` Ding Tianhong
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