Re: [PATCH 2/2] arcmsr: code cleanup and some corrections

[Tomas Henzl <thenzl@redhat.com>]

Hi Nick,
again thanks for your response in the 
'arcmsr: code cleanup and some corrections' thread.

Let us find a resolution here too.
Is the original patch fine for you, or do you prefer not to take it?

Tomas


> On 02/18/2011 02:04 AM, FUJITA Tomonori wrote:
>   
>> On Thu, 17 Feb 2011 16:05:37 +0100
>> Tomas Henzl <thenzl@redhat.com> wrote:
>>
>>   
>>     
>>> the discussion is mostly if 'dma_alloc_coherent' 
>>> ...
>>> dma_coherent = dma_alloc_coherent(&pdev->dev, acb->uncache_size, &dma_coherent_handle, GFP_KERNEL);
>>> ...
>>> returns a page address - dma_coherent with last, I think five bits, zeroed.
>>> Could you help us with that?
>>>     
>>>       
>> Documentation/DMA-API-HOWTO.txt is not clear enough?
>>
>> =
>> dma_alloc_coherent returns two values: the virtual address which you
>> can use to access it from the CPU and dma_handle which you pass to the
>> card.
>>
>> The cpu return address and the DMA bus master address are both
>> guaranteed to be aligned to the smallest PAGE_SIZE order which
>> is greater than or equal to the requested size.  This invariant
>> exists (for example) to guarantee that if you allocate a chunk
>> which is smaller than or equal to 64 kilobytes, the extent of the
>> buffer you receive will not cross a 64K boundary.
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>>     
> It's clear enough I think, I asked this question because Nick doesn't
> have a "100% confidence in that.". So I wanted a help to convince him.
>
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