Writing to NAND using DMA

Writing to NAND using DMA

[Gaurav Singh]

I am working on an ST Nomadik board with ST 1 GB NAND chip. Have
written a board specific driver and trying to use DMA and JFFS2
filesystem to write data to the NAND .

I have allocated a nand_buffer structure using dma_alloc_coherent and
am using this buffer for reading data.

In case of write however I see that the JFFS2 filesystem has allocated
a wbuf for writing (using kmalloc). Now I have an option of copying
this buffer into a dma able buffer of my own but I feel there should
be a better solution.

What is your view ? Should JFFS2 provide a dma able buffer to write a
NAND page ?

Re: Writing to NAND using DMA

[Ben Dooks]

On Wed, Nov 05, 2008 at 04:49:58PM +0530, Gaurav Singh wrote:
> I am working on an ST Nomadik board with ST 1 GB NAND chip. Have
> written a board specific driver and trying to use DMA and JFFS2
> filesystem to write data to the NAND .
> 
> I have allocated a nand_buffer structure using dma_alloc_coherent and
> am using this buffer for reading data.
> 
> In case of write however I see that the JFFS2 filesystem has allocated
> a wbuf for writing (using kmalloc). Now I have an option of copying
> this buffer into a dma able buffer of my own but I feel there should
> be a better solution.
> 
> What is your view ? Should JFFS2 provide a dma able buffer to write a
> NAND page ?

This discussion came up at CELF, I belive that there is a move to try
and make the mtd interface take only DMA-safe memory since it is not
only JFFS2 that may be using the NAND driver.

-- 
Ben (ben@fluff.org, http://www.fluff.org/)

  'a smiley only costs 4 bytes'