ioremap_cached in drivers/mtd/maps ?

ioremap_cached in drivers/mtd/maps ?

[Steven Scholz]

Hi there,

it looks like only lubbock-flash.c is using ioremap_cached().

Can I use ioremap_cached() with normal NOR flashes?
Is it only for DMA transfer from/to flash?
Does it improve something when using JFFS2?
What do I have to consider? .inval_cache function?

Thanks a million!

-- 
Steven Scholz
imc Measurement & Control

Re: ioremap_cached in drivers/mtd/maps ?

[Ben Dooks]

On Mon, Feb 21, 2005 at 09:16:26AM +0100, Steven Scholz wrote:
> Hi there,
> 
> it looks like only lubbock-flash.c is using ioremap_cached().
> 
> Can I use ioremap_cached() with normal NOR flashes?
> Is it only for DMA transfer from/to flash?

you could use it for such, but it also allows an cached
area for flash read, which makes it faster to execute
code from.

> Does it improve something when using JFFS2?
> What do I have to consider? .inval_cache function?

It allows the mapping driver to have a seperate read-only
cached area, the .inval_cache function is needed to flush
this area when writes happen to the un-cached area.

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

  'a smiley only costs 4 bytes'

Re: ioremap_cached in drivers/mtd/maps ?

[Nicolas Pitre]

On Mon, 21 Feb 2005, Steven Scholz wrote:

> Hi there,
> 
> it looks like only lubbock-flash.c is using ioremap_cached().

sa1100-flash could be using it as well.

> Can I use ioremap_cached() with normal NOR flashes?

Yes.

> Is it only for DMA transfer from/to flash?

>From flash only.

> Does it improve something when using JFFS2?

Much improved read throughput.

> What do I have to consider? .inval_cache function?

Yep.


Nicolas