[PATCH 1/2] Documentation: arm: early_ioremap

[rob@landley.net (Rob Landley)]

On 06/25/2013 12:46:40 PM, Leif Lindholm wrote:
> This patch provides documentation of the early_ioremap()  
> functionality,
> including its implementation and usage instructions.
> 
> Signed-off-by: Leif Lindholm <leif.lindholm@linaro.org>
> ---
>  Documentation/arm/00-INDEX          |    2 ++
>  Documentation/arm/early_ioremap.txt |   12 ++++++++++++
>  2 files changed, 14 insertions(+)
>  create mode 100644 Documentation/arm/early_ioremap.txt
> 
> diff --git a/Documentation/arm/00-INDEX b/Documentation/arm/00-INDEX
> index 36420e1..4978456 100644
> --- a/Documentation/arm/00-INDEX
> +++ b/Documentation/arm/00-INDEX
> @@ -24,6 +24,8 @@ SPEAr
>  	- ST SPEAr platform Linux Overview
>  VFP/
>  	- Release notes for Linux Kernel Vector Floating Point support  
> code
> +early_ioremap.txt
> +	- documentation of the early_ioremap() functionality
>  empeg/
>  	- Ltd's Empeg MP3 Car Audio Player
>  mem_alignment
> diff --git a/Documentation/arm/early_ioremap.txt  
> b/Documentation/arm/early_ioremap.txt
> new file mode 100644
> index 0000000..178f791
> --- /dev/null
> +++ b/Documentation/arm/early_ioremap.txt
> @@ -0,0 +1,12 @@
> +early_ioremap() and early_iounmap() rovide a mechanism for  
> temporarily mapping

Typo: provide

> +in small blocks of memory, identified by their physical address,  
> into the
> +fixmap virtual address block before paging_init() has been called  
> and more
> +flexible mapping functions are available.
> +
> +Due to its direct method, it also gets around potential need for  
> special
> +handling of regions that end up in highmem.
> +
> +It supports up to 7 simultaneously mapped regions of up to 128KB  
> each.
> +All regions are mapped as non-shareable device memory.
> +
> +Specify 'early_ioremap_debug' on the kernel commandline for verbose  
> output.
> --
> 1.7.10.4

Minor quibble: this explains what it does, but nothing about how to use  
it. Do these mappings persist if you don't unmap them, or does  
paging_init() clear them?

Oh well:

Acked-by: Rob Landley <rob@landley.net>

Rob