Hi Vikram, Nishanth, Richard,
a few comments on this:
On Tue, 20 Oct 2009, Vikram Pandita wrote:
> Add bits for future expansion of omap_chip_id type field.
> This is needed to accomodate 3630ES1 chip id which is bit10
...
> diff --git a/arch/arm/plat-omap/include/plat/cpu.h b/arch/arm/plat-omap/include/plat/cpu.h
> index 7cb0556..922bf1c 100644
> --- a/arch/arm/plat-omap/include/plat/cpu.h
> +++ b/arch/arm/plat-omap/include/plat/cpu.h
> @@ -45,7 +45,7 @@ int omap_type(void);
>
> struct omap_chip_id {
> u8 oc;
> - u8 type;
> + u32 type;
> };
Just wanted to understand the motivation for using the u32.
Earlier in the life of these patches, two comments were mentioned: the
desire to 'futureproof' and the desire to reserve space for other
34xx-family parts.
Regarding 'futureproofing:' that's part of the reason that a separate
struct was defined for this: to prevent code that uses it from depending
on the size of the type. (Originally it was a typedef, but Linus hates
typedefs...) So it shouldn't matter how big or small the type is here, as
long as it can handle all of the bits allocated for it.
Also mentioned was the idea of reserving space for other 34xx-family
chips. I'd suggest simply renumbering the bits when and if those versions
appear. Code that uses the omap_chip_id system should always use the
macros (e.g. CHIP_IS_OMAP3430) and not encode separate bit shift values,
so renumbering should be completely safe and transparent for core code.
Module code shouldn't be using the omap_chip code, it's for core usage
only.
So, since only one bit is being added, why not continue the use of the u8?
Then when the next bits need to be added, the type can be expanded at that
point, and the bits renumbered if necessary. This should be a completely
transparent operation for code that uses it. Vikram's original patch:
http://patchwork.kernel.org/patch/54847/
should be fine.
Or am I missing something?
- Paul
--
To unsubscribe from this list: send the line "unsubscribe linux-omap" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
