Subject: Re: [PATCH] powerpc: Fix PowerPC 750CL CPU features

From: Segher Boessenkool <[email-masked]>
Date: Thu, 12 Apr 2007 18:41:29 +0200

> PowerPC 750CL has high BATs.  The patch below sets cpu_features to 
> match that.
> Without it, the original firmware mappings in the high BATs aren't 
> cleared
> which can cause "odd" address translations to occur.

> -		.cpu_features		= CPU_FTRS_750,
> +		.cpu_features		= CPU_FTRS_750GX,

The difference between these two is

#define CPU_FTRS_750GX  (CPU_FTR_DUAL_PLL_750FX | CPU_FTR_HAS_HIGH_BATS)
#define CPU_FTRS_750    (CPU_FTR_COMMON)

750GX excludes COMMON, which seems like a bug.  With
your change, 750CL uses DUAL_PLL_750FX; does it actually
have that feature?

Either way, it seems a good idea to create a CPU_FTRS_750CL,
the CL is an evolution of the CX, not the FX/GX (in name
at least, dunno about the gory details).

> -		.cpu_setup		= __setup_cpu_750cx,
> +		.cpu_setup		= __setup_cpu_750fx,

Same thing here.  Are you sure 750CL doesn't need
the NAP workaround?  [Is anyone sure the 750CX
actually needs it -- the comment in cpu_setup_6xx.S
doesn't instill much confidence.]

Segher