[PATCH 3/4 v2] ARM: L2 : Errata 588369: Clean & Invalidate do not invalidate clean lines

[linux@arm.linux.org.uk (Russell King - ARM Linux)]

On Thu, Dec 17, 2009 at 06:30:32PM +0530, Santosh Shilimkar wrote:
> +config PL310_ERRATA_588369
> +	bool "Clean & Invalidate maintenance operations do not invalidate clean lines"
> +	depends on CACHE_L2X0 && ARCH_OMAP4
> +	default n

default n is the default anyway, so its redundant to specify it.

> +#ifdef CONFIG_PL310_ERRATA_588369
> +static void debug_writel(unsigned long val)
> +{
> +	/*
> +	 * Texas Instrument secure monitor api to modify the PL310
> +	 * Debug Control Register. R0 = val
> +	 */
> +	__asm__ __volatile__(
> +	"stmfd r13!, {r4-r8}\n"
> +	"ldr r12, =0x100\n"
> +	"dsb\n"
> +	"smc\n"
> +	"ldmfd r13!, {r4-r8}");

Just tell the compiler that r4 to r8 are clobbered - then it'll save and
restore them itself.  Also, you can't guarantee that r0 will contain the
value unless you explicitly pass it in.  IOW:

	register unsigned long r0 asm("r0") = val;

	asm volatile(
	__asmeq(%0, r0)
	"..."
	: : "r" (r0)
	: "r4", "r5", "r6", "r7", "r8");

The use of asmeq will also ensure that '%0' is indeed r0 - some gcc
versions are buggy.

As I've said before, your patch is fine for the current version, but
not for the other cache-l2x0 changes.