On Wed, Sep 07, 2011 at 04:41:32PM +0100, Catalin Marinas wrote: > On 1 September 2011 13:49, Russell King - ARM Linux > <linux@xxxxxxxxxxxxxxxx> wrote: > > Add a dsb after the isb to ensure that the previous writes to the > > CP15 registers take effect before we enable the MMU. > > > > Signed-off-by: Russell King <rmk+kernel@xxxxxxxxxxxxxxxx> > > --- > > arch/arm/mm/proc-v7.S | 1 + > > 1 files changed, 1 insertions(+), 0 deletions(-) > > > > diff --git a/arch/arm/mm/proc-v7.S b/arch/arm/mm/proc-v7.S > > index dec72ee..a773f4e 100644 > > --- a/arch/arm/mm/proc-v7.S > > +++ b/arch/arm/mm/proc-v7.S > > @@ -255,6 +255,7 @@ ENTRY(cpu_v7_do_resume) > > mcr p15, 0, r4, c10, c2, 0 @ write PRRR > > mcr p15, 0, r5, c10, c2, 1 @ write NMRR > > isb > > + dsb > > Isn't an ISB enough here? We usually have the DSB for some background > operations like cache maintenance. That depends whether you're including the effects of the cache maintanence instructions in this. The ARM ARM tells me that a DSB is required to ensure that all cache maintanence is issued before the dsb is complete at the point that the dsb is executed. So for architectural compliance, yes, a dsb is required. The isb is also required to ensure that instruction cache maintanence is properly visible. -- 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
