Hi Thomas, On 27/10/2014 16:32, Thomas Petazzoni wrote: > The ll_add_cpu_to_smp_group(), ll_enable_coherency() and > ll_disable_coherency() are used on Armada XP to control the coherency > fabric. However, they make the assumption that the coherency fabric is > always available, which is currently a correct assumption but will no > longer be true with a followup commit that disables the usage of the > coherency fabric when the conditions are not met to use it. > > Therefore, this commit modifies those functions so that they check the > return value of ll_get_coherency_base(), and if the return value is 0, > they simply return without configuring anything in the coherency > fabric. > > The ll_get_coherency_base() function is also modified to properly > return 0 when the function is called with the MMU disabled. In this > case, it normally returns the physical address of the coherency > fabric, but we now check if the virtual address is 0, and if that's > case, return a physical address of 0 to indicate that the coherency > fabric is not enabled. > > Signed-off-by: Thomas Petazzoni <thomas.petazzoni@xxxxxxxxxxxxxxxxxx> > Cc: <stable@xxxxxxxxxxxxxxx> # v3.8+ > --- > arch/arm/mach-mvebu/coherency_ll.S | 21 +++++++++++++++++++-- > 1 file changed, 19 insertions(+), 2 deletions(-) > > diff --git a/arch/arm/mach-mvebu/coherency_ll.S b/arch/arm/mach-mvebu/coherency_ll.S > index f5d881b..0ed07c3 100644 > --- a/arch/arm/mach-mvebu/coherency_ll.S > +++ b/arch/arm/mach-mvebu/coherency_ll.S > @@ -24,7 +24,10 @@ > #include <asm/cp15.h> > > .text > -/* Returns the coherency base address in r1 (r0 is untouched) */ > +/* > + * Returns the coherency base address in r1 (r0 is untouched), or 0 if > + * the coherency fabric is not enabled. > + */ > ENTRY(ll_get_coherency_base) > mrc p15, 0, r1, c1, c0, 0 > tst r1, #CR_M @ Check MMU bit enabled > @@ -32,8 +35,13 @@ ENTRY(ll_get_coherency_base) > > /* > * MMU is disabled, use the physical address of the coherency > - * base address. > + * base address. However, if the coherency fabric isn't mapped > + * (i.e its virtual address is zero), it means coherency is > + * not enabled, so we return 0. > */ > + ldr r1, =coherency_base > + cmp r1, #0 > + beq 2f > adr r1, 3f > ldr r3, [r1] > ldr r1, [r1, r3] > @@ -85,6 +93,9 @@ ENTRY(ll_add_cpu_to_smp_group) > */ > mov r0, lr > bl ll_get_coherency_base > + /* Bail out if the coherency is not enabled */ > + cmp r1, #0 > + moveq pc, r0 Since the commit "6ebbf2ce437b33022d30badd49dc94d33ecfa498: ARM: convert all "mov.* pc, reg" to "bx reg" for ARMv6+", you should use "reteq r0" instead of "moveq pc, r0". > bl ll_get_coherency_cpumask > mov lr, r0 > add r0, r1, #ARMADA_XP_CFB_CFG_REG_OFFSET > @@ -107,6 +118,9 @@ ENTRY(ll_enable_coherency) > */ > mov r0, lr > bl ll_get_coherency_base > + /* Bail out if the coherency is not enabled */ > + cmp r1, #0 > + moveq pc, r0 Same here > bl ll_get_coherency_cpumask > mov lr, r0 > add r0, r1, #ARMADA_XP_CFB_CTL_REG_OFFSET > @@ -131,6 +145,9 @@ ENTRY(ll_disable_coherency) > */ > mov r0, lr > bl ll_get_coherency_base > + /* Bail out if the coherency is not enabled */ > + cmp r1, #0 > + moveq pc, r0 and same here > bl ll_get_coherency_cpumask > mov lr, r0 > add r0, r1, #ARMADA_XP_CFB_CTL_REG_OFFSET > Besides this small changes: Acked-by: Gregory CLEMENT <gregory.clement@xxxxxxxxxxxxxxxxxx> Thanks, Gregory -- Gregory Clement, Free Electrons Kernel, drivers, real-time and embedded Linux development, consulting, training and support. http://free-electrons.com -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html