ARM: mvebu: drop pointless check for coherency_base

The MMU off code path in ll_get_coherency_base() attempts to decide
whether the coherency fabric is mapped by testing the value of
coherency_base, which carries its virtual address if its mapped, and
0x0 otherwise.

However, what the code actually does is take the virtual address of
the coherency_base symbol, and compare it with 0x0, which are never
equal, and so the branch is never taken. In fact, with the MMU off,
dereferencing the VA of coherency_base is not possible to begin with,
nor can its value be relied upon with the MMU off since it is not
cleaned to the Dcache as is done with coherency_phys_base in
armada_370_coherency_init().

Instead, the value of coherency_phys_base is returned, which results
in the correct behavior since it will be 0x0 as well if the coherency
fabric is not mapped, and it is accessible with the MMU off. So just
drop the comparison and the branch.

Fixes: 30cdef97107370a7 ("ARM: mvebu: make the coherency_ll.S functions work with no coherency fabric")
Cc: Thomas Petazzoni <thomas.petazzoni@bootlin.com>
Cc: Jason Cooper <jason@lakedaemon.net>
Cc: Andrew Lunn <andrew@lunn.ch>
Cc: Gregory CLEMENT <gregory.clement@bootlin.com>
Cc: Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Gregory CLEMENT <gregory.clement@bootlin.com>

diff --git a/arch/arm/mach-mvebu/coherency_ll.S b/arch/arm/mach-mvebu/coherency_ll.S
index 2d962fe488210d309f050e7387bc7f1812210d3f..a3a64bf972507b3c311844fce4838aaed4446168 100644 (file)
--- a/arch/arm/mach-mvebu/coherency_ll.S
+++ b/arch/arm/mach-mvebu/coherency_ll.S
@@ -35,13 +35,8 @@ ENTRY(ll_get_coherency_base)
 
        /*
         * MMU is disabled, use the physical address of the coherency
-        * 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.
+        * base address, (or 0x0 if the coherency fabric is not mapped)
         */
-       ldr     r1, =coherency_base
-       cmp     r1, #0
-       beq     2f
        adr     r1, 3f
        ldr     r3, [r1]
        ldr     r1, [r1, r3]