path: root/arch/arm/mach-spear/hotplug.c
diff options
authorRussell King <rmk+kernel@armlinux.org.uk>2018-12-13 14:02:48 +0000
committerRussell King <rmk+kernel@armlinux.org.uk>2019-02-01 22:05:23 +0000
commit6213f70e7c10fd4a01b65bad3826648fc78df8a8 (patch)
treec1296d53776c9668057f570485285754c2424ab5 /arch/arm/mach-spear/hotplug.c
parent70678554c4c40f2cf8de5e7cd53fdd2c73387e51 (diff)
ARM: smp: remove arch-provided "pen_release"
Consolidating the "pen_release" stuff amongst the various SoC implementations gives credence to having a CPU holding pen for secondary CPUs. However, this is far from the truth. Many SoC implementations cargo-cult copied various bits of the pen release implementation from the initial Realview/Versatile Express implementation without understanding what it was or why it existed. The reason it existed is because these are _development_ platforms, and some board firmware is unable to individually control the startup of secondary CPUs. Moreover, they do not have a way to power down or reset secondary CPUs for hot-unplug. Hence, the pen_release implementation was designed for ARM Ltd's development platforms to provide a working implementation, even though it is very far from what is required. It was decided a while back to reduce the duplication by consolidating the "pen_release" variable, but this only made the situation worse - we have ended up with several implementations that read this variable but do not write it - again, showing the cargo-cult mentality at work, lack of proper review of new code, and in some cases a lack of testing. While it would be preferable to remove pen_release entirely from the kernel, this is not possible without help from the SoC maintainers, which seems to be lacking. However, I want to remove pen_release from arch code to remove the credence that having it gives. This patch removes pen_release from the arch code entirely, adding private per-SoC definitions for it instead, and explicitly stating that write_pen_release() is cargo-cult copied and should not be copied any further. Rename write_pen_release() in a similar fashion as well. Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Diffstat (limited to 'arch/arm/mach-spear/hotplug.c')
1 files changed, 3 insertions, 1 deletions
diff --git a/arch/arm/mach-spear/hotplug.c b/arch/arm/mach-spear/hotplug.c
index 12edd1cf8a12..0dd84f609627 100644
--- a/arch/arm/mach-spear/hotplug.c
+++ b/arch/arm/mach-spear/hotplug.c
@@ -16,6 +16,8 @@
#include <asm/cp15.h>
#include <asm/smp_plat.h>
+#include "generic.h"
static inline void cpu_enter_lowpower(void)
unsigned int v;
@@ -57,7 +59,7 @@ static inline void spear13xx_do_lowpower(unsigned int cpu, int *spurious)
for (;;) {
- if (pen_release == cpu) {
+ if (spear_pen_release == cpu) {
* OK, proper wakeup, we're done

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