On Thu, 03 Apr 2008 17:43:02 -0500
Jerone Young <[EMAIL PROTECTED]> wrote:
> # HG changeset patch
> # User Jerone Young <[EMAIL PROTECTED]>
> # Date 1207262487 18000
> # Node ID 7226bef216680748a50327900572c2fbc3e762b0
> # Parent a5b2aebbc6ebd2439c655f1c047ed7e3c1991ec1
As a complete and unrelated side note to the actual patch, wtf is this
hg stuff? I can't really tell what tree you're even basing this off of.
> Add idle wait support for 44x platforms
>
> This patch adds the ability for the CPU to go into wait state while in
> cpu_idle loop. This helps virtulization solutions know when the guest Linux
> kernel is in an idle state. There are two ways to do it.
This huge single line needs fixing in the next version of the patch.
>
> 1) Command line
> idle=spin <-- CPU will spin (this is the default)
> idle=wait <-- set CPU into wait state when idle
>
> 2) The device tree will be checked for the "/hypervisor" node
> If this node is seen it will use "wait" for idle, so that
> the hypervisor can know when guest Linux kernel it is in
> an idle state.
>
> This patch, unlike the last, isolates the code to 44x platforms.
In addition to the comments Tony and Hollis made, I have a few of my
own.
> Signed-off-by: Jerone Young <[EMAIL PROTECTED]>
>
> diff --git a/arch/powerpc/platforms/44x/44x.h
> b/arch/powerpc/platforms/44x/44x.h
> --- a/arch/powerpc/platforms/44x/44x.h
> +++ b/arch/powerpc/platforms/44x/44x.h
> @@ -5,4 +5,6 @@ extern void as1_writeb(u8 data, volatile
> extern void as1_writeb(u8 data, volatile u8 __iomem *addr);
> extern void ppc44x_reset_system(char *cmd);
>
> +extern int ppc44x_idle_init(void);
> +
> #endif /* __POWERPC_PLATFORMS_44X_44X_H */
The changes to this file aren't needed. See below.
> diff --git a/arch/powerpc/platforms/44x/Makefile
> b/arch/powerpc/platforms/44x/Makefile
> --- a/arch/powerpc/platforms/44x/Makefile
> +++ b/arch/powerpc/platforms/44x/Makefile
> @@ -1,4 +1,5 @@ obj-$(CONFIG_44x) := misc_44x.o
> obj-$(CONFIG_44x) := misc_44x.o
> +obj-$(CONFIG_44x) += idle.o
Just add this target to the already existing obj-(CONFIG_44x)
> obj-$(CONFIG_EBONY) += ebony.o
> obj-$(CONFIG_TAISHAN) += taishan.o
> obj-$(CONFIG_BAMBOO) += bamboo.o
> diff --git a/arch/powerpc/platforms/44x/bamboo.c
> b/arch/powerpc/platforms/44x/bamboo.c
> --- a/arch/powerpc/platforms/44x/bamboo.c
> +++ b/arch/powerpc/platforms/44x/bamboo.c
> @@ -61,3 +61,5 @@ define_machine(bamboo) {
> .restart = ppc44x_reset_system,
> .calibrate_decr = generic_calibrate_decr,
> };
> +
> +machine_late_initcall(bamboo, ppc44x_idle_init);
Ugh. Don't add an init call to every 4xx board like this. It's not
needed. See below.
> diff --git a/arch/powerpc/platforms/44x/idle.c
> b/arch/powerpc/platforms/44x/idle.c
> new file mode 100644
> --- /dev/null
> +++ b/arch/powerpc/platforms/44x/idle.c
If you're ever going to extend bare metal support for this to 40x, then
this is the wrong place for it. It should reside in
arch/powerpc/sysdev/ppc4xx_soc.c in that case.
> +
> +#include <linux/of.h>
> +#include <asm/machdep.h>
> +
> +static void ppc44x_idle(void);
This isn't needed. Move the structures below the function.
> +struct sleep_mode {
> + char *name;
> + void (*entry)(void);
> +};
> +
> +static struct sleep_mode modes[] = {
> + { .name = "spin", .entry = NULL },
> + { .name = "wait", .entry = &ppc44x_idle },
> +};
<snip>
> +int __init ppc44x_idle_init(void)
> +{
> + if(of_find_node_by_path("/hypervisor") != NULL) {
> + /* if we find /hypervisor node is in device tree,
> + set idle mode to wait */
> + current_mode = 1; /* wait mode */
> + }
> +
> + ppc_md.power_save = modes[current_mode].entry;
> + return 0;
I liked Hollis' method of assignment here.
> +}
Add an arch_initcall(ppc44x_idle_init); here and dispense with
changing every board .c file in the 44x directory.
josh
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