Re: [RFC PATCH v2 1/3] cpuidle/powernv: Add support for states with ibm,cpuidle-state-v1

[Frank Rowand]

+ devicetree mail list

On 10/11/18 06:22, Akshay Adiga wrote:
> This patch adds support for new device-tree format for idle state
> description.
> 
> Previously if a older kernel runs on a newer firmware, it may enable
> all available states irrespective of its capability of handling it.
> New device tree format adds a compatible flag, so that only kernel
> which has the capability to handle the version of stop state will enable
> it.
> 
> Older kernel will still see stop0 and stop0_lite in older format and we
> will depricate it after some time.
> 
> 1) Idea is to bump up the version in firmware if we find a bug or
> regression in stop states. A fix will be provided in linux which would
> now know about the bumped up version of stop states, where as kernel
> without fixes would ignore the states.
> 
> 2) Slowly deprecate cpuidle /cpuhotplug threshold which is hard-coded
> into cpuidle-powernv driver. Instead use compatible strings to indicate
> if idle state is suitable for cpuidle and hotplug.
> 
> New idle state device tree format :
>power-mgt {
> ...
>  ibm,enabled-stop-levels = <0xec00>;
>  ibm,cpu-idle-state-psscr-mask = <0x0 0x3003ff 0x0 0x3003ff>;
>  ibm,cpu-idle-state-latencies-ns = <0x3e8 0x7d0>;
>  ibm,cpu-idle-state-psscr = <0x0 0x330 0x0 0x300330>;
>  ibm,cpu-idle-state-flags = <0x10 0x101000>;
>  ibm,cpu-idle-state-residency-ns = <0x2710 0x4e20>;
>  ibm,idle-states {
>  stop4 {
>  flags = <0x207000>;
>  compatible = "ibm,state-v1",
>   "opal-supported";
>  type = "cpuidle";
>  psscr-mask = <0x0 0x3003ff>;
>  handle = <0x102>;
>  latency-ns = <0x186a0>;
>  residency-ns = <0x989680>;
>  psscr = <0x0 0x300374>;
>   };
> ...
> stop11 {
>  ...
>  compatible = "ibm,state-v1",
>   "opal-supported";
>  type = "cpuoffline";
>  ...
>   };
>  };
> type strings :
> "cpuidle" : indicates it should be used by cpuidle-driver
> "cpuoffline" : indicates it should be used by hotplug driver
> 
> compatible strings :
> "ibm,state-v1" : kernel checks if it knows about this version
> "opal-supported" : indicates kernel can fall back to use opal
>  for stop-transitions
> 
> Signed-off-by: Akshay Adiga 
> ---
> 
> Changes from v1 :
>  - Code is rebased on Nick Piggin's v4 patch "powerpc/64s: reimplement book3s
>idle code in C"
>  - Moved "cpuidle" and "cpuoffline" as seperate property called
>"type"
>  
> 
>  arch/powerpc/include/asm/cpuidle.h|   9 ++
>  arch/powerpc/platforms/powernv/idle.c | 132 +-
>  drivers/cpuidle/cpuidle-powernv.c |  31 --
>  3 files changed, 160 insertions(+), 12 deletions(-)
> 
> diff --git a/arch/powerpc/include/asm/cpuidle.h 
> b/arch/powerpc/include/asm/cpuidle.h
> index 9844b3ded187..e920a15e797f 100644
> --- a/arch/powerpc/include/asm/cpuidle.h
> +++ b/arch/powerpc/include/asm/cpuidle.h
> @@ -70,14 +70,23 @@
>  
>  #ifndef __ASSEMBLY__
>  
> +enum idle_state_type_t {
> + CPUIDLE_TYPE,
> + CPUOFFLINE_TYPE
> +};
> +
> +#define POWERNV_THRESHOLD_LATENCY_NS 20
> +#define PNV_VER_NAME_LEN32
>  #define PNV_IDLE_NAME_LEN16
>  struct pnv_idle_states_t {
>   char name[PNV_IDLE_NAME_LEN];
> + char version[PNV_VER_NAME_LEN];
>   u32 latency_ns;
>   u32 residency_ns;
>   u64 psscr_val;
>   u64 psscr_mask;
>   u32 flags;
> + enum idle_state_type_t type;
>   bool valid;
>  };
>  
> diff --git a/arch/powerpc/platforms/powernv/idle.c 
> b/arch/powerpc/platforms/powernv/idle.c
> index 96186af9e953..755918402591 100644
> --- a/arch/powerpc/platforms/powernv/idle.c
> +++ b/arch/powerpc/platforms/powernv/idle.c
> @@ -54,6 +54,20 @@ static bool default_stop_found;
>  static u64 pnv_first_tb_loss_level = MAX_STOP_STATE + 1;
>  static u64 pnv_first_hv_loss_level = MAX_STOP_STATE + 1;
>  
> +
> +static int parse_dt_v1(struct device_node *np);
> +struct stop_version_t {
> + const char name[PNV_VER_NAME_LEN];
> + int (*parser_fn)(struct device_node *np);
> +};
> +struct stop_version_t known_versions[] = {
> + {
> + .name =  "ibm,state-v1",
> + .parser_fn = parse_dt_v1,
> + }
> + };
> +const int nr_known_versions = 1;
> +
>  /*
>   * psscr value and mask of the deepest stop idle state.
>   * Used when a cpu is offlined.
> @@ -1195,6 +1209,77 @@ static void __init pnv_probe_idle_states(void)
>   supported_cpuidle_states |= pnv_idle_states[i].flags;
>  }
>  
> +static int 

[RFC PATCH v2 1/3] cpuidle/powernv: Add support for states with ibm, cpuidle-state-v1

[Akshay Adiga]

This patch adds support for new device-tree format for idle state
description.

Previously if a older kernel runs on a newer firmware, it may enable
all available states irrespective of its capability of handling it.
New device tree format adds a compatible flag, so that only kernel
which has the capability to handle the version of stop state will enable
it.

Older kernel will still see stop0 and stop0_lite in older format and we
will depricate it after some time.

1) Idea is to bump up the version in firmware if we find a bug or
regression in stop states. A fix will be provided in linux which would
now know about the bumped up version of stop states, where as kernel
without fixes would ignore the states.

2) Slowly deprecate cpuidle /cpuhotplug threshold which is hard-coded
into cpuidle-powernv driver. Instead use compatible strings to indicate
if idle state is suitable for cpuidle and hotplug.

New idle state device tree format :
   power-mgt {
...
 ibm,enabled-stop-levels = <0xec00>;
 ibm,cpu-idle-state-psscr-mask = <0x0 0x3003ff 0x0 0x3003ff>;
 ibm,cpu-idle-state-latencies-ns = <0x3e8 0x7d0>;
 ibm,cpu-idle-state-psscr = <0x0 0x330 0x0 0x300330>;
 ibm,cpu-idle-state-flags = <0x10 0x101000>;
 ibm,cpu-idle-state-residency-ns = <0x2710 0x4e20>;
 ibm,idle-states {
 stop4 {
 flags = <0x207000>;
 compatible = "ibm,state-v1",
  "opal-supported";
 type = "cpuidle";
 psscr-mask = <0x0 0x3003ff>;
 handle = <0x102>;
 latency-ns = <0x186a0>;
 residency-ns = <0x989680>;
 psscr = <0x0 0x300374>;
  };
...
stop11 {
 ...
 compatible = "ibm,state-v1",
  "opal-supported";
 type = "cpuoffline";
 ...
  };
 };
type strings :
"cpuidle" : indicates it should be used by cpuidle-driver
"cpuoffline" : indicates it should be used by hotplug driver

compatible strings :
"ibm,state-v1" : kernel checks if it knows about this version
"opal-supported" : indicates kernel can fall back to use opal
   for stop-transitions

Signed-off-by: Akshay Adiga 
---

Changes from v1 :
 - Code is rebased on Nick Piggin's v4 patch "powerpc/64s: reimplement book3s
   idle code in C"
 - Moved "cpuidle" and "cpuoffline" as seperate property called
   "type"
 

 arch/powerpc/include/asm/cpuidle.h|   9 ++
 arch/powerpc/platforms/powernv/idle.c | 132 +-
 drivers/cpuidle/cpuidle-powernv.c |  31 --
 3 files changed, 160 insertions(+), 12 deletions(-)

diff --git a/arch/powerpc/include/asm/cpuidle.h 
b/arch/powerpc/include/asm/cpuidle.h
index 9844b3ded187..e920a15e797f 100644
--- a/arch/powerpc/include/asm/cpuidle.h
+++ b/arch/powerpc/include/asm/cpuidle.h
@@ -70,14 +70,23 @@
 
 #ifndef __ASSEMBLY__
 
+enum idle_state_type_t {
+   CPUIDLE_TYPE,
+   CPUOFFLINE_TYPE
+};
+
+#define POWERNV_THRESHOLD_LATENCY_NS 20
+#define PNV_VER_NAME_LEN32
 #define PNV_IDLE_NAME_LEN16
 struct pnv_idle_states_t {
char name[PNV_IDLE_NAME_LEN];
+   char version[PNV_VER_NAME_LEN];
u32 latency_ns;
u32 residency_ns;
u64 psscr_val;
u64 psscr_mask;
u32 flags;
+   enum idle_state_type_t type;
bool valid;
 };
 
diff --git a/arch/powerpc/platforms/powernv/idle.c 
b/arch/powerpc/platforms/powernv/idle.c
index 96186af9e953..755918402591 100644
--- a/arch/powerpc/platforms/powernv/idle.c
+++ b/arch/powerpc/platforms/powernv/idle.c
@@ -54,6 +54,20 @@ static bool default_stop_found;
 static u64 pnv_first_tb_loss_level = MAX_STOP_STATE + 1;
 static u64 pnv_first_hv_loss_level = MAX_STOP_STATE + 1;
 
+
+static int parse_dt_v1(struct device_node *np);
+struct stop_version_t {
+   const char name[PNV_VER_NAME_LEN];
+   int (*parser_fn)(struct device_node *np);
+};
+struct stop_version_t known_versions[] = {
+   {
+   .name =  "ibm,state-v1",
+   .parser_fn = parse_dt_v1,
+   }
+   };
+const int nr_known_versions = 1;
+
 /*
  * psscr value and mask of the deepest stop idle state.
  * Used when a cpu is offlined.
@@ -1195,6 +1209,77 @@ static void __init pnv_probe_idle_states(void)
supported_cpuidle_states |= pnv_idle_states[i].flags;
 }
 
+static int parse_dt_v1(struct device_node *dt_node)
+{
+   const char *temp_str;
+   int rc;
+   int i = nr_pnv_idle_states;
+
+   if (!dt_node) {
+   pr_err("Invalid device_node\n");
+   return -EINVAL;
+   }
+
+   rc = of_property_read_string(dt_node, "name",