Re: [PATCH v3 3/6] cpufreq: powernv: Register for OCC related opal_message notification

Preeti U Murthy
2015-05-05T03:43:14Z

On 05/04/2015 02:24 PM, Shilpasri G Bhat wrote:
> OCC is an On-Chip-Controller which takes care of power and thermal
> safety of the chip. During runtime due to power failure or
> overtemperature the OCC may throttle the frequencies of the CPUs to
> remain within the power budget.
>
> We want the cpufreq driver to be aware of such situations to be able
> to report the reason to the user. We register to opal_message_notifier
> to receive OCC messages from opal.
>
> powernv_cpufreq_throttle_check() reports any frequency throttling and
> this patch will report the reason or event that caused throttling. We
> can be throttled if OCC is reset or OCC limits Pmax due to power or
> thermal reasons. We are also notified of unthrottling after an OCC
> reset or if OCC restores Pmax on the chip.
>
> Signed-off-by: Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com>
> ---
> Changes from v2:
> - Patch split in to multiple patches.
> - This patch contains only the opal_message notification handler
>
> Changes from v1:
> - Add macros to define OCC_RESET, OCC_LOAD and OCC_THROTTLE
> - Define a structure to store chip id, chip mask which has bits set
> for cpus present in the chip, throttled state and a work_struct.
> - Modify powernv_cpufreq_throttle_check() to be called via smp_call()
> - On Pmax throttling/unthrottling update 'chip.throttled' and not the
> global 'throttled' as Pmax capping is local to the chip.
> - Remove the condition which checks if local pstate is less than Pmin
> while checking for Psafe frequency. When OCC becomes active after
> reset we update 'thottled' to false and when the cpufreq governor
> initiates a pstate change, the local pstate will be in Psafe and we
> will be reporting a false positive when we are not throttled.
> - Schedule a kworker on receiving throttling/unthrottling OCC message
> for that chip and schedule on all chips after receiving active.
> - After an OCC reset all the cpus will be in Psafe frequency. So call
> target() and restore the frequency to policy->cur after OCC_ACTIVE
> and Pmax unthrottling
> - Taken care of Viresh and Preeti's comments.
>
> drivers/cpufreq/powernv-cpufreq.c | 75 ++++++++++++++++++++++++++++++++++++++-
> 1 file changed, 74 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/cpufreq/powernv-cpufreq.c b/drivers/cpufreq/powernv-cpufreq.c
> index d0c18c9..9268424 100644
> --- a/drivers/cpufreq/powernv-cpufreq.c
> +++ b/drivers/cpufreq/powernv-cpufreq.c
> @@ -33,15 +33,19 @@
> #include <asm/firmware.h>
> #include <asm/reg.h>
> #include <asm/smp.h> /* Required for cpu_sibling_mask() in UP configs */
> +#include <asm/opal.h>
>
> #define POWERNV_MAX_PSTATES 256
> #define PMSR_PSAFE_ENABLE (1UL << 30)
> #define PMSR_SPR_EM_DISABLE (1UL << 31)
> #define PMSR_MAX(x) ((x >> 32) & 0xFF)
> #define PMSR_LP(x) ((x >> 48) & 0xFF)
> +#define OCC_RESET 0
> +#define OCC_LOAD 1
> +#define OCC_THROTTLE 2
>
> static struct cpufreq_frequency_table powernv_freqs[POWERNV_MAX_PSTATES+1];
> -static bool rebooting, throttled;
> +static bool rebooting, throttled, occ_reset;
>
> static struct chip {
> unsigned int id;
> @@ -414,6 +418,74 @@ static struct notifier_block powernv_cpufreq_reboot_nb = {
> .notifier_call = powernv_cpufreq_reboot_notifier,
> };
>
> +static char throttle_reason[][30] = {
> + "No throttling",
> + "Power Cap",
> + "Processor Over Temperature",
> + "Power Supply Failure",
> + "Over Current",
> + "OCC Reset"
> + };
> +
> +static int powernv_cpufreq_occ_msg(struct notifier_block *nb,
> + unsigned long msg_type, void *msg)
> +{
> + struct opal_msg *occ_msg = msg;
> + uint64_t token;
> + uint64_t chip_id, reason;
> +
> + if (msg_type != OPAL_MSG_OCC)
> + return 0;
> +
> + token = be64_to_cpu(occ_msg->params[0]);
> +
> + switch (token) {
> + case OCC_RESET:
> + occ_reset = true;
> + /*
> + * powernv_cpufreq_throttle_check() is called in
> + * target() callback which can detect the throttle state
> + * for governors like ondemand.
> + * But static governors will not call target() often thus
> + * report throttling here.
> + */
> + if (!throttled) {
> + throttled = true;
> + pr_crit("CPU Frequency is throttled\n");
> + }
> + pr_info("OCC: Reset\n");
> + break;
> + case OCC_LOAD:
> + pr_info("OCC: Loaded\n");
> + break;
> + case OCC_THROTTLE:
> + chip_id = be64_to_cpu(occ_msg->params[1]);
> + reason = be64_to_cpu(occ_msg->params[2]);
> +
> + if (occ_reset) {
> + occ_reset = false;
> + throttled = false;
> + pr_info("OCC: Active\n");
> + return 0;
> + }
> +
> + if (reason && reason <= 5)
> + pr_info("OCC: Chip %u Pmax reduced due to %s\n",
> + (unsigned int)chip_id,
> + throttle_reason[reason]);
> + else if (!reason)
> + pr_info("OCC: Chip %u %s\n", (unsigned int)chip_id,
> + throttle_reason[reason]);
> + }
> + return 0;
> +}
> +
> +static struct notifier_block powernv_cpufreq_opal_nb = {
> + .notifier_call = powernv_cpufreq_occ_msg,
> + .next = NULL,
> + .priority = 0,
> +};
> +
> static void powernv_cpufreq_stop_cpu(struct cpufreq_policy *policy)
> {
> struct powernv_smp_call_data freq_data;
> @@ -481,6 +553,7 @@ static int __init powernv_cpufreq_init(void)
> return rc;
>
> register_reboot_notifier(&powernv_cpufreq_reboot_nb);
> + opal_message_notifier_register(OPAL_MSG_OCC, &powernv_cpufreq_opal_nb);
> return cpufreq_register_driver(&powernv_cpufreq_driver);
> }
> module_init(powernv_cpufreq_init);
>

Looks good.

Reviewed-by: Preeti U Murthy <preeti@linux.vnet.ibm.com>