diff options
Diffstat (limited to 'drivers/nvme/host/core.c')
| -rw-r--r-- | drivers/nvme/host/core.c | 154 |
1 files changed, 154 insertions, 0 deletions
diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c index 38efe4f752a1..849e85847ad4 100644 --- a/drivers/nvme/host/core.c +++ b/drivers/nvme/host/core.c @@ -26,6 +26,7 @@ #include <linux/ptrace.h> #include <linux/nvme_ioctl.h> #include <linux/t10-pi.h> +#include <linux/pm_qos.h> #include <scsi/sg.h> #include <asm/unaligned.h> @@ -56,6 +57,11 @@ EXPORT_SYMBOL_GPL(nvme_max_retries); static int nvme_char_major; module_param(nvme_char_major, int, 0); +static unsigned long default_ps_max_latency_us = 25000; +module_param(default_ps_max_latency_us, ulong, 0644); +MODULE_PARM_DESC(default_ps_max_latency_us, + "max power saving latency for new devices; use PM QOS to change per device"); + static LIST_HEAD(nvme_ctrl_list); static DEFINE_SPINLOCK(dev_list_lock); @@ -1252,6 +1258,122 @@ static void nvme_set_queue_limits(struct nvme_ctrl *ctrl, blk_queue_write_cache(q, vwc, vwc); } +static void nvme_configure_apst(struct nvme_ctrl *ctrl) +{ + /* + * APST (Autonomous Power State Transition) lets us program a + * table of power state transitions that the controller will + * perform automatically. We configure it with a simple + * heuristic: we are willing to spend at most 2% of the time + * transitioning between power states. Therefore, when running + * in any given state, we will enter the next lower-power + * non-operational state after waiting 100 * (enlat + exlat) + * microseconds, as long as that state's total latency is under + * the requested maximum latency. + * + * We will not autonomously enter any non-operational state for + * which the total latency exceeds ps_max_latency_us. Users + * can set ps_max_latency_us to zero to turn off APST. + */ + + unsigned apste; + struct nvme_feat_auto_pst *table; + int ret; + + /* + * If APST isn't supported or if we haven't been initialized yet, + * then don't do anything. + */ + if (!ctrl->apsta) + return; + + if (ctrl->npss > 31) { + dev_warn(ctrl->device, "NPSS is invalid; not using APST\n"); + return; + } + + table = kzalloc(sizeof(*table), GFP_KERNEL); + if (!table) + return; + + if (ctrl->ps_max_latency_us == 0) { + /* Turn off APST. */ + apste = 0; + } else { + __le64 target = cpu_to_le64(0); + int state; + + /* + * Walk through all states from lowest- to highest-power. + * According to the spec, lower-numbered states use more + * power. NPSS, despite the name, is the index of the + * lowest-power state, not the number of states. + */ + for (state = (int)ctrl->npss; state >= 0; state--) { + u64 total_latency_us, transition_ms; + + if (target) + table->entries[state] = target; + + /* + * Is this state a useful non-operational state for + * higher-power states to autonomously transition to? + */ + if (!(ctrl->psd[state].flags & + NVME_PS_FLAGS_NON_OP_STATE)) + continue; + + total_latency_us = + (u64)le32_to_cpu(ctrl->psd[state].entry_lat) + + + le32_to_cpu(ctrl->psd[state].exit_lat); + if (total_latency_us > ctrl->ps_max_latency_us) + continue; + + /* + * This state is good. Use it as the APST idle + * target for higher power states. + */ + transition_ms = total_latency_us + 19; + do_div(transition_ms, 20); + if (transition_ms > (1 << 24) - 1) + transition_ms = (1 << 24) - 1; + + target = cpu_to_le64((state << 3) | + (transition_ms << 8)); + } + + apste = 1; + } + + ret = nvme_set_features(ctrl, NVME_FEAT_AUTO_PST, apste, + table, sizeof(*table), NULL); + if (ret) + dev_err(ctrl->device, "failed to set APST feature (%d)\n", ret); + + kfree(table); +} + +static void nvme_set_latency_tolerance(struct device *dev, s32 val) +{ + struct nvme_ctrl *ctrl = dev_get_drvdata(dev); + u64 latency; + + switch (val) { + case PM_QOS_LATENCY_TOLERANCE_NO_CONSTRAINT: + case PM_QOS_LATENCY_ANY: + latency = U64_MAX; + break; + + default: + latency = val; + } + + if (ctrl->ps_max_latency_us != latency) { + ctrl->ps_max_latency_us = latency; + nvme_configure_apst(ctrl); + } +} + struct nvme_core_quirk_entry { /* * NVMe model and firmware strings are padded with spaces. For @@ -1265,6 +1387,16 @@ struct nvme_core_quirk_entry { }; static const struct nvme_core_quirk_entry core_quirks[] = { + /* + * Seen on a Samsung "SM951 NVMe SAMSUNG 256GB": using APST causes + * the controller to go out to lunch. It dies when the watchdog + * timer reads CSTS and gets 0xffffffff. + */ + { + .vid = 0x144d, + .fr = "BXW75D0Q", + .quirks = NVME_QUIRK_NO_APST, + }, }; /* match is null-terminated but idstr is space-padded. */ @@ -1307,6 +1439,7 @@ int nvme_init_identify(struct nvme_ctrl *ctrl) u64 cap; int ret, page_shift; u32 max_hw_sectors; + u8 prev_apsta; ret = ctrl->ops->reg_read32(ctrl, NVME_REG_VS, &ctrl->vs); if (ret) { @@ -1368,6 +1501,11 @@ int nvme_init_identify(struct nvme_ctrl *ctrl) ctrl->sgls = le32_to_cpu(id->sgls); ctrl->kas = le16_to_cpu(id->kas); + ctrl->npss = id->npss; + prev_apsta = ctrl->apsta; + ctrl->apsta = (ctrl->quirks & NVME_QUIRK_NO_APST) ? 0 : id->apsta; + memcpy(ctrl->psd, id->psd, sizeof(ctrl->psd)); + if (ctrl->ops->is_fabrics) { ctrl->icdoff = le16_to_cpu(id->icdoff); ctrl->ioccsz = le32_to_cpu(id->ioccsz); @@ -1392,7 +1530,15 @@ int nvme_init_identify(struct nvme_ctrl *ctrl) kfree(id); + if (ctrl->apsta && !prev_apsta) + dev_pm_qos_expose_latency_tolerance(ctrl->device); + else if (!ctrl->apsta && prev_apsta) + dev_pm_qos_hide_latency_tolerance(ctrl->device); + + nvme_configure_apst(ctrl); + ctrl->identified = true; + return ret; } EXPORT_SYMBOL_GPL(nvme_init_identify); @@ -2154,6 +2300,14 @@ int nvme_init_ctrl(struct nvme_ctrl *ctrl, struct device *dev, list_add_tail(&ctrl->node, &nvme_ctrl_list); spin_unlock(&dev_list_lock); + /* + * Initialize latency tolerance controls. The sysfs files won't + * be visible to userspace unless the device actually supports APST. + */ + ctrl->device->power.set_latency_tolerance = nvme_set_latency_tolerance; + dev_pm_qos_update_user_latency_tolerance(ctrl->device, + min(default_ps_max_latency_us, (unsigned long)S32_MAX)); + return 0; out_release_instance: nvme_release_instance(ctrl); |