Patchwork [RFC,3/3] PCI/ASPM: add sysfs attribute for controlling ASPM

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Submitter Heiner Kallweit
Date April 13, 2019, 9:12 a.m.
Message ID <a0a39450-1f23-f5a0-d669-3d722e5b71dd@gmail.com>
Download mbox | patch
Permalink /patch/772353/
State New
Headers show

Comments

Heiner Kallweit - April 13, 2019, 9:12 a.m.
Background of this extension is a problem with the r8169 network driver.
Several combinations of board chipsets and network chip versions have
problems if ASPM is enabled, therefore we have to disable ASPM per
default. However especially on notebooks ASPM can provide significant
power-saving, therefore we want to give users the option to enable
ASPM. With the new sysfs attribute users can control which ASPM
link-states are disabled.

This is a first RFC version, therefore documentation of attribute is
still missing. The attribute handling was inspired by the protocol
attribute handling in drivers/media/rc/rc-main.c.
Attribute syntax in a few words:
none: allow all supported ASPM states
all: disable all ASPM states
+<state>: add state to list of disabled ASPM states
-<state>: re-enable ASPM state if supported

Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
---
 drivers/pci/pci.h       |   8 +-
 drivers/pci/pcie/aspm.c | 173 +++++++++++++++++++++++++++++++++++++++-
 2 files changed, 173 insertions(+), 8 deletions(-)

Patch

diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index d994839a3..6d4e5fc24 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -499,17 +499,13 @@  void pcie_aspm_init_link_state(struct pci_dev *pdev);
 void pcie_aspm_exit_link_state(struct pci_dev *pdev);
 void pcie_aspm_pm_state_change(struct pci_dev *pdev);
 void pcie_aspm_powersave_config_link(struct pci_dev *pdev);
+void pcie_aspm_create_sysfs_dev_files(struct pci_dev *pdev);
+void pcie_aspm_remove_sysfs_dev_files(struct pci_dev *pdev);
 #else
 static inline void pcie_aspm_init_link_state(struct pci_dev *pdev) { }
 static inline void pcie_aspm_exit_link_state(struct pci_dev *pdev) { }
 static inline void pcie_aspm_pm_state_change(struct pci_dev *pdev) { }
 static inline void pcie_aspm_powersave_config_link(struct pci_dev *pdev) { }
-#endif
-
-#ifdef CONFIG_PCIEASPM_DEBUG
-void pcie_aspm_create_sysfs_dev_files(struct pci_dev *pdev);
-void pcie_aspm_remove_sysfs_dev_files(struct pci_dev *pdev);
-#else
 static inline void pcie_aspm_create_sysfs_dev_files(struct pci_dev *pdev) { }
 static inline void pcie_aspm_remove_sysfs_dev_files(struct pci_dev *pdev) { }
 #endif
diff --git a/drivers/pci/pcie/aspm.c b/drivers/pci/pcie/aspm.c
index 7847be38e..bfbfd9134 100644
--- a/drivers/pci/pcie/aspm.c
+++ b/drivers/pci/pcie/aspm.c
@@ -42,6 +42,8 @@ 
 #define ASPM_STATE_ALL		(ASPM_STATE_L0S | ASPM_STATE_L1 |	\
 				 ASPM_STATE_L1SS)
 
+static const char power_group[] = "power";
+
 struct aspm_latency {
 	u32 l0s;			/* L0s latency (nsec) */
 	u32 l1;				/* L1 latency (nsec) */
@@ -1251,8 +1253,164 @@  static ssize_t clk_ctl_store(struct device *dev,
 
 static DEVICE_ATTR_RW(link_state);
 static DEVICE_ATTR_RW(clk_ctl);
+#endif
+
+struct aspm_sysfs_state {
+	const char *name;
+	int disable_mask;
+};
+
+static const struct aspm_sysfs_state aspm_sysfs_states[] = {
+	{ "L0S",	ASPM_STATE_L0S		},
+	{ "L1",		ASPM_STATE_L1		},
+	{ "L1.1",	ASPM_STATE_L1_1_MASK	},
+	{ "L1.2",	ASPM_STATE_L1_2_MASK	},
+};
+
+static struct pci_dev *aspm_get_parent(struct pci_dev *pdev)
+{
+	struct pci_dev *parent = pdev->bus->self;
+
+	if (pdev->has_secondary_link)
+		parent = pdev;
+
+	return parent && parent->link_state ? parent : NULL;
+}
+
+static ssize_t aspm_disable_link_state_show(struct device *dev,
+					    struct device_attribute *attr,
+					    char *buf)
+{
+	struct pci_dev *parent, *pdev = to_pci_dev(dev);
+	struct pcie_link_state *link;
+	int len = 0, i;
+
+	parent = aspm_get_parent(pdev);
+	if (!parent)
+		return -EOPNOTSUPP;
+
+	link = parent->link_state;
+
+	mutex_lock(&aspm_lock);
+
+	for (i = 0; i < ARRAY_SIZE(aspm_sysfs_states); i++) {
+		const struct aspm_sysfs_state *st = aspm_sysfs_states + i;
+
+		if (link->aspm_disable & st->disable_mask)
+			len += scnprintf(buf + len, PAGE_SIZE - len, "[%s] ",
+					 st->name);
+		else
+			len += scnprintf(buf + len, PAGE_SIZE - len, "%s ",
+					 st->name);
+	}
+
+	if (link->clkpm_disable)
+		len += scnprintf(buf + len, PAGE_SIZE - len, "[CLKPM] ");
+	else
+		len += scnprintf(buf + len, PAGE_SIZE - len, "CLKPM ");
+
+	mutex_unlock(&aspm_lock);
+
+	len += scnprintf(buf + len, PAGE_SIZE - len, "\n");
+
+	return len;
+}
+
+static ssize_t aspm_disable_link_state_store(struct device *dev,
+					     struct device_attribute *attr,
+					     const char *buf, size_t len)
+{
+	struct pci_dev *parent, *pdev = to_pci_dev(dev);
+	struct pcie_link_state *link;
+	char *buftmp = (char *)buf, *tok;
+	unsigned int disable_aspm, disable_clkpm;
+	bool first = true, add;
+	int err = 0, i;
+
+	if (aspm_disabled)
+		return -EPERM;
+
+	parent = aspm_get_parent(pdev);
+	if (!parent)
+		return -EOPNOTSUPP;
+
+	link = parent->link_state;
+
+	down_read(&pci_bus_sem);
+	mutex_lock(&aspm_lock);
+
+	disable_aspm = link->aspm_disable;
+	disable_clkpm = link->clkpm_disable;
+
+	while ((tok = strsep(&buftmp, " \n")) != NULL) {
+		bool found = false;
+
+		if (!*tok)
+			continue;
+
+		if (first) {
+			if (!strcasecmp(tok, "none")) {
+				disable_aspm = 0;
+				disable_clkpm = 0;
+				break;
+			}
+			if (!strcasecmp(tok, "all")) {
+				disable_aspm = ASPM_STATE_ALL;
+				disable_clkpm = 1;
+				break;
+			}
+			first = false;
+		}
+
+		if (*tok != '+' && *tok != '-') {
+			err = -EINVAL;
+			goto out;
+		}
+
+		add = *tok++ == '+';
+
+		for (i = 0; i < ARRAY_SIZE(aspm_sysfs_states); i++) {
+			const struct aspm_sysfs_state *st =
+						aspm_sysfs_states + i;
+
+			if (!strcasecmp(tok, st->name)) {
+				if (add)
+					disable_aspm |= st->disable_mask;
+				else
+					disable_aspm &= ~st->disable_mask;
+				found = true;
+				break;
+			}
+		}
+
+		if (!found && !strcasecmp(tok, "clkpm")) {
+			disable_clkpm = add ? 1 : 0;
+			found = true;
+		}
+
+		if (!found) {
+			err = -EINVAL;
+			goto out;
+		}
+	}
+
+	if (disable_aspm & ASPM_STATE_L1)
+		disable_aspm |= ASPM_STATE_L1SS;
+
+	link->aspm_disable = disable_aspm;
+	link->clkpm_disable = disable_clkpm;
+
+	pcie_config_aspm_link(link, policy_to_aspm_state(link));
+	pcie_set_clkpm(link, policy_to_clkpm_state(link));
+out:
+	mutex_unlock(&aspm_lock);
+	up_read(&pci_bus_sem);
+
+	return err ?: len;
+}
+
+static DEVICE_ATTR_RW(aspm_disable_link_state);
 
-static char power_group[] = "power";
 void pcie_aspm_create_sysfs_dev_files(struct pci_dev *pdev)
 {
 	struct pcie_link_state *link_state = pdev->link_state;
@@ -1260,12 +1418,18 @@  void pcie_aspm_create_sysfs_dev_files(struct pci_dev *pdev)
 	if (!link_state)
 		return;
 
+	if (link_state->aspm_support)
+		sysfs_add_file_to_group(&pdev->dev.kobj,
+			&dev_attr_aspm_disable_link_state.attr, power_group);
+
+#ifdef CONFIG_PCIEASPM_DEBUG
 	if (link_state->aspm_support)
 		sysfs_add_file_to_group(&pdev->dev.kobj,
 			&dev_attr_link_state.attr, power_group);
 	if (link_state->clkpm_capable)
 		sysfs_add_file_to_group(&pdev->dev.kobj,
 			&dev_attr_clk_ctl.attr, power_group);
+#endif
 }
 
 void pcie_aspm_remove_sysfs_dev_files(struct pci_dev *pdev)
@@ -1275,14 +1439,19 @@  void pcie_aspm_remove_sysfs_dev_files(struct pci_dev *pdev)
 	if (!link_state)
 		return;
 
+	if (link_state->aspm_support)
+		sysfs_remove_file_from_group(&pdev->dev.kobj,
+			&dev_attr_aspm_disable_link_state.attr, power_group);
+
+#ifdef CONFIG_PCIEASPM_DEBUG
 	if (link_state->aspm_support)
 		sysfs_remove_file_from_group(&pdev->dev.kobj,
 			&dev_attr_link_state.attr, power_group);
 	if (link_state->clkpm_capable)
 		sysfs_remove_file_from_group(&pdev->dev.kobj,
 			&dev_attr_clk_ctl.attr, power_group);
-}
 #endif
+}
 
 static int __init pcie_aspm_disable(char *str)
 {