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Message-Id: <20250422115548.1483-1-ilpo.jarvinen@linux.intel.com>
Date: Tue, 22 Apr 2025 14:55:47 +0300
From: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To: Lukas Wunner <lukas@...ner.de>,
Bjorn Helgaas <bhelgaas@...gle.com>,
Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>,
linux-pci@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: [PATCH v2 1/1] PCI/bwctrl: Replace lbms_count with PCI_LINK_LBMS_SEEN flag
PCIe BW controller counts LBMS assertions for the purposes of the
Target Speed quirk. It was also a plan to expose the LBMS count through
sysfs to allow better diagnosing link related issues. Lukas Wunner
suggested, however, that adding a trace event would be better for
diagnostics purposes. Leaving only Target Speed quirk as an user of the
lbms_count.
The logic in the Target Speed quirk does not require keeping count of
LBMS assertions but a simple flag is enough which can be placed into
pci_dev's priv_flags. The reduced complexity allows removing
pcie_bwctrl_lbms_rwsem.
As bwctrl is not yet probed when the Target Speed quirk runs during
boot, the LBMS in Link Status register has to still be checked by
the quirk.
The priv_flags numbering is not continuous because hotplug code added
a few flags to fill numbers 4-5 (hotplug and bwctrl changes are routed
through in different branches).
Suggested-by: Lukas Wunner <lukas@...ner.de>
Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
---
This will conflict with the new flags Lukas added due to the hp fixes
but it should be simple to deal with that conflict while merging the
topic branches.
v2:
- Change flag value to 6 to make merging with the newly added HP flags easier
- Renamed flag to PCI_LINK_LBMS_SEEN to match the naming of the new HP flags
drivers/pci/hotplug/pciehp_ctrl.c | 2 +-
drivers/pci/pci.c | 2 +-
drivers/pci/pci.h | 10 ++---
drivers/pci/pcie/bwctrl.c | 63 +++++++++----------------------
drivers/pci/quirks.c | 10 ++---
5 files changed, 25 insertions(+), 62 deletions(-)
diff --git a/drivers/pci/hotplug/pciehp_ctrl.c b/drivers/pci/hotplug/pciehp_ctrl.c
index d603a7aa7483..bcc938d4420f 100644
--- a/drivers/pci/hotplug/pciehp_ctrl.c
+++ b/drivers/pci/hotplug/pciehp_ctrl.c
@@ -131,7 +131,7 @@ static void remove_board(struct controller *ctrl, bool safe_removal)
INDICATOR_NOOP);
/* Don't carry LBMS indications across */
- pcie_reset_lbms_count(ctrl->pcie->port);
+ pcie_reset_lbms(ctrl->pcie->port);
}
static int pciehp_enable_slot(struct controller *ctrl);
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 4d7c9f64ea24..3d94cf33c1b6 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -4757,7 +4757,7 @@ int pcie_retrain_link(struct pci_dev *pdev, bool use_lt)
* to track link speed or width changes made by hardware itself
* in attempt to correct unreliable link operation.
*/
- pcie_reset_lbms_count(pdev);
+ pcie_reset_lbms(pdev);
return rc;
}
diff --git a/drivers/pci/pci.h b/drivers/pci/pci.h
index b81e99cd4b62..887811fbe722 100644
--- a/drivers/pci/pci.h
+++ b/drivers/pci/pci.h
@@ -557,6 +557,7 @@ static inline int pci_dev_set_disconnected(struct pci_dev *dev, void *unused)
#define PCI_DPC_RECOVERED 1
#define PCI_DPC_RECOVERING 2
#define PCI_DEV_REMOVED 3
+#define PCI_LINK_LBMS_SEEN 6
static inline void pci_dev_assign_added(struct pci_dev *dev)
{
@@ -824,14 +825,9 @@ static inline void pcie_ecrc_get_policy(char *str) { }
#endif
#ifdef CONFIG_PCIEPORTBUS
-void pcie_reset_lbms_count(struct pci_dev *port);
-int pcie_lbms_count(struct pci_dev *port, unsigned long *val);
+void pcie_reset_lbms(struct pci_dev *port);
#else
-static inline void pcie_reset_lbms_count(struct pci_dev *port) {}
-static inline int pcie_lbms_count(struct pci_dev *port, unsigned long *val)
-{
- return -EOPNOTSUPP;
-}
+static inline void pcie_reset_lbms(struct pci_dev *port) {}
#endif
struct pci_dev_reset_methods {
diff --git a/drivers/pci/pcie/bwctrl.c b/drivers/pci/pcie/bwctrl.c
index d8d2aa85a229..ab0387ff2de2 100644
--- a/drivers/pci/pcie/bwctrl.c
+++ b/drivers/pci/pcie/bwctrl.c
@@ -38,12 +38,10 @@
/**
* struct pcie_bwctrl_data - PCIe bandwidth controller
* @set_speed_mutex: Serializes link speed changes
- * @lbms_count: Count for LBMS (since last reset)
* @cdev: Thermal cooling device associated with the port
*/
struct pcie_bwctrl_data {
struct mutex set_speed_mutex;
- atomic_t lbms_count;
struct thermal_cooling_device *cdev;
};
@@ -202,15 +200,14 @@ int pcie_set_target_speed(struct pci_dev *port, enum pci_bus_speed speed_req,
static void pcie_bwnotif_enable(struct pcie_device *srv)
{
- struct pcie_bwctrl_data *data = srv->port->link_bwctrl;
struct pci_dev *port = srv->port;
u16 link_status;
int ret;
- /* Count LBMS seen so far as one */
+ /* Note down if LBMS has been seen so far */
ret = pcie_capability_read_word(port, PCI_EXP_LNKSTA, &link_status);
if (ret == PCIBIOS_SUCCESSFUL && link_status & PCI_EXP_LNKSTA_LBMS)
- atomic_inc(&data->lbms_count);
+ set_bit(PCI_LINK_LBMS_SEEN, &port->priv_flags);
pcie_capability_set_word(port, PCI_EXP_LNKCTL,
PCI_EXP_LNKCTL_LBMIE | PCI_EXP_LNKCTL_LABIE);
@@ -233,7 +230,6 @@ static void pcie_bwnotif_disable(struct pci_dev *port)
static irqreturn_t pcie_bwnotif_irq(int irq, void *context)
{
struct pcie_device *srv = context;
- struct pcie_bwctrl_data *data = srv->port->link_bwctrl;
struct pci_dev *port = srv->port;
u16 link_status, events;
int ret;
@@ -247,7 +243,7 @@ static irqreturn_t pcie_bwnotif_irq(int irq, void *context)
return IRQ_NONE;
if (events & PCI_EXP_LNKSTA_LBMS)
- atomic_inc(&data->lbms_count);
+ set_bit(PCI_LINK_LBMS_SEEN, &port->priv_flags);
pcie_capability_write_word(port, PCI_EXP_LNKSTA, events);
@@ -262,31 +258,10 @@ static irqreturn_t pcie_bwnotif_irq(int irq, void *context)
return IRQ_HANDLED;
}
-void pcie_reset_lbms_count(struct pci_dev *port)
+void pcie_reset_lbms(struct pci_dev *port)
{
- struct pcie_bwctrl_data *data;
-
- guard(rwsem_read)(&pcie_bwctrl_lbms_rwsem);
- data = port->link_bwctrl;
- if (data)
- atomic_set(&data->lbms_count, 0);
- else
- pcie_capability_write_word(port, PCI_EXP_LNKSTA,
- PCI_EXP_LNKSTA_LBMS);
-}
-
-int pcie_lbms_count(struct pci_dev *port, unsigned long *val)
-{
- struct pcie_bwctrl_data *data;
-
- guard(rwsem_read)(&pcie_bwctrl_lbms_rwsem);
- data = port->link_bwctrl;
- if (!data)
- return -ENOTTY;
-
- *val = atomic_read(&data->lbms_count);
-
- return 0;
+ clear_bit(PCI_LINK_LBMS_SEEN, &port->priv_flags);
+ pcie_capability_write_word(port, PCI_EXP_LNKSTA, PCI_EXP_LNKSTA_LBMS);
}
static int pcie_bwnotif_probe(struct pcie_device *srv)
@@ -308,18 +283,16 @@ static int pcie_bwnotif_probe(struct pcie_device *srv)
return ret;
scoped_guard(rwsem_write, &pcie_bwctrl_setspeed_rwsem) {
- scoped_guard(rwsem_write, &pcie_bwctrl_lbms_rwsem) {
- port->link_bwctrl = data;
+ port->link_bwctrl = data;
- ret = request_irq(srv->irq, pcie_bwnotif_irq,
- IRQF_SHARED, "PCIe bwctrl", srv);
- if (ret) {
- port->link_bwctrl = NULL;
- return ret;
- }
-
- pcie_bwnotif_enable(srv);
+ ret = request_irq(srv->irq, pcie_bwnotif_irq,
+ IRQF_SHARED, "PCIe bwctrl", srv);
+ if (ret) {
+ port->link_bwctrl = NULL;
+ return ret;
}
+
+ pcie_bwnotif_enable(srv);
}
pci_dbg(port, "enabled with IRQ %d\n", srv->irq);
@@ -339,13 +312,11 @@ static void pcie_bwnotif_remove(struct pcie_device *srv)
pcie_cooling_device_unregister(data->cdev);
scoped_guard(rwsem_write, &pcie_bwctrl_setspeed_rwsem) {
- scoped_guard(rwsem_write, &pcie_bwctrl_lbms_rwsem) {
- pcie_bwnotif_disable(srv->port);
+ pcie_bwnotif_disable(srv->port);
- free_irq(srv->irq, srv);
+ free_irq(srv->irq, srv);
- srv->port->link_bwctrl = NULL;
- }
+ srv->port->link_bwctrl = NULL;
}
}
diff --git a/drivers/pci/quirks.c b/drivers/pci/quirks.c
index 8d610c17e0f2..64ac1ee944d3 100644
--- a/drivers/pci/quirks.c
+++ b/drivers/pci/quirks.c
@@ -38,14 +38,10 @@
static bool pcie_lbms_seen(struct pci_dev *dev, u16 lnksta)
{
- unsigned long count;
- int ret;
-
- ret = pcie_lbms_count(dev, &count);
- if (ret < 0)
- return lnksta & PCI_EXP_LNKSTA_LBMS;
+ if (test_bit(PCI_LINK_LBMS_SEEN, &dev->priv_flags))
+ return true;
- return count > 0;
+ return lnksta & PCI_EXP_LNKSTA_LBMS;
}
/*
base-commit: 0af2f6be1b4281385b618cb86ad946eded089ac8
--
2.39.5
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