From: Ilpo Järvinen Date: Tue, 22 Apr 2025 11:55:47 +0000 (+0300) Subject: PCI/bwctrl: Replace lbms_count with PCI_LINK_LBMS_SEEN flag X-Git-Tag: v6.16-rc1~50^2~25^2~1 X-Git-Url: http://git.ipfire.org/?a=commitdiff_plain;h=2389d8dc38fee18176c49e9c4804f5ecc55807fa;p=thirdparty%2Fkernel%2Flinux.git PCI/bwctrl: Replace lbms_count with PCI_LINK_LBMS_SEEN flag PCIe BW controller counted LBMS assertions for the purposes of the Target Speed quirk (pcie_failed_link_retrain()). 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 pcie_failed_link_retrain() as a user of the lbms_count. The logic in pcie_failed_link_retrain() does not require keeping count of LBMS assertions, so replace lbms_count with a simple flag in pci_dev's priv_flags. The reduced complexity allows removing pcie_bwctrl_lbms_rwsem. Since pcie_failed_link_retrain() runs before bwctrl is probed during boot, the LBMS in Link Status register still has to 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 Signed-off-by: Ilpo Järvinen [bhelgaas: commit log] Signed-off-by: Bjorn Helgaas [kwilczynski: squashed a fix to resolve build failures from https://lore.kernel.org/all/20250508090036.1528-1-ilpo.jarvinen@linux.intel.com] Signed-off-by: Krzysztof Wilczyński Reviewed-by: Lukas Wunner Link: https://patch.msgid.link/20250422115548.1483-1-ilpo.jarvinen@linux.intel.com --- diff --git a/drivers/pci/hotplug/pciehp_ctrl.c b/drivers/pci/hotplug/pciehp_ctrl.c index d603a7aa74838..bcc938d4420f3 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 4d7c9f64ea24e..3d94cf33c1b63 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 b81e99cd4b62a..887811fbe7221 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 d8d2aa85a2292..f31fbbd514900 100644 --- a/drivers/pci/pcie/bwctrl.c +++ b/drivers/pci/pcie/bwctrl.c @@ -38,24 +38,14 @@ /** * 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; }; -/* - * Prevent port removal during LBMS count accessors and Link Speed changes. - * - * These have to be differentiated because pcie_bwctrl_change_speed() calls - * pcie_retrain_link() which uses LBMS count reset accessor on success - * (using just one rwsem triggers "possible recursive locking detected" - * warning). - */ -static DECLARE_RWSEM(pcie_bwctrl_lbms_rwsem); +/* Prevent port removal during Link Speed changes. */ static DECLARE_RWSEM(pcie_bwctrl_setspeed_rwsem); static bool pcie_valid_speed(enum pci_bus_speed speed) @@ -202,15 +192,14 @@ 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 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 +222,6 @@ 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 +235,7 @@ 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 +250,10 @@ static irqreturn_t pcie_bwnotif_irq(int irq, void *context) return IRQ_HANDLED; } -void pcie_reset_lbms_count(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) +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) - 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 +275,16 @@ 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; - - ret = request_irq(srv->irq, pcie_bwnotif_irq, - IRQF_SHARED, "PCIe bwctrl", srv); - if (ret) { - port->link_bwctrl = NULL; - return ret; - } + port->link_bwctrl = data; - 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 +304,11 @@ 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 8d610c17e0f2f..64ac1ee944d3a 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; } /*