Merge branch 'pci/reset'

- Always observe reset delay when waking devices from D3cold, e.g., after
  system sleep, regardless of whether we're allowed to runtime-suspend to
  D3cold (Lukas Wunner)

- Unify reset and resume delays to wait for downstream devices after a
  bridge reset (Lukas Wunner)

- Wait for downstream devices after a DPC-induced bridge reset (Lukas
  Wunner)

* pci/reset:
  PCI/DPC: Await readiness of secondary bus after reset
  PCI: Unify delay handling for reset and resume
  PCI/PM: Observe reset delay irrespective of bridge_d3

1 files changed, 25 insertions, 34 deletions

diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 9d98bba72af9..5bf611e17281 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -167,9 +167,6 @@ static int __init pcie_port_pm_setup(char *str)
 }
 __setup("pcie_port_pm=", pcie_port_pm_setup);
 
-/* Time to wait after a reset for device to become responsive */
-#define PCIE_RESET_READY_POLL_MS 60000
-
 /**
  * pci_bus_max_busnr - returns maximum PCI bus number of given bus' children
  * @bus: pointer to PCI bus structure to search
@@ -1174,7 +1171,7 @@ static int pci_dev_wait(struct pci_dev *dev, char *reset_type, int timeout)
 			return -ENOTTY;
 		}
 
-		if (delay > 1000)
+		if (delay > PCI_RESET_WAIT)
 			pci_info(dev, "not ready %dms after %s; waiting\n",
 				 delay - 1, reset_type);
 
@@ -1183,7 +1180,7 @@ static int pci_dev_wait(struct pci_dev *dev, char *reset_type, int timeout)
 		pci_read_config_dword(dev, PCI_COMMAND, &id);
 	}
 
-	if (delay > 1000)
+	if (delay > PCI_RESET_WAIT)
 		pci_info(dev, "ready %dms after %s\n", delay - 1,
 			 reset_type);
 
@@ -4948,24 +4945,31 @@ static int pci_bus_max_d3cold_delay(const struct pci_bus *bus)
 /**
  * pci_bridge_wait_for_secondary_bus - Wait for secondary bus to be accessible
  * @dev: PCI bridge
+ * @reset_type: reset type in human-readable form
+ * @timeout: maximum time to wait for devices on secondary bus (milliseconds)
  *
  * Handle necessary delays before access to the devices on the secondary
- * side of the bridge are permitted after D3cold to D0 transition.
+ * side of the bridge are permitted after D3cold to D0 transition
+ * or Conventional Reset.
  *
  * For PCIe this means the delays in PCIe 5.0 section 6.6.1. For
  * conventional PCI it means Tpvrh + Trhfa specified in PCI 3.0 section
  * 4.3.2.
+ *
+ * Return 0 on success or -ENOTTY if the first device on the secondary bus
+ * failed to become accessible.
  */
-void pci_bridge_wait_for_secondary_bus(struct pci_dev *dev)
+int pci_bridge_wait_for_secondary_bus(struct pci_dev *dev, char *reset_type,
+				      int timeout)
 {
 	struct pci_dev *child;
 	int delay;
 
 	if (pci_dev_is_disconnected(dev))
-		return;
+		return 0;
 
-	if (!pci_is_bridge(dev) || !dev->bridge_d3)
-		return;
+	if (!pci_is_bridge(dev))
+		return 0;
 
 	down_read(&pci_bus_sem);
 
@@ -4977,14 +4981,14 @@ void pci_bridge_wait_for_secondary_bus(struct pci_dev *dev)
 	 */
 	if (!dev->subordinate || list_empty(&dev->subordinate->devices)) {
 		up_read(&pci_bus_sem);
-		return;
+		return 0;
 	}
 
 	/* Take d3cold_delay requirements into account */
 	delay = pci_bus_max_d3cold_delay(dev->subordinate);
 	if (!delay) {
 		up_read(&pci_bus_sem);
-		return;
+		return 0;
 	}
 
 	child = list_first_entry(&dev->subordinate->devices, struct pci_dev,
@@ -4993,14 +4997,12 @@ void pci_bridge_wait_for_secondary_bus(struct pci_dev *dev)
 
 	/*
 	 * Conventional PCI and PCI-X we need to wait Tpvrh + Trhfa before
-	 * accessing the device after reset (that is 1000 ms + 100 ms). In
-	 * practice this should not be needed because we don't do power
-	 * management for them (see pci_bridge_d3_possible()).
+	 * accessing the device after reset (that is 1000 ms + 100 ms).
 	 */
 	if (!pci_is_pcie(dev)) {
 		pci_dbg(dev, "waiting %d ms for secondary bus\n", 1000 + delay);
 		msleep(1000 + delay);
-		return;
+		return 0;
 	}
 
 	/*
@@ -5017,11 +5019,11 @@ void pci_bridge_wait_for_secondary_bus(struct pci_dev *dev)
 	 * configuration requests if we only wait for 100 ms (see
 	 * https://bugzilla.kernel.org/show_bug.cgi?id=203885).
 	 *
-	 * Therefore we wait for 100 ms and check for the device presence.
-	 * If it is still not present give it an additional 100 ms.
+	 * Therefore we wait for 100 ms and check for the device presence
+	 * until the timeout expires.
 	 */
 	if (!pcie_downstream_port(dev))
-		return;
+		return 0;
 
 	if (pcie_get_speed_cap(dev) <= PCIE_SPEED_5_0GT) {
 		pci_dbg(dev, "waiting %d ms for downstream link\n", delay);
@@ -5032,14 +5034,11 @@ void pci_bridge_wait_for_secondary_bus(struct pci_dev *dev)
 		if (!pcie_wait_for_link_delay(dev, true, delay)) {
 			/* Did not train, no need to wait any further */
 			pci_info(dev, "Data Link Layer Link Active not set in 1000 msec\n");
-			return;
+			return -ENOTTY;
 		}
 	}
 
-	if (!pci_device_is_present(child)) {
-		pci_dbg(child, "waiting additional %d ms to become accessible\n", delay);
-		msleep(delay);
-	}
+	return pci_dev_wait(child, reset_type, timeout - delay);
 }
 
 void pci_reset_secondary_bus(struct pci_dev *dev)
@@ -5058,15 +5057,6 @@ void pci_reset_secondary_bus(struct pci_dev *dev)
 
 	ctrl &= ~PCI_BRIDGE_CTL_BUS_RESET;
 	pci_write_config_word(dev, PCI_BRIDGE_CONTROL, ctrl);
-
-	/*
-	 * Trhfa for conventional PCI is 2^25 clock cycles.
-	 * Assuming a minimum 33MHz clock this results in a 1s
-	 * delay before we can consider subordinate devices to
-	 * be re-initialized.  PCIe has some ways to shorten this,
-	 * but we don't make use of them yet.
-	 */
-	ssleep(1);
 }
 
 void __weak pcibios_reset_secondary_bus(struct pci_dev *dev)
@@ -5085,7 +5075,8 @@ int pci_bridge_secondary_bus_reset(struct pci_dev *dev)
 {
 	pcibios_reset_secondary_bus(dev);
 
-	return pci_dev_wait(dev, "bus reset", PCIE_RESET_READY_POLL_MS);
+	return pci_bridge_wait_for_secondary_bus(dev, "bus reset",
+						 PCIE_RESET_READY_POLL_MS);
 }
 EXPORT_SYMBOL_GPL(pci_bridge_secondary_bus_reset);