FAILED: patch "[PATCH] PCI: Unify delay handling for reset and resume" failed to apply to 4.19-stable tree

The patch below does not apply to the 4.19-stable tree.
If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to <[email protected]>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-4.19.y
git checkout FETCH_HEAD
git cherry-pick -x ac91e6980563ed53afadd925fa6585ffd2bc4a2c
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<[email protected]>' --in-reply-to '[email protected]' --subject-prefix 'PATCH 4.19.y' HEAD^..

Possible dependencies:

ac91e6980563 ("PCI: Unify delay handling for reset and resume")
8ef0217227b4 ("PCI/PM: Observe reset delay irrespective of bridge_d3")
730643d33e2d ("PCI/PM: Resume subordinate bus in bus type callbacks")
18a94192e20d ("PCI/PM: Define pci_restore_standard_config() only for CONFIG_PM_SLEEP") 0c5c62ddf88c ("Merge tag 'pci-v5.16-changes' of git://git.kernel.org/pub/scm/linux/kernel/git/helgaas/pci")

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From ac91e6980563ed53afadd925fa6585ffd2bc4a2c Mon Sep 17 00:00:00 2001
From: Lukas Wunner <[email protected]>
Date: Sun, 15 Jan 2023 09:20:32 +0100
Subject: [PATCH] PCI: Unify delay handling for reset and resume

Sheng Bi reports that pci_bridge_secondary_bus_reset() may fail to wait for devices on the secondary bus to become accessible after reset:

Although it does call pci_dev_wait(), it erroneously passes the bridge's pci_dev rather than that of a child. The bridge of course is always accessible while its secondary bus is reset, so pci_dev_wait() returns immediately.

Sheng Bi proposes introducing a new pci_bridge_secondary_bus_wait() function which is called from pci_bridge_secondary_bus_reset():

https://lore.kernel.org/linux-pci/[email protected]/

However we already have pci_bridge_wait_for_secondary_bus() which does almost exactly what we need. So far it's only called on resume from D3cold (which implies a Fundamental Reset per PCIe r6.0 sec 5.8). Re-using it for Secondary Bus Resets is a leaner and more rational approach than introducing a new function.

That only requires a few minor tweaks:

- Amend pci_bridge_wait_for_secondary_bus() to await accessibility of the first device on the secondary bus by calling pci_dev_wait() after performing the prescribed delays. pci_dev_wait() needs two parameters, a reset reason and a timeout, which callers must now pass to pci_bridge_wait_for_secondary_bus(). The timeout is 1 sec for resume (PCIe r6.0 sec 6.6.1) and 60 sec for reset (commit 821cdad5c46c ("PCI:
Wait up to 60 seconds for device to become ready after FLR")). Introduce a PCI_RESET_WAIT macro for the 1 sec timeout.

- Amend pci_bridge_wait_for_secondary_bus() to return 0 on success or -ENOTTY on error for consumption by pci_bridge_secondary_bus_reset().

- Drop an unnecessary 1 sec delay from pci_reset_secondary_bus() which is now performed by pci_bridge_wait_for_secondary_bus(). A static delay this long is only necessary for Conventional PCI, so modern PCIe systems benefit from shorter reset times as a side effect.

index a2ceeacc33eb..7a19f11daca3 100644
@@ -572,7 +572,7 @@ static void pci_pm_default_resume_early(struct pci_dev *pci_dev)
 
 static void pci_pm_bridge_power_up_actions(struct pci_dev *pci_dev)
 {
-	pci_bridge_wait_for_secondary_bus(pci_dev);
+	pci_bridge_wait_for_secondary_bus(pci_dev, "resume", PCI_RESET_WAIT);
 	/*
 	 * When powering on a bridge from D3cold, the whole hierarchy may be
 	 * powered on into D0uninitialized state, resume them to give them a

index 9ed3b5550043..ce1fc3a90b3f 100644
@@ -64,6 +64,13 @@ struct pci_cap_saved_state *pci_find_saved_ext_cap(struct pci_dev *dev,
 #define PCI_PM_D3HOT_WAIT       10	/* msec */
 #define PCI_PM_D3COLD_WAIT      100	/* msec */
 
+/*
+ * Following exit from Conventional Reset, devices must be ready within 1 sec
+ * (PCIe r6.0 sec 6.6.1).  A D3cold to D0 transition implies a Conventional
+ * Reset (PCIe r6.0 sec 5.8).
+ */
+#define PCI_RESET_WAIT		1000	/* msec */
+
 void pci_update_current_state(struct pci_dev *dev, pci_power_t state);
 void pci_refresh_power_state(struct pci_dev *dev);
 int pci_power_up(struct pci_dev *dev);

@@ -86,8 +93,9 @@ void pci_msi_init(struct pci_dev *dev);
 void pci_msix_init(struct pci_dev *dev);
 bool pci_bridge_d3_possible(struct pci_dev *dev);
 void pci_bridge_d3_update(struct pci_dev *dev);
-void pci_bridge_wait_for_secondary_bus(struct pci_dev *dev);
 void pci_bridge_reconfigure_ltr(struct pci_dev *dev);
+int pci_bridge_wait_for_secondary_bus(struct pci_dev *dev, char *reset_type,
+				      int timeout);
 
 static inline void pci_wakeup_event(struct pci_dev *dev)
 {