Commit 0b6f6593 authored Jan 09, 2025 by Maciej S. Szmigiero Committed by Jakub Kicinski Jan 15, 2025

net: wwan: iosm: Fix hibernation by re-binding the driver around it

Currently, the driver is seriously broken with respect to the
hibernation (S4): after image restore the device is back into
IPC_MEM_EXEC_STAGE_BOOT (which AFAIK means bootloader stage) and needs
full re-launch of the rest of its firmware, but the driver restore
handler treats the device as merely sleeping and just sends it a
wake-up command.

This wake-up command times out but device nodes (/dev/wwan*) remain
accessible.
However attempting to use them causes the bootloader to crash and
enter IPC_MEM_EXEC_STAGE_CD_READY stage (which apparently means "a crash
dump is ready").

It seems that the device cannot be re-initialized from this crashed
stage without toggling some reset pin (on my test platform that's
apparently what the device _RST ACPI method does).

While it would theoretically be possible to rewrite the driver to tear
down the whole MUX / IPC layers on hibernation (so the bootloader does
not crash from improper access) and then re-launch the device on
restore this would require significant refactoring of the driver
(believe me, I've tried), since there are quite a few assumptions
hard-coded in the driver about the device never being partially
de-initialized (like channels other than devlink cannot be closed,
for example).
Probably this would also need some programming guide for this hardware.

Considering that the driver seems orphaned [1] and other people are
hitting this issue too [2] fix it by simply unbinding the PCI driver
before hibernation and re-binding it after restore, much like
USB_QUIRK_RESET_RESUME does for USB devices that exhibit a similar
problem.

Tested on XMM7360 in HP EliteBook 855 G7 both with s2idle (which uses
the existing suspend / resume handlers) and S4 (which uses the new code).

[1]: https://lore.kernel.org/all/c248f0b4-2114-4c61-905f-466a786bdebb@leemhuis.info/
[2]:
https://github.com/xmm7360/xmm7360-pci/issues/211#issuecomment-1804139413



Reviewed-by: Sergey Ryazanov <ryazanov.s.a@gmail.com>
Signed-off-by: Maciej S. Szmigiero <mail@maciej.szmigiero.name>
Link: https://patch.msgid.link/e60287ebdb0ab54c4075071b72568a40a75d0205.1736372610.git.mail@maciej.szmigiero.name


Signed-off-by: Jakub Kicinski <kuba@kernel.org>

parent 1da742e3

drivers/net/wwan/iosm/iosm_ipc_pcie.c

+55 −1

Original line number	Diff line number	Diff line
		@@ -6,6 +6,7 @@
		#include <linux/acpi.h>
		#include <linux/bitfield.h>
		#include <linux/module.h>
		#include <linux/suspend.h>
		#include <net/rtnetlink.h>

		#include "iosm_ipc_imem.h"
		@@ -18,6 +19,7 @@ MODULE_LICENSE("GPL v2");
		/* WWAN GUID */
		static guid_t wwan_acpi_guid = GUID_INIT(0xbad01b75, 0x22a8, 0x4f48, 0x87, 0x92,
		0xbd, 0xde, 0x94, 0x67, 0x74, 0x7d);
		static bool pci_registered;

		static void ipc_pcie_resources_release(struct iosm_pcie *ipc_pcie)
		{
		@@ -448,7 +450,6 @@ static struct pci_driver iosm_ipc_driver = {
		},
		.id_table = iosm_ipc_ids,
		};
		module_pci_driver(iosm_ipc_driver);

		int ipc_pcie_addr_map(struct iosm_pcie ipc_pcie, unsigned char data,
		size_t size, dma_addr_t *mapping, int direction)
		@@ -530,3 +531,56 @@ void ipc_pcie_kfree_skb(struct iosm_pcie ipc_pcie, struct sk_buff skb)
		IPC_CB(skb)->mapping = 0;
		dev_kfree_skb(skb);
		}

		static int pm_notify(struct notifier_block nb, unsigned long mode, void _unused)
		{
		if (mode == PM_HIBERNATION_PREPARE \|\| mode == PM_RESTORE_PREPARE) {
		if (pci_registered) {
		pci_unregister_driver(&iosm_ipc_driver);
		pci_registered = false;
		}
		} else if (mode == PM_POST_HIBERNATION \|\| mode == PM_POST_RESTORE) {
		if (!pci_registered) {
		int ret;

		ret = pci_register_driver(&iosm_ipc_driver);
		if (ret) {
		pr_err(KBUILD_MODNAME ": unable to re-register PCI driver: %d\n",
		ret);
		} else {
		pci_registered = true;
		}
		}
		}

		return 0;
		}

		static struct notifier_block pm_notifier = {
		.notifier_call = pm_notify,
		};

		static int __init iosm_ipc_driver_init(void)
		{
		int ret;

		ret = pci_register_driver(&iosm_ipc_driver);
		if (ret)
		return ret;

		pci_registered = true;

		register_pm_notifier(&pm_notifier);

		return 0;
		}
		module_init(iosm_ipc_driver_init);

		static void __exit iosm_ipc_driver_exit(void)
		{
		unregister_pm_notifier(&pm_notifier);

		if (pci_registered)
		pci_unregister_driver(&iosm_ipc_driver);
		}
		module_exit(iosm_ipc_driver_exit);