Update Linux to v5.4.2
Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/drivers/pci/hotplug/TODO b/drivers/pci/hotplug/TODO
new file mode 100644
index 0000000..a32070b
--- /dev/null
+++ b/drivers/pci/hotplug/TODO
@@ -0,0 +1,74 @@
+Contributions are solicited in particular to remedy the following issues:
+
+cpcihp:
+
+* There are no implementations of the ->hardware_test, ->get_power and
+ ->set_power callbacks in struct cpci_hp_controller_ops. Why were they
+ introduced? Can they be removed from the struct?
+
+cpqphp:
+
+* The driver spawns a kthread cpqhp_event_thread() which is woken by the
+ hardirq handler cpqhp_ctrl_intr(). Convert this to threaded IRQ handling.
+ The kthread is also woken from the timer pushbutton_helper_thread(),
+ convert it to call irq_wake_thread(). Use pciehp as a template.
+
+* A large portion of cpqphp_ctrl.c and cpqphp_pci.c concerns resource
+ management. Doesn't this duplicate functionality in the core?
+
+ibmphp:
+
+* Implementations of hotplug_slot_ops callbacks such as get_adapter_present()
+ in ibmphp_core.c create a copy of the struct slot on the stack, then perform
+ the actual operation on that copy. Determine if this overhead is necessary,
+ delete it if not. The functions also perform a NULL pointer check on the
+ struct hotplug_slot, this seems superfluous.
+
+* Several functions access the pci_slot member in struct hotplug_slot even
+ though pci_hotplug.h declares it private. See get_max_bus_speed() for an
+ example. Either the pci_slot member should no longer be declared private
+ or ibmphp should store a pointer to its bus in struct slot. Probably the
+ former.
+
+* The functions get_max_adapter_speed() and get_bus_name() are commented out.
+ Can they be deleted? There are also forward declarations at the top of
+ ibmphp_core.c as well as pointers in ibmphp_hotplug_slot_ops, likewise
+ commented out.
+
+* ibmphp_init_devno() takes a struct slot **, it could instead take a
+ struct slot *.
+
+* The return value of pci_hp_register() is not checked.
+
+* iounmap(io_mem) is called in the error path of ebda_rsrc_controller()
+ and once more in the error path of its caller ibmphp_access_ebda().
+
+* The various slot data structures are difficult to follow and need to be
+ simplified. A lot of functions are too large and too complex, they need
+ to be broken up into smaller, manageable pieces. Negative examples are
+ ebda_rsrc_controller() and configure_bridge().
+
+* A large portion of ibmphp_res.c and ibmphp_pci.c concerns resource
+ management. Doesn't this duplicate functionality in the core?
+
+sgi_hotplug:
+
+* Several functions access the pci_slot member in struct hotplug_slot even
+ though pci_hotplug.h declares it private. See sn_hp_destroy() for an
+ example. Either the pci_slot member should no longer be declared private
+ or sgi_hotplug should store a pointer to it in struct slot. Probably the
+ former.
+
+shpchp:
+
+* There is only a single implementation of struct hpc_ops. Can the struct be
+ removed and its functions invoked directly? This has already been done in
+ pciehp with commit 82a9e79ef132 ("PCI: pciehp: remove hpc_ops"). Clarify
+ if there was a specific reason not to apply the same change to shpchp.
+
+* The ->get_mode1_ECC_cap callback in shpchp_hpc_ops is never invoked.
+ Why was it introduced? Can it be removed?
+
+* The hardirq handler shpc_isr() queues events on a workqueue. It can be
+ simplified by converting it to threaded IRQ handling. Use pciehp as a
+ template.