dev_pm_ops and PCMCIA sockets

Dominik Brodowski linux at
Mon Mar 15 11:50:36 EDT 2010


attempting to use the "new-style" dev_pm_ops to handle the suspend / resume
needs of PCMCIA sockets gives me a headache. Maybe you can assist me in
doing it properly?

(1) PCMCIA/CardBus sockets all share one class:
	 struct class pcmcia_socket_class
    The "class" devices (which are struct *device now) are registered in
    drivers/pcmcia/cs.c . The functional ordering is:

	struct device *dev	-- some PCMCIA/CardBus bridge

	struct device *dev	-- of class pcmcia_socket_class; represents
				   the socket. One bridge may have mutliple

	struct device *dev	-- of bus "pcmcia" or "pci"; represents the
				   PCMCIA/CardBus card. One card is in one
				   socket; but one card may have multiple
				   "pcmcia" or "pci" devices.

(2) For suspend, we need the following order:

	1) CardBus and PCMCIA cards themselves;
	   IRQs may be on.

	   For CardBus, this is well handled by the PCI subsystem; for
	   PCMCIA cards, we currently rely on an old-style "suspend"
	   callback in struct bus_type .

	2) the PCMCIA/CardBus socket ("class devices"); IRQs may be on

	   Currently, we rely on an ugly, custom callback mechanism. Quoting

	    * socket drivers are expected to use the following callbacks in
	    * their .drv struct:
	    *  - pcmcia_socket_dev_suspend
	    *  - pcmcia_socket_dev_resume
	    * These functions check for the appropriate struct pcmcia_soket arrays,
	    * and pass them to the low-level functions pcmcia_{suspend,resume}_socket

	3) The PCMCIA/CardBus bridge devices; both with IRQs on and off

	   For example, yenta_socket appropriately uses "struct dev_pm_ops".

(3) For resume, it's a bit more complicated:

	1) The PCMCIA/CardBus bridge devices with IRQs off

	2) The PCMCIA/CardBus sockets ("class devices") with IRQs off

	3) the PCMCIA/CardBus bridge devices with IRQs on

	4) The PCMCIA/CardBus sockets ("class devices") with IRQs on

	5) CardBus and PCMCIA cards themselves

(4) A first attempt to use struct dev_pm_ops in struct class pcmcia_socket_class

+ const struct dev_pm_ops pcmcia_socket_pm_ops = {
+ 	/* dev_suspend, dev_resume may be called with IRQs enabled */
+ 	SET_SYSTEM_SLEEP_PM_OPS(pcmcia_socket_classdev_suspend,
+ 				pcmcia_socket_classdev_resume)
+ 	/* early resume must be called with IRQs disabled */
+ 	.resume_noirq = pcmcia_socket_classdev_resume_noirq,
+ 	.thaw_noirq = pcmcia_socket_classdev_resume_noirq,
+ 	.restore_noirq = pcmcia_socket_classdev_resume_noirq,
+ };

    lead to the following issues:

     a) resume_noirq never got called. Haven't tried thaw_noirq and
	restore_noirq so far.

     b) If I read the information about ordering in Documentation/power/devices.txt
        correctly, even a functioning _noirq callback for classes would
	cause the order for suspend to be:

	- IRQs on, classes first, devices next:
		PCMCIA/CardBus socket (is 1, should be 2)
		PCMCIA/CardBus cards (is 2, should be 1)

		PCMCIA/CardBus bridge devices (is 3)

	- IRQs off:
		PCMCIA/CardBus bridge devices (is 3)

        and for resume to be:

	- IRQs off, devices first, classes next:

		PCMCIA/CardBus bridge devices (is 1)
		PCMCIA/CardBus socket         (is 2)

	- IRQs on, devices first, classes next:

		PCMCIA/CardBus bridge	      (is 3)
		PCMCIA/CardBus cards	      (is 4, should be 5)
		PCMCIA/CardBus socket	      (is 5, should be 4)

Any ideas on how to resolve these issues using the new-stlye dev_pm_ops?


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