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    SubjectRe: Solving suspend-level confusion
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    On Sat, 2004-07-31 at 02:44, Pavel Machek wrote:
    > Hi!
    >
    > There's quite big confusion what 'u32 state' in suspend callbacks
    > mean. Half code interprets it as a system-wide suspend level, and
    > second half thinks it is PCI Dx state. Bad.
    >
    > What about this solution:
    >
    > * system-wide suspend level is always passed down (it is more
    > detailed, and for example IDE driver cares)
    >
    > * if you want to derive Dx state, just use provided inline function to
    > convert.
    >
    > That should be acceptable to everyone. I plan on explicitly using
    > enums to prevent further confusion. Patch is likely to be pretty big:
    > ideally all prototypes of suspend function would be fixed so noone can
    > be confused.
    >
    > What do you think?

    Your constants are ugly ;) But the whole idea makes sense, I've started
    implementing something on my side, though I didn't change the u32 to an
    enum to avoid having to "fix" bazillions of drivers. Proper
    documentation may just be enough...
    Pavel
    > PS: I'll be on holidays for a week, feel free to implement this or
    > something similar.. it is going to be lot of search/replace in drivers
    > :-(.

    I'll have some patches soon along with the PPC stuff.


    > --- tmp/linux/include/linux/pci.h 2004-06-22 12:36:45.000000000 +0200
    > +++ linux/include/linux/pci.h 2004-07-30 18:24:02.000000000 +0200
    > @@ -593,7 +593,7 @@
    > const struct pci_device_id *id_table; /* must be non-NULL for probe to be called */
    > int (*probe) (struct pci_dev *dev, const struct pci_device_id *id); /* New device inserted */
    > void (*remove) (struct pci_dev *dev); /* Device removed (NULL if not a hot-plug capable driver) */
    > - int (*suspend) (struct pci_dev *dev, u32 state); /* Device suspended */
    > + int (*suspend) (struct pci_dev *dev, enum suspend_state reason); /* Device suspended */
    > int (*resume) (struct pci_dev *dev); /* Device woken up */
    > int (*enable_wake) (struct pci_dev *dev, u32 state, int enable); /* Enable wake event */
    >
    > --- tmp/linux/include/linux/pm.h 2004-06-22 12:36:45.000000000 +0200
    > +++ linux/include/linux/pm.h 2004-07-30 18:23:11.000000000 +0200
    > @@ -193,11 +193,11 @@
    > extern void (*pm_idle)(void);
    > extern void (*pm_power_off)(void);
    >
    > -enum {
    > - PM_SUSPEND_ON,
    > - PM_SUSPEND_STANDBY,
    > - PM_SUSPEND_MEM,
    > - PM_SUSPEND_DISK,
    > +enum system_state {
    > + PM_SUSPEND_ON = 0,
    > + PM_SUSPEND_STANDBY = 1,
    > + PM_SUSPEND_MEM = 2,
    > + PM_SUSPEND_DISK = 3,
    > PM_SUSPEND_MAX,
    > };
    >
    > @@ -241,11 +240,47 @@
    >
    > extern void device_pm_set_parent(struct device * dev, struct device * parent);
    >
    > -extern int device_suspend(u32 state);
    > -extern int device_power_down(u32 state);
    > +enum suspend_state {
    > + SNAPSHOT = 10, /* For debugging, symbolic constants should be everywhere */
    > + POWERDOWN,
    > + RESTART,
    > + RUNTIME_D1,
    > + RUNTIME_D2,
    > + RUNTIME_D3hot,
    > + RUNTIME_D3cold
    > +};
    > +
    > +extern int device_suspend(enum suspend_state reason);
    > +extern int device_power_down(enum suspend_state reason);
    > extern void device_power_up(void);
    > extern void device_resume(void);
    >
    > +enum pci_state {
    > + D0 = 20, /* For debugging, symbolic constants should be everywhere */
    > + D1,
    > + D2,
    > + D3hot,
    > + D3cold
    > +};
    > +
    > +static inline enum pci_state to_pci_state(enum suspend_state state)
    > +{
    > + switch(state) {
    > + case RUNTIME_D1:
    > + return D1;
    > + case RUNTIME_D2:
    > + return D2;
    > + case RUNTIME_D3hot:
    > + return D3hot;
    > + case SNAPSHOT:
    > + case POWERDOWN:
    > + case RESTART:
    > + case RUNTIME_D3cold:
    > + return D3cold;
    > + default:
    > + BUG();
    > + }
    > +}
    >
    > #endif /* __KERNEL__ */
    >
    > --- tmp/linux/kernel/power/disk.c 2004-05-20 23:08:36.000000000 +0200
    > +++ linux/kernel/power/disk.c 2004-07-30 18:18:04.000000000 +0200
    > @@ -46,20 +46,25 @@
    > int error = 0;
    >
    > local_irq_save(flags);
    > - device_power_down(PM_SUSPEND_DISK);
    > switch(mode) {
    > case PM_DISK_PLATFORM:
    > + device_power_down(POWERDOWN);
    > error = pm_ops->enter(PM_SUSPEND_DISK);
    > break;
    > case PM_DISK_SHUTDOWN:
    > + device_power_down(POWERDOWN);
    > printk("Powering off system\n");
    > machine_power_off();
    > break;
    > case PM_DISK_REBOOT:
    > + device_power_down(RESTART);
    > machine_restart(NULL);
    > break;
    > }
    > machine_halt();
    > + /* Valid image is on the disk, if we continue we risk serious data corruption
    > + after resume. */
    > + while(1);
    > device_power_up();
    > local_irq_restore(flags);
    > return 0;
    --
    Benjamin Herrenschmidt <benh@kernel.crashing.org>

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