Hi, On Thu, Nov 14, 2013 at 11:05:16AM -0600, Nishanth Menon wrote: > OMAP device hooks around suspend|resume_noirq ensures that hwmod > devices are forced to idle using omap_device_idle/enable as part of > the last stage of suspend activity. > > For a device such as i2c who uses autosuspend, it is possible to enter > the suspend path with dev->power.runtime_status = RPM_ACTIVE. > > As part of the suspend flow, the generic runtime logic would increment > it's dev->power.disable_depth to 1. This should prevent further > pm_runtime_get_sync from succeeding once the runtime_status has been > set to RPM_SUSPENDED. > > Now, as part of the suspend_noirq handler in omap_device, we force the > following: if the device status is !suspended, we force the device > to idle using omap_device_idle (clocks are cut etc..). This ensures > that from a hardware perspective, the device is "suspended". However, > runtime_status is left to be active. > > *if* an operation is attempted after this point to > pm_runtime_get_sync, runtime framework depends on runtime_status to > indicate accurately the device status, and since it sees it to be > ACTIVE, it assumes the module is functional and returns a non-error > value. As a result the user will see pm_runtime_get succeed, however a > register access will crash due to the lack of clocks. > > To prevent this from happening, we should ensure that runtime_status > exactly indicates the device status. As a result of this change > any further calls to pm_runtime_get* would return -EACCES (since > disable_depth is 1). On resume, we restore the clocks and runtime > status exactly as we suspended with. These operations are not expected > to fail as we update the states after the core runtime framework has > suspended itself and restore before the core runtime framework has > resumed. > > Reported-by: J Keerthy <j-keerthy@xxxxxx> > Signed-off-by: Nishanth Menon <nm@xxxxxx> > Acked-by: Rajendra Nayak <rnayak@xxxxxx> > Acked-by: Kevin Hilman <khilman@xxxxxxxxxx> > --- > Changes in V3: > - Added WARN in case of unexpected failure of runtime pm status restore > v2: https://patchwork.kernel.org/patch/3176501/ > v1: https://patchwork.kernel.org/patch/3154501/ > > patch baseline: V3.12 tag (also applies on linux-next next-20131107 tag) > > arch/arm/mach-omap2/omap_device.c | 13 +++++++++++-- > 1 file changed, 11 insertions(+), 2 deletions(-) > > diff --git a/arch/arm/mach-omap2/omap_device.c b/arch/arm/mach-omap2/omap_device.c > index b69dd9a..53f0735 100644 > --- a/arch/arm/mach-omap2/omap_device.c > +++ b/arch/arm/mach-omap2/omap_device.c > @@ -621,6 +621,7 @@ static int _od_suspend_noirq(struct device *dev) > > if (!ret && !pm_runtime_status_suspended(dev)) { > if (pm_generic_runtime_suspend(dev) == 0) { > + pm_runtime_set_suspended(dev); > omap_device_idle(pdev); > od->flags |= OMAP_DEVICE_SUSPENDED; > } > @@ -634,10 +635,18 @@ static int _od_resume_noirq(struct device *dev) > struct platform_device *pdev = to_platform_device(dev); > struct omap_device *od = to_omap_device(pdev); > > - if ((od->flags & OMAP_DEVICE_SUSPENDED) && > - !pm_runtime_status_suspended(dev)) { > + if (od->flags & OMAP_DEVICE_SUSPENDED) { > od->flags &= ~OMAP_DEVICE_SUSPENDED; > omap_device_enable(pdev); > + /* > + * XXX: we run before core runtime pm has resumed itself. At > + * this point in time, we just restore the runtime pm state and > + * considering symmetric operations in resume, we donot expect > + * to fail. If we failed, something changed in core runtime_pm > + * framework OR some device driver messed things up, hence, WARN > + */ > + WARN(pm_runtime_set_active(dev), > + "Could not set %s runtime state active\n", dev_name(dev)); if you want to print the device name, how about dev_WARN() ? no strong feelings though: Reviewed-by: Felipe Balbi <balbi@xxxxxx> -- balbi
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