On 16:38-20131107, Kevin Hilman wrote: [...] > That's debatable I guess. The ideal world is that runtime PM hides all > of this, but I'm not sure it's achievable in all cases. > Agreed. some drivers like edma need to save and restore context around suspend. [...] > No, that sysfs knob is for disabling runtime PM. We still want the > device to hit low-power state in system suspend. Solving that problem > is half the reason we have this omap_device noirq mess in the first > place. > > You need to test this by disabling runtime PM from userspace and ensure > that the low power state is still hit during suspend. > Done and it still does work, makes sense since it just ensures that runtime PM's dev->power.runtime_status is set to RPM_SUSPENDED instead of RPM_ACTIVE for devices that depend on autosuspend. Logs (based on vendor kernel which has relevant out of tree patches to enable suspend resume - still in the works): AM335x-BBB: http://pastie.org/8472182 OMAP5-uEVM: http://pastie.org/8472183 > >> > >>> + /* NOTE: *might* indicate driver race */ > >> > >> Yes, a driver race which should then be fixed in the driver. > > > > true if this is a non-autosuspend device, in auto suspend devices, > > this could be a regular phenomenon if timeout is pretty large.. but > > atleast that should allow debug. > > Agreed. I wasn't thinking about the autosuspend case. Thanks for > clarifying. > > >> > >>> + dev_dbg(dev, "%s: Force suspending\n", > >>> + __func__); > >>> + pm_runtime_set_suspended(dev); > >>> + od->flags |= OMAP_DEVICE_SUSPEND_FORCED; > >> > >> Not sure why you need an additonal flag. Why not just always do this > >> and use the existin OMAP_DEVICE_SUSPENDED flag. > > > > restore of runtime data structure state is only needed for specific > > devices - not all.. > > The question is why do you a flag in addition to OMAP_DEVICE_SUSPEND. > Whenever that flag is set, omap_device has gone behind your back, and > the runtime PM status should be kept in sync. Yes, you are right, originally, I had intended this to indicate devices that needed to be runtime_status updated, but then, now I realize that it is true for all devices that have OMAP_DEVICE_SUSPEND set. It can be applied without an additional flag. Do see if the updated patch is more sensible: -- >8 -- >From 96b5a7b89fef4ba55bca48bae83e5536d697c6c4 Mon Sep 17 00:00:00 2001 From: Nishanth Menon <nm@xxxxxx> Date: Thu, 24 Oct 2013 09:12:42 -0500 Subject: [PATCH V2] ARM: OMAP2+: omap_device: maintain sane runtime pm status around suspend/resume 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. Reported-by: J Keerthy <j-keerthy@xxxxxx> Signed-off-by: Nishanth Menon <nm@xxxxxx> Acked-by: Rajendra Nayak <rnayak@xxxxxx> --- arch/arm/mach-omap2/omap_device.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/arch/arm/mach-omap2/omap_device.c b/arch/arm/mach-omap2/omap_device.c index b69dd9a..f97b34b 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 +635,10 @@ 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); + pm_runtime_set_active(dev); pm_generic_runtime_resume(dev); } -- 1.7.9.5 -- Regards, Nishanth Menon -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
