Todd Poynor <toddpoy...@google.com> writes: > On Fri, Aug 12, 2011 at 12:20:21PM +0530, Munegowda, Keshava wrote: >> On Wed, Aug 10, 2011 at 10:01 PM, Todd Poynor <toddpoy...@google.com> wrote: >> >> @@ -913,12 +598,15 @@ static int usbhs_enable(struct device *dev) >> >> (pdata->ehci_data->reset_gpio_port[1], 1); >> >> } >> >> >> >> -end_count: >> >> - omap->count++; >> >> + pm_runtime_put_sync(dev); >> >> spin_unlock_irqrestore(&omap->lock, flags); >> > >> > Is pm_runtime_irq_safe() needed (else I think runtime PM callbacks may >> > re-enable IRQs... or there's the new *_suspend runtime PM calls that >> > may avoid this)? >> >> pm_runtime_irq_safe() is not required; usbhs does not have a parent >> and it is the parent driver of >> ehci and ohci drivers. > > But the above expects IRQs to be disabled during the > pm_runtime_put_sync, and synchronous calls can turn IRQs back on in > rpm_idle: > > if (callback) { > spin_unlock_irq(&dev->power.lock); > > callback(dev); > > I see other folks who know this better than me are discussing USB run > time PM and might_sleep contexts, so I'll note this concern and let > others chime in if they think there's a real problem here.
FYI... The commit below fixes this mainline (merged as of v3.1-rc4). Kevin commit 02b26774afebb2d62695ba3230319d70d8c6cc2d Author: Kevin Hilman <khil...@ti.com> Date: Fri Aug 5 21:45:20 2011 +0200 PM / Runtime: Allow _put_sync() from interrupts-disabled context Currently the use of pm_runtime_put_sync() is not safe from interrupts-disabled context because rpm_idle() will release the spinlock and enable interrupts for the idle callbacks. This enables interrupts during a time where interrupts were expected to be disabled, and can have strange side effects on drivers that expected interrupts to be disabled. This is not a bug since the documentation clearly states that only _put_sync_suspend() is safe in IRQ-safe mode. However, pm_runtime_put_sync() could be made safe when in IRQ-safe mode by releasing the spinlock but not re-enabling interrupts, which is what this patch aims to do. Problem was found when using some buggy drivers that set pm_runtime_irq_safe() and used _put_sync() in interrupts-disabled context. Reported-by: Colin Cross <ccr...@google.com> Tested-by: Nishanth Menon <n...@ti.com> Signed-off-by: Kevin Hilman <khil...@ti.com> Signed-off-by: Rafael J. Wysocki <r...@sisk.pl> -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html