| Message ID | 1410533779-3310-2-git-send-email-k.kozlowski@samsung.com (mailing list archive) |
|---|---|
| State | Superseded |
| Headers | show |
On Fri, Sep 12, 2014 at 04:56:18PM +0200, Krzysztof Kozlowski wrote: > The AMBA bus driver defines runtime Power Management functions which > disable and unprepare AMBA bus clock. This is problematic for runtime PM > because unpreparing a clock might sleep so it is not interrupt safe. > > However some drivers may want to implement runtime PM functions in > interrupt-safe way (see pm_runtime_irq_safe()). If such driver > implements its own runtime PM functions then assume it will handle the > runtime PM completely and it will replace our clock handling. > > Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com> Actually, I'd rather just revert 5303c0f46c8708fff4148ebcc491f78710356952 which is clearly the wrong thing to do when we have non-IRQ safe runtime PM. What we /could/ do instead is to check whether irq_safe is set after probe, record that, and then select whether to use the prepare/unprepare methods based on that. (Drivers should never dynamically change this.)
On pi?, 2014-09-12 at 16:13 +0100, Russell King - ARM Linux wrote: > On Fri, Sep 12, 2014 at 04:56:18PM +0200, Krzysztof Kozlowski wrote: > > The AMBA bus driver defines runtime Power Management functions which > > disable and unprepare AMBA bus clock. This is problematic for runtime PM > > because unpreparing a clock might sleep so it is not interrupt safe. > > > > However some drivers may want to implement runtime PM functions in > > interrupt-safe way (see pm_runtime_irq_safe()). If such driver > > implements its own runtime PM functions then assume it will handle the > > runtime PM completely and it will replace our clock handling. > > > > Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com> > > Actually, I'd rather just revert 5303c0f46c8708fff4148ebcc491f78710356952 > which is clearly the wrong thing to do when we have non-IRQ safe runtime > PM. > > What we /could/ do instead is to check whether irq_safe is set after > probe, record that, and then select whether to use the prepare/unprepare > methods based on that. (Drivers should never dynamically change this.) I'll try this approach. Thank you for feedback, Krzysztof -- To unsubscribe from this list: send the line "unsubscribe dmaengine" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/amba/bus.c b/drivers/amba/bus.c index 3cf61a127ee5..38461430b7cf 100644 --- a/drivers/amba/bus.c +++ b/drivers/amba/bus.c @@ -94,9 +94,18 @@ static int amba_pm_runtime_suspend(struct device *dev) struct amba_device *pcdev = to_amba_device(dev); int ret = pm_generic_runtime_suspend(dev); - if (ret == 0 && dev->driver) + if (ret == 0 && dev->driver) { + /* + * If driver handles runtime suspend don't duplicate + * the work here. + */ + if (dev->driver->pm && dev->driver->pm->runtime_suspend) + goto out; + clk_disable_unprepare(pcdev->pclk); + } +out: return ret; } @@ -106,12 +115,16 @@ static int amba_pm_runtime_resume(struct device *dev) int ret; if (dev->driver) { + if (dev->driver->pm && dev->driver->pm->runtime_resume) + goto out; + ret = clk_prepare_enable(pcdev->pclk); /* Failure is probably fatal to the system, but... */ if (ret) return ret; } +out: return pm_generic_runtime_resume(dev); } #endif
The AMBA bus driver defines runtime Power Management functions which disable and unprepare AMBA bus clock. This is problematic for runtime PM because unpreparing a clock might sleep so it is not interrupt safe. However some drivers may want to implement runtime PM functions in interrupt-safe way (see pm_runtime_irq_safe()). If such driver implements its own runtime PM functions then assume it will handle the runtime PM completely and it will replace our clock handling. Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com> --- drivers/amba/bus.c | 15 ++++++++++++++- 1 file changed, 14 insertions(+), 1 deletion(-)