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Message-ID: <20151124162344.GG807@x1>
Date: Tue, 24 Nov 2015 16:23:44 +0000
From: Lee Jones <lee.jones@...aro.org>
To: Jon Hunter <jonathanh@...dia.com>
Cc: linux-kernel@...r.kernel.org, linux-tegra@...r.kernel.org
Subject: Re: [PATCH V2] mfd: as3722: Handle interrupts on suspend
On Fri, 20 Nov 2015, Jon Hunter wrote:
> The as3722 device is registered as an irqchip and the as3722-rtc interrupt
> is one of it's interrupt sources. When using the as3722-rtc as a wake-up
> device from suspend, the following is seen:
>
> PM: Syncing filesystems ... done.
> Freezing user space processes ... (elapsed 0.001 seconds) done.
> Freezing remaining freezable tasks ... (elapsed 0.001 seconds) done.
> Suspending console(s) (use no_console_suspend to debug)
> PM: suspend of devices complete after 161.119 msecs
> PM: late suspend of devices complete after 1.048 msecs
> PM: noirq suspend of devices complete after 0.756 msecs
> Disabling non-boot CPUs ...
> CPU1: shutdown
> CPU2: shutdown
> CPU3: shutdown
> Entering suspend state LP1
> Enabling non-boot CPUs ...
> CPU1 is up
> CPU2 is up
> CPU3 is up
> PM: noirq resume of devices complete after 0.487 msecs
> as3722 4-0040: Failed to read IRQ status: -16
> as3722 4-0040: Failed to read IRQ status: -16
> as3722 4-0040: Failed to read IRQ status: -16
> as3722 4-0040: Failed to read IRQ status: -16
> ...
>
> The reason why the as3722 interrupt status cannot be read is because the
> as3722 interrupt is not masked during suspend and when the as3722-rtc
> interrupt occurs, to wake-up the device, the interrupt is seen before the
> i2c controller has been resumed in order to read the as3722 interrupt
> status.
>
> The as3722-rtc driver sets it's interrupt as a wake-up source during
> suspend, which gets propagated to the parent as3722 interrupt. However,
> the as3722-rtc driver cannot disable it's interrupt during suspend
> otherwise we would never be woken up and so the as3722 must disable it's
> interrupt instead.
>
> Fix this by disabling the as3722 interrupt during suspend. To ensure that
> a wake-up event from the as3722 is not missing, enable the as3722 interrupt
> as a wake-up source before disabling the interrupt on entering suspend.
>
> Signed-off-by: Jon Hunter <jonathanh@...dia.com>
> ---
>
> v2 changes:
> - Re-enabled the interrupt in resume before disabling the wake-up.
>
> drivers/mfd/as3722.c | 30 ++++++++++++++++++++++++++++++
> 1 file changed, 30 insertions(+)
Looks reasonable.
Applied, thanks.
> diff --git a/drivers/mfd/as3722.c b/drivers/mfd/as3722.c
> index 924ea90494ae..3b21eb4bc480 100644
> --- a/drivers/mfd/as3722.c
> +++ b/drivers/mfd/as3722.c
> @@ -405,6 +405,8 @@ static int as3722_i2c_probe(struct i2c_client *i2c,
> goto scrub;
> }
>
> + device_init_wakeup(as3722->dev, true);
> +
> dev_dbg(as3722->dev, "AS3722 core driver initialized successfully\n");
> return 0;
>
> @@ -422,6 +424,29 @@ static int as3722_i2c_remove(struct i2c_client *i2c)
> return 0;
> }
>
> +static int as3722_i2c_suspend(struct device *dev)
> +{
> + struct as3722 *as3722 = dev_get_drvdata(dev);
> +
> + if (device_may_wakeup(dev))
> + enable_irq_wake(as3722->chip_irq);
> + disable_irq(as3722->chip_irq);
> +
> + return 0;
> +}
> +
> +static int as3722_i2c_resume(struct device *dev)
> +{
> + struct as3722 *as3722 = dev_get_drvdata(dev);
> +
> + enable_irq(as3722->chip_irq);
> +
> + if (device_may_wakeup(dev))
> + disable_irq_wake(as3722->chip_irq);
> +
> + return 0;
> +}
> +
> static const struct of_device_id as3722_of_match[] = {
> { .compatible = "ams,as3722", },
> {},
> @@ -434,10 +459,15 @@ static const struct i2c_device_id as3722_i2c_id[] = {
> };
> MODULE_DEVICE_TABLE(i2c, as3722_i2c_id);
>
> +static const struct dev_pm_ops as3722_pm_ops = {
> + SET_SYSTEM_SLEEP_PM_OPS(as3722_i2c_suspend, as3722_i2c_resume)
> +};
> +
> static struct i2c_driver as3722_i2c_driver = {
> .driver = {
> .name = "as3722",
> .of_match_table = as3722_of_match,
> + .pm = &as3722_pm_ops,
> },
> .probe = as3722_i2c_probe,
> .remove = as3722_i2c_remove,
--
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
Follow Linaro: Facebook | Twitter | Blog
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