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SubjectRe: [RFC PATCH v2 1/3] PCI: rockchip: Add support for pcie wake irq
+ Tony

On Thu, Aug 17, 2017 at 08:04:29PM +0800, Jeffy Chen wrote:
> Add support for PCIE_WAKE pin in rockchip pcie driver.
>
> Signed-off-by: Jeffy Chen <jeffy.chen@rock-chips.com>
> ---
>
> Changes in v2:
> Use dev_pm_set_dedicated_wake_irq
> -- Suggested by Brian Norris <briannorris@chromium.com>
>
> drivers/pci/host/pcie-rockchip.c | 13 ++++++++++++-
> 1 file changed, 12 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/pci/host/pcie-rockchip.c b/drivers/pci/host/pcie-rockchip.c
> index 7bb9870f6d8c..c2b973c738fe 100644
> --- a/drivers/pci/host/pcie-rockchip.c
> +++ b/drivers/pci/host/pcie-rockchip.c
> @@ -36,6 +36,7 @@
> #include <linux/pci_ids.h>
> #include <linux/phy/phy.h>
> #include <linux/platform_device.h>
> +#include <linux/pm_wakeirq.h>
> #include <linux/reset.h>
> #include <linux/regmap.h>
>
> @@ -853,7 +854,6 @@ static void rockchip_pcie_legacy_int_handler(struct irq_desc *desc)
> chained_irq_exit(chip, desc);
> }
>
> -
> /**
> * rockchip_pcie_parse_dt - Parse Device Tree
> * @rockchip: PCIe port information
> @@ -1018,6 +1018,14 @@ static int rockchip_pcie_parse_dt(struct rockchip_pcie *rockchip)
> return err;
> }
>
> + device_init_wakeup(dev, true);
> + irq = platform_get_irq_byname(pdev, "wake");
> + if (irq >= 0) {
> + err = dev_pm_set_dedicated_wake_irq(dev, irq);

Did you test that this works out correctly as a level-triggered
interrupt? IIUC, the dummy handler won't mask the interrupt, so it might
keep firing. See:

static irqreturn_t handle_threaded_wake_irq(int irq, void *_wirq)
{
struct wake_irq *wirq = _wirq;
int res;

/* Maybe abort suspend? */
if (irqd_is_wakeup_set(irq_get_irq_data(irq))) {
pm_wakeup_event(wirq->dev, 0);

return IRQ_HANDLED; <--- We can return here, with the trigger still asserted
}
...

This could cause some kind of an IRQ storm, including a lockup or
significant slowdown, I think.

BTW, in another context, Tony suggested we might need to fix up the IRQ flags
like this:

int dev_pm_set_dedicated_wake_irq(struct device *dev, int irq)
{
...
err = request_threaded_irq(irq, NULL, handle_threaded_wake_irq,
- IRQF_ONESHOT, dev_name(dev), wirq);
+ IRQF_ONESHOT | irq_get_trigger_type(irq), dev_name(dev), wirq);

But IIUC, that's not actually necessary, because __setup_irq()
automatically configures the trigger type if the driver didn't request
one explicitly.

Brian

> + if (err)
> + dev_err(dev, "failed to setup PCIe wake IRQ\n");
> + }
> +
> rockchip->vpcie3v3 = devm_regulator_get_optional(dev, "vpcie3v3");
> if (IS_ERR(rockchip->vpcie3v3)) {
> if (PTR_ERR(rockchip->vpcie3v3) == -EPROBE_DEFER)
> @@ -1524,6 +1532,9 @@ static int rockchip_pcie_remove(struct platform_device *pdev)
> struct device *dev = &pdev->dev;
> struct rockchip_pcie *rockchip = dev_get_drvdata(dev);
>
> + dev_pm_clear_wake_irq(dev);
> + device_init_wakeup(dev, false);
> +
> pci_stop_root_bus(rockchip->root_bus);
> pci_remove_root_bus(rockchip->root_bus);
> pci_unmap_iospace(rockchip->io);
> --
> 2.11.0
>
>

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