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Message-ID: <20170816174936.GB99323@google.com>
Date: Wed, 16 Aug 2017 10:49:37 -0700
From: Brian Norris <briannorris@...omium.org>
To: Jeffy Chen <jeffy.chen@...k-chips.com>
Cc: linux-kernel@...r.kernel.org, bhelgaas@...gle.com,
shawn.lin@...k-chips.com, dianders@...omium.org,
Heiko Stuebner <heiko@...ech.de>, linux-pci@...r.kernel.org,
linux-rockchip@...ts.infradead.org,
linux-arm-kernel@...ts.infradead.org
Subject: Re: [RFC PATCH 1/3] PCI: rockchip: Add support for pcie wake irq
Hi,
On Wed, Aug 16, 2017 at 03:52:22PM +0800, Jeffy Chen wrote:
> Add support for PCIE_WAKE pin in rockchip pcie driver.
>
> Signed-off-by: Jeffy Chen <jeffy.chen@...k-chips.com>
> ---
>
> drivers/pci/host/pcie-rockchip.c | 58 ++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 58 insertions(+)
>
> diff --git a/drivers/pci/host/pcie-rockchip.c b/drivers/pci/host/pcie-rockchip.c
> index 7bb9870f6d8c..f969a6d3cd85 100644
> --- a/drivers/pci/host/pcie-rockchip.c
> +++ b/drivers/pci/host/pcie-rockchip.c
> @@ -38,6 +38,7 @@
> #include <linux/platform_device.h>
> #include <linux/reset.h>
> #include <linux/regmap.h>
> +#include <linux/suspend.h>
>
> /*
> * The upper 16 bits of PCIE_CLIENT_CONFIG are a write mask for the lower 16
> @@ -226,6 +227,8 @@ struct rockchip_pcie {
> struct regulator *vpcie1v8; /* 1.8V power supply */
> struct regulator *vpcie0v9; /* 0.9V power supply */
> struct gpio_desc *ep_gpio;
> + int wake_irq;
> + bool wake_by_pcie;
> u32 lanes;
> u8 root_bus_nr;
> int link_gen;
> @@ -853,6 +856,20 @@ static void rockchip_pcie_legacy_int_handler(struct irq_desc *desc)
> chained_irq_exit(chip, desc);
> }
>
> +static irqreturn_t rockchip_pcie_wake_irq_handler(int irq, void *arg)
> +{
> + struct rockchip_pcie *rockchip = arg;
> +
> + rockchip->wake_by_pcie = true;
> +
> + disable_irq_nosync(rockchip->wake_irq);
> + disable_irq_wake(rockchip->wake_irq);
> +
> + pm_wakeup_event(rockchip->dev, 0);
> + pm_system_wakeup();
> +
> + return IRQ_HANDLED;
> +}
>
> /**
> * rockchip_pcie_parse_dt - Parse Device Tree
> @@ -868,6 +885,7 @@ static int rockchip_pcie_parse_dt(struct rockchip_pcie *rockchip)
> struct resource *regs;
> int irq;
> int err;
> + bool wakeup = 0;
'0' should be 'false'.
>
> regs = platform_get_resource_byname(pdev,
> IORESOURCE_MEM,
> @@ -1018,6 +1036,21 @@ static int rockchip_pcie_parse_dt(struct rockchip_pcie *rockchip)
> return err;
> }
>
> + rockchip->wake_irq = platform_get_irq_byname(pdev, "wake");
> + if (rockchip->wake_irq >= 0) {
> + err = devm_request_irq(dev, rockchip->wake_irq,
> + rockchip_pcie_wake_irq_handler,
> + 0, "pcie-wake", rockchip);
> + if (err) {
> + dev_err(dev, "failed to request PCIe wake IRQ\n");
> + return err;
> + }
> +
> + disable_irq(rockchip->wake_irq);
If you're worried about keeping this disabled at first, you can just use
this nifty trick (since this isn't a shared interrupt) -- call this
before requesting the IRQ:
irq_set_status_flags(rockchip->wake_irq, IRQ_NOAUTOEN);
You could also consider using dev_pm_set_dedicated_wake_irq() to handle
this -- but beware, it still might not quite handle level-triggered
interrupt properly. I'm pretty sure Tony Lindgren would be happy to get
testing or patches for that though :) He already sent me something a
while back but I didn't have time to test it out.
> + wakeup = device_property_read_bool(dev, "wakeup-source");
> + }
> + device_init_wakeup(dev, wakeup);
Shouldn't you call 'device_init_wakeup(dev, false)' on remove()?
> +
> rockchip->vpcie3v3 = devm_regulator_get_optional(dev, "vpcie3v3");
> if (IS_ERR(rockchip->vpcie3v3)) {
> if (PTR_ERR(rockchip->vpcie3v3) == -EPROBE_DEFER)
> @@ -1270,6 +1303,30 @@ static int rockchip_pcie_wait_l2(struct rockchip_pcie *rockchip)
> return 0;
> }
>
> +static int __maybe_unused rockchip_pcie_suspend(struct device *dev)
Why do this in suspend() instead of suspend_noirq()? You shouldn't
really need a separate method here.
Note that this should be a level-triggered interrupt which remains
asserted, so there should be no chance of "missing" it if you don't
enable it in time.
And on a related note: if you try the dedicated wake irq approach, this
will only occur just before the noirq phase anyway, since
device_wakeup_arm_wake_irqs() is called in dpm_suspend_noirq().
> +{
> + struct rockchip_pcie *rockchip = dev_get_drvdata(dev);
> +
> + rockchip->wake_by_pcie = false;
> +
> + if (device_may_wakeup(dev)) {
> + enable_irq_wake(rockchip->wake_irq);
> + enable_irq(rockchip->wake_irq);
> + }
> + return 0;
> +}
> +
> +static int __maybe_unused rockchip_pcie_resume(struct device *dev)
> +{
> + struct rockchip_pcie *rockchip = dev_get_drvdata(dev);
> +
> + if (device_may_wakeup(dev) && !rockchip->wake_by_pcie) {
The use of 'wake_by_pcie' is racy; an interrupt could be in flight (but
not completed), and so it could set 'wake_by_pcie' just after you're
reading this. Then, you'll get a double-disable.
I believe the safe way to handle this would be to use an atomic
test-and-set / test-and-clear approach (either atomic_cmpxchg(), or use
a spinlock).
> + disable_irq(rockchip->wake_irq);
> + disable_irq_wake(rockchip->wake_irq);
> + }
> + return 0;
> +}
> +
> static int __maybe_unused rockchip_pcie_suspend_noirq(struct device *dev)
> {
> struct rockchip_pcie *rockchip = dev_get_drvdata(dev);
> @@ -1548,6 +1605,7 @@ static int rockchip_pcie_remove(struct platform_device *pdev)
> }
>
> static const struct dev_pm_ops rockchip_pcie_pm_ops = {
> + SET_SYSTEM_SLEEP_PM_OPS(rockchip_pcie_suspend, rockchip_pcie_resume)
> SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(rockchip_pcie_suspend_noirq,
> rockchip_pcie_resume_noirq)
> };
Brian
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