linux-kernel - R: [PATCH 1/3] watchdog: qcom-wdt: add option to skip pretimeout

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Date:   Tue, 4 Feb 2020 17:16:34 +0100
From:   <ansuelsmth@...il.com>
To:     "'Guenter Roeck'" <linux@...ck-us.net>
Cc:     "'Andy Gross'" <agross@...nel.org>,
        "'Bjorn Andersson'" <bjorn.andersson@...aro.org>,
        "'Wim Van Sebroeck'" <wim@...ux-watchdog.org>,
        "'Rob Herring'" <robh+dt@...nel.org>,
        "'Mark Rutland'" <mark.rutland@....com>,
        <linux-arm-msm@...r.kernel.org>, <linux-watchdog@...r.kernel.org>,
        <devicetree@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: R: [PATCH 1/3] watchdog: qcom-wdt: add option to skip pretimeout

If something like this is used, msm-timer require interrupts. Without this
configuration, the device is unbootable as the system froze on system
bootup.

timer@...a000 {
			compatible = "qcom,kpss-timer", "qcom,msm-timer";
			interrupts = <GIC_PPI 1 (GIC_CPU_MASK_SIMPLE(2) |
						 IRQ_TYPE_EDGE_RISING)>,
				     <GIC_PPI 2 (GIC_CPU_MASK_SIMPLE(2) |
						 IRQ_TYPE_EDGE_RISING)>,
				     <GIC_PPI 3 (GIC_CPU_MASK_SIMPLE(2) |
						 IRQ_TYPE_EDGE_RISING)>,
				     <GIC_PPI 4 (GIC_CPU_MASK_SIMPLE(2) |
						 IRQ_TYPE_EDGE_RISING)>,
				     <GIC_PPI 5 (GIC_CPU_MASK_SIMPLE(2) |
						 IRQ_TYPE_EDGE_RISING)>;
			no-pretimeout;
			reg = <0x0200a000 0x100>;
			clock-frequency = <25000000>,
					  <32768>;
			clocks = <&sleep_clk>;
			clock-names = "sleep";
			cpu-offset = <0x80000>;
		};

> On Tue, Feb 04, 2020 at 04:21:01PM +0100, Ansuel Smith wrote:
> > Some platform like ipq806x doesn't support pretimeout.
> > As the driver check if there are available interrupts and ipq806x
> > use msm-timer that require interrupts, the watchdog fail to probe
> > as request_irq tries to use a ppi interrupt. Add an option to skip
> > pretimeout setup and use the normal watchdog probe.
> >
> > Signed-off-by: Ansuel Smith <ansuelsmth@...il.com>
> > ---
> >  drivers/watchdog/qcom-wdt.c | 5 ++++-
> >  1 file changed, 4 insertions(+), 1 deletion(-)
> >
> > diff --git a/drivers/watchdog/qcom-wdt.c b/drivers/watchdog/qcom-wdt.c
> > index a494543d3ae1..e689e97e883e 100644
> > --- a/drivers/watchdog/qcom-wdt.c
> > +++ b/drivers/watchdog/qcom-wdt.c
> > @@ -189,6 +189,7 @@ static int qcom_wdt_probe(struct platform_device
> *pdev)
> >  	u32 percpu_offset;
> >  	int irq, ret;
> >  	struct clk *clk;
> > +	bool nopretimeout;
> >
> >  	regs = of_device_get_match_data(dev);
> >  	if (!regs) {
> > @@ -204,6 +205,8 @@ static int qcom_wdt_probe(struct platform_device
> *pdev)
> >  	if (!res)
> >  		return -ENOMEM;
> >
> > +	nopretimeout = of_property_read_bool(np, "no-pretimeout");
> > +
> >  	/* We use CPU0's DGT for the watchdog */
> >  	if (of_property_read_u32(np, "cpu-offset", &percpu_offset))
> >  		percpu_offset = 0;
> > @@ -247,7 +250,7 @@ static int qcom_wdt_probe(struct platform_device
> *pdev)
> >
> >  	/* check if there is pretimeout support */
> >  	irq = platform_get_irq(pdev, 0);
> > -	if (irq > 0) {
> > +	if (!nopretimeout && irq > 0) {
> 
> That is unnecessary; such platforms should simply not provide an
interrupt.
> Or, in other words, what is the point of assigning an interrupt to be used
> for pretimeout if the platform doesn't support it ? And then to add yet
> another attribute to tell the driver not to use it ?
> 
> Guenter
> 
> >  		ret = devm_request_irq(dev, irq, qcom_wdt_isr,
> >  				       IRQF_TRIGGER_RISING,
> >  				       "wdt_bark", &wdt->wdd);
> > --
> > 2.24.0
> >