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SubjectRe: [PATCH 2/3] watchdog: orion: don't enable rstout if an interrupt is configured
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On 10/10/2017 07:29 PM, Chris Packham wrote:
> The orion_wdt_irq invokes panic() so we are going to reset the CPU
> regardless. By not setting this bit we get a chance to gather debug
> from the panic output before the system is reset.
>
> Signed-off-by: Chris Packham <chris.packham@alliedtelesis.co.nz>

Unless I am missing something, this assumes that the interrupt is
handled, ie that the system is not stuck with interrupts disabled.
This makes the watchdog less reliable. This added verbosity comes
at a significant cost. I'd like to get input from others if this
is acceptable.

That would be different if there was a means to configure a pretimeout,
ie a means to tell the system to generate an irq first, followed by a
hard reset if the interrupt is not served. that does not seem to be
the case here, though.

Guenter

> ---
> drivers/watchdog/orion_wdt.c | 25 +++++++++++++++++--------
> 1 file changed, 17 insertions(+), 8 deletions(-)
>
> diff --git a/drivers/watchdog/orion_wdt.c b/drivers/watchdog/orion_wdt.c
> index ea676d233e1e..ce88f339ef7f 100644
> --- a/drivers/watchdog/orion_wdt.c
> +++ b/drivers/watchdog/orion_wdt.c
> @@ -71,6 +71,7 @@ struct orion_watchdog {
> unsigned long clk_rate;
> struct clk *clk;
> const struct orion_watchdog_data *data;
> + int irq;
> };
>
> static int orion_wdt_clock_init(struct platform_device *pdev,
> @@ -203,9 +204,11 @@ static int armada375_start(struct watchdog_device *wdt_dev)
> dev->data->wdt_enable_bit);
>
> /* Enable reset on watchdog */
> - reg = readl(dev->rstout);
> - reg |= dev->data->rstout_enable_bit;
> - writel(reg, dev->rstout);
> + if (!dev->irq) {
> + reg = readl(dev->rstout);
> + reg |= dev->data->rstout_enable_bit;
> + writel(reg, dev->rstout);
> + }
>
> atomic_io_modify(dev->rstout_mask, dev->data->rstout_mask_bit, 0);
> return 0;
> @@ -228,9 +231,12 @@ static int armada370_start(struct watchdog_device *wdt_dev)
> dev->data->wdt_enable_bit);
>
> /* Enable reset on watchdog */
> - reg = readl(dev->rstout);
> - reg |= dev->data->rstout_enable_bit;
> - writel(reg, dev->rstout);
> + if (!dev->irq) {
> + reg = readl(dev->rstout);
> + reg |= dev->data->rstout_enable_bit;
> + writel(reg, dev->rstout);
> + }
> +
> return 0;
> }
>
> @@ -247,8 +253,9 @@ static int orion_start(struct watchdog_device *wdt_dev)
> dev->data->wdt_enable_bit);
>
> /* Enable reset on watchdog */
> - atomic_io_modify(dev->rstout, dev->data->rstout_enable_bit,
> - dev->data->rstout_enable_bit);
> + if (!dev->irq)
> + atomic_io_modify(dev->rstout, dev->data->rstout_enable_bit,
> + dev->data->rstout_enable_bit);
>
> return 0;
> }
> @@ -595,6 +602,8 @@ static int orion_wdt_probe(struct platform_device *pdev)
> dev_err(&pdev->dev, "failed to request IRQ\n");
> goto disable_clk;
> }
> +
> + dev->irq = irq;
> }
>
> watchdog_set_nowayout(&dev->wdt, nowayout);
>

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