linux-kernel - Re: [PATCH 1/2] watchdog: pm8916_wdt: fix pretimeout registration flow

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Date:   Sun, 8 Sep 2019 15:50:00 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Jorge Ramirez-Ortiz <jorge.ramirez-ortiz@...aro.org>,
        wim@...ux-watchdog.org
Cc:     linux-watchdog@...r.kernel.org, linux-kernel@...r.kernel.org,
        bjorn.andersson@...aro.org, Loic Poulain <loic.poulain@...aro.org>
Subject: Re: [PATCH 1/2] watchdog: pm8916_wdt: fix pretimeout registration
 flow

On 9/6/19 1:30 PM, Jorge Ramirez-Ortiz wrote:
> When an IRQ is present in the dts, the probe function shall fail if
> the interrupt can not be registered.
> 

The author intended differently, and did not want registration to fail
in this situation, following the logic that it is better to have a
standard watchdog without pretimeout than no watchdog at all.

Copying the author; I am not inclined to accept such a change without
input from the driver author.

Similar, for the deferred probe, we'll need to know from the driver author
if this is a concern. In general it is, but there are cases where
-EPROBE_DEFFER is never returned in practice (eg for some SoC watchdog
drivers).

Guenter

> The probe function shall also be retried if getting the irq is being
> deferred.
> 
> Signed-off-by: Jorge Ramirez-Ortiz <jorge.ramirez-ortiz@...aro.org>
> ---
>   drivers/watchdog/pm8916_wdt.c | 16 ++++++++++++----
>   1 file changed, 12 insertions(+), 4 deletions(-)
> 
> diff --git a/drivers/watchdog/pm8916_wdt.c b/drivers/watchdog/pm8916_wdt.c
> index 2d3652004e39..cb5304c26ac3 100644
> --- a/drivers/watchdog/pm8916_wdt.c
> +++ b/drivers/watchdog/pm8916_wdt.c
> @@ -163,9 +163,18 @@ static int pm8916_wdt_probe(struct platform_device *pdev)
>   
>   	irq = platform_get_irq(pdev, 0);
>   	if (irq > 0) {
> -		if (devm_request_irq(dev, irq, pm8916_wdt_isr, 0, "pm8916_wdt",
> -				     wdt))
> -			irq = 0;
> +		err = devm_request_irq(dev, irq, pm8916_wdt_isr, 0,
> +				       "pm8916_wdt", wdt);
> +		if (err)
> +			return err;
> +
> +		wdt->wdev.info = &pm8916_wdt_pt_ident;
> +
> +	} else {
> +		if (irq == -EPROBE_DEFER)
> +			return -EPROBE_DEFER;
> +
> +		wdt->wdev.info = &pm8916_wdt_ident;
>   	}
>   
>   	/* Configure watchdog to hard-reset mode */
> @@ -177,7 +186,6 @@ static int pm8916_wdt_probe(struct platform_device *pdev)
>   		return err;
>   	}
>   
> -	wdt->wdev.info = (irq > 0) ? &pm8916_wdt_pt_ident : &pm8916_wdt_ident,
>   	wdt->wdev.ops = &pm8916_wdt_ops,
>   	wdt->wdev.parent = dev;
>   	wdt->wdev.min_timeout = PM8916_WDT_MIN_TIMEOUT;
>