linux-kernel - Re: [PATCH 1/2] watchdog: sama5d4: Cache MR instead of a partial config

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Date:   Sat, 4 Feb 2017 15:55:36 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     Alexandre Belloni <alexandre.belloni@...e-electrons.com>
Cc:     Wim Van Sebroeck <wim@...ana.be>,
        Nicolas Ferre <nicolas.ferre@...el.com>,
        linux-watchdog@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] watchdog: sama5d4: Cache MR instead of a partial
 config

On 01/30/2017 09:18 AM, Alexandre Belloni wrote:
> .config is used to cache a part of WDT_MR at probe time and is not used
> afterwards. Instead of doing that, actually cache MR and avoid reading it
> every time it is modified.
>
> Signed-off-by: Alexandre Belloni <alexandre.belloni@...e-electrons.com>

Reviewed-by: Guenter Roeck <linux@...ck-us.net>

[ hoping that you'll remember to fix the problem in the set_timeout function ]

> ---
>  drivers/watchdog/sama5d4_wdt.c | 45 ++++++++++++++++++------------------------
>  1 file changed, 19 insertions(+), 26 deletions(-)
>
> diff --git a/drivers/watchdog/sama5d4_wdt.c b/drivers/watchdog/sama5d4_wdt.c
> index a49634cdc1cc..6dd07bef515a 100644
> --- a/drivers/watchdog/sama5d4_wdt.c
> +++ b/drivers/watchdog/sama5d4_wdt.c
> @@ -28,7 +28,7 @@
>  struct sama5d4_wdt {
>  	struct watchdog_device	wdd;
>  	void __iomem		*reg_base;
> -	u32	config;
> +	u32			mr;
>  };
>
>  static int wdt_timeout = WDT_DEFAULT_TIMEOUT;
> @@ -53,11 +53,9 @@ MODULE_PARM_DESC(nowayout,
>  static int sama5d4_wdt_start(struct watchdog_device *wdd)
>  {
>  	struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd);
> -	u32 reg;
>
> -	reg = wdt_read(wdt, AT91_WDT_MR);
> -	reg &= ~AT91_WDT_WDDIS;
> -	wdt_write(wdt, AT91_WDT_MR, reg);
> +	wdt->mr &= ~AT91_WDT_WDDIS;
> +	wdt_write(wdt, AT91_WDT_MR, wdt->mr);
>
>  	return 0;
>  }
> @@ -65,11 +63,9 @@ static int sama5d4_wdt_start(struct watchdog_device *wdd)
>  static int sama5d4_wdt_stop(struct watchdog_device *wdd)
>  {
>  	struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd);
> -	u32 reg;
>
> -	reg = wdt_read(wdt, AT91_WDT_MR);
> -	reg |= AT91_WDT_WDDIS;
> -	wdt_write(wdt, AT91_WDT_MR, reg);
> +	wdt->mr |= AT91_WDT_WDDIS;
> +	wdt_write(wdt, AT91_WDT_MR, wdt->mr);
>
>  	return 0;
>  }
> @@ -88,14 +84,12 @@ static int sama5d4_wdt_set_timeout(struct watchdog_device *wdd,
>  {
>  	struct sama5d4_wdt *wdt = watchdog_get_drvdata(wdd);
>  	u32 value = WDT_SEC2TICKS(timeout);
> -	u32 reg;
>
> -	reg = wdt_read(wdt, AT91_WDT_MR);
> -	reg &= ~AT91_WDT_WDV;
> -	reg &= ~AT91_WDT_WDD;
> -	reg |= AT91_WDT_SET_WDV(value);
> -	reg |= AT91_WDT_SET_WDD(value);
> -	wdt_write(wdt, AT91_WDT_MR, reg);
> +	wdt->mr &= ~AT91_WDT_WDV;
> +	wdt->mr &= ~AT91_WDT_WDD;
> +	wdt->mr |= AT91_WDT_SET_WDV(value);
> +	wdt->mr |= AT91_WDT_SET_WDD(value);
> +	wdt_write(wdt, AT91_WDT_MR, wdt->mr);
>
>  	wdd->timeout = timeout;
>
> @@ -132,19 +126,19 @@ static int of_sama5d4_wdt_init(struct device_node *np, struct sama5d4_wdt *wdt)
>  {
>  	const char *tmp;
>
> -	wdt->config = AT91_WDT_WDDIS;
> +	wdt->mr = AT91_WDT_WDDIS;
>
>  	if (!of_property_read_string(np, "atmel,watchdog-type", &tmp) &&
>  	    !strcmp(tmp, "software"))
> -		wdt->config |= AT91_WDT_WDFIEN;
> +		wdt->mr |= AT91_WDT_WDFIEN;
>  	else
> -		wdt->config |= AT91_WDT_WDRSTEN;
> +		wdt->mr |= AT91_WDT_WDRSTEN;
>
>  	if (of_property_read_bool(np, "atmel,idle-halt"))
> -		wdt->config |= AT91_WDT_WDIDLEHLT;
> +		wdt->mr |= AT91_WDT_WDIDLEHLT;
>
>  	if (of_property_read_bool(np, "atmel,dbg-halt"))
> -		wdt->config |= AT91_WDT_WDDBGHLT;
> +		wdt->mr |= AT91_WDT_WDDBGHLT;
>
>  	return 0;
>  }
> @@ -163,11 +157,10 @@ static int sama5d4_wdt_init(struct sama5d4_wdt *wdt)
>  	reg &= ~AT91_WDT_WDDIS;
>  	wdt_write(wdt, AT91_WDT_MR, reg);
>
> -	reg = wdt->config;
> -	reg |= AT91_WDT_SET_WDD(value);
> -	reg |= AT91_WDT_SET_WDV(value);
> +	wdt->mr |= AT91_WDT_SET_WDD(value);
> +	wdt->mr |= AT91_WDT_SET_WDV(value);
>
> -	wdt_write(wdt, AT91_WDT_MR, reg);
> +	wdt_write(wdt, AT91_WDT_MR, wdt->mr);
>
>  	return 0;
>  }
> @@ -211,7 +204,7 @@ static int sama5d4_wdt_probe(struct platform_device *pdev)
>  			return ret;
>  	}
>
> -	if ((wdt->config & AT91_WDT_WDFIEN) && irq) {
> +	if ((wdt->mr & AT91_WDT_WDFIEN) && irq) {
>  		ret = devm_request_irq(&pdev->dev, irq, sama5d4_wdt_irq_handler,
>  				       IRQF_SHARED | IRQF_IRQPOLL |
>  				       IRQF_NO_SUSPEND, pdev->name, pdev);
>