linux-kernel - Re: [PATCH v2 2/3] watchdog: sprd: check busy bit before new loading rather than after that

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Message-ID: <5cd5eadd-e1d1-7f6d-b993-106c0fe94d7d@roeck-us.net>
Date:   Sun, 8 Nov 2020 08:29:38 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     Chunyan Zhang <zhang.lyra@...il.com>,
        Wim Van Sebroeck <wim@...ux-watchdog.org>
Cc:     linux-watchdog@...r.kernel.org, linux-kernel@...r.kernel.org,
        Orson Zhai <orsonzhai@...il.com>,
        Baolin Wang <baolin.wang7@...il.com>,
        Chunyan Zhang <chunyan.zhang@...soc.com>,
        Lingling Xu <ling_ling.xu@...soc.com>,
        Jingchao Ye <jingchao.ye@...soc.com>,
        Xiaoqing Wu <xiaoqing.wu@...soc.com>
Subject: Re: [PATCH v2 2/3] watchdog: sprd: check busy bit before new loading
 rather than after that

On 10/28/20 7:39 PM, Chunyan Zhang wrote:
> From: Lingling Xu <ling_ling.xu@...soc.com>
> 
> As the specification described, users must check busy bit before start
> a new loading operation to make sure that the previous loading is done
> and the device is ready to accept a new one.
> 
> [ chunyan: Massaged changelog ]
> 
> Fixes: 477603467009 ("watchdog: Add Spreadtrum watchdog driver")
> Signed-off-by: Lingling Xu <ling_ling.xu@...soc.com>
> Signed-off-by: Chunyan Zhang <chunyan.zhang@...soc.com>

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

> ---
>  drivers/watchdog/sprd_wdt.c | 25 +++++++++++++------------
>  1 file changed, 13 insertions(+), 12 deletions(-)
> 
> diff --git a/drivers/watchdog/sprd_wdt.c b/drivers/watchdog/sprd_wdt.c
> index f3c90b4afead..b9b1daa9e2a4 100644
> --- a/drivers/watchdog/sprd_wdt.c
> +++ b/drivers/watchdog/sprd_wdt.c
> @@ -108,18 +108,6 @@ static int sprd_wdt_load_value(struct sprd_wdt *wdt, u32 timeout,
>  	u32 tmr_step = timeout * SPRD_WDT_CNT_STEP;
>  	u32 prtmr_step = pretimeout * SPRD_WDT_CNT_STEP;
>  
> -	sprd_wdt_unlock(wdt->base);
> -	writel_relaxed((tmr_step >> SPRD_WDT_CNT_HIGH_SHIFT) &
> -		      SPRD_WDT_LOW_VALUE_MASK, wdt->base + SPRD_WDT_LOAD_HIGH);
> -	writel_relaxed((tmr_step & SPRD_WDT_LOW_VALUE_MASK),
> -		       wdt->base + SPRD_WDT_LOAD_LOW);
> -	writel_relaxed((prtmr_step >> SPRD_WDT_CNT_HIGH_SHIFT) &
> -			SPRD_WDT_LOW_VALUE_MASK,
> -		       wdt->base + SPRD_WDT_IRQ_LOAD_HIGH);
> -	writel_relaxed(prtmr_step & SPRD_WDT_LOW_VALUE_MASK,
> -		       wdt->base + SPRD_WDT_IRQ_LOAD_LOW);
> -	sprd_wdt_lock(wdt->base);
> -
>  	/*
>  	 * Waiting the load value operation done,
>  	 * it needs two or three RTC clock cycles.
> @@ -134,6 +122,19 @@ static int sprd_wdt_load_value(struct sprd_wdt *wdt, u32 timeout,
>  
>  	if (delay_cnt >= SPRD_WDT_LOAD_TIMEOUT)
>  		return -EBUSY;
> +
> +	sprd_wdt_unlock(wdt->base);
> +	writel_relaxed((tmr_step >> SPRD_WDT_CNT_HIGH_SHIFT) &
> +		      SPRD_WDT_LOW_VALUE_MASK, wdt->base + SPRD_WDT_LOAD_HIGH);
> +	writel_relaxed((tmr_step & SPRD_WDT_LOW_VALUE_MASK),
> +		       wdt->base + SPRD_WDT_LOAD_LOW);
> +	writel_relaxed((prtmr_step >> SPRD_WDT_CNT_HIGH_SHIFT) &
> +			SPRD_WDT_LOW_VALUE_MASK,
> +		       wdt->base + SPRD_WDT_IRQ_LOAD_HIGH);
> +	writel_relaxed(prtmr_step & SPRD_WDT_LOW_VALUE_MASK,
> +		       wdt->base + SPRD_WDT_IRQ_LOAD_LOW);
> +	sprd_wdt_lock(wdt->base);
> +
>  	return 0;
>  }
>  
>