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Message-ID: <c488ef1f-0ce1-23d7-8105-89efd0f5a769@roeck-us.net>
Date: Sun, 19 Feb 2017 08:53:52 -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 v2 1/3] watchdog: sama5d4: Cleanup init
On 02/17/2017 07:35 AM, Alexandre Belloni wrote:
> On 17/02/2017 at 06:48:36 -0800, Guenter Roeck wrote:
>> On 02/16/2017 11:30 AM, Alexandre Belloni wrote:
>>> .config is used to cache a part of WDT_MR at probe time and is not used
>>> afterwards. Also functions are used while they always return 0. Simplify
>>> the flow by having everything in .probe().
>>>
>>
>> Does that really improve anything ? It makes the code harder to read
>> and, ultimately, the dropped value in sama5d4_wdt is added back in a
>> later patch as 'mr'.
>>
>
> I don't find the current code to be particularly easy to read but maybe
> it is a matter of taste.
>
I always thought it is commonly accepted that splitting code into smaller
functions tends to improve readability. I for my part still think it does,
and splitting out reading configuration data and initializing the chip
are good candidates.
[ Not that the functions are necessarily named well here, but that is
a different issue ]
> I would still remove the test on pdev->dev.of_node because it will never
> be false anyway.
>
Agreed.
Guenter
>
>> Guenter
>>
>>> Signed-off-by: Alexandre Belloni <alexandre.belloni@...e-electrons.com>
>>> ---
>>> Changes in v2:
>>> - completely get rid of .config instead of caching it
>>> - merge init functions in probe()
>>>
>>> drivers/watchdog/sama5d4_wdt.c | 92 ++++++++++++++++--------------------------
>>> 1 file changed, 34 insertions(+), 58 deletions(-)
>>>
>>> diff --git a/drivers/watchdog/sama5d4_wdt.c b/drivers/watchdog/sama5d4_wdt.c
>>> index a49634cdc1cc..2c6f5a70ae67 100644
>>> --- a/drivers/watchdog/sama5d4_wdt.c
>>> +++ b/drivers/watchdog/sama5d4_wdt.c
>>> @@ -28,7 +28,6 @@
>>> struct sama5d4_wdt {
>>> struct watchdog_device wdd;
>>> void __iomem *reg_base;
>>> - u32 config;
>>> };
>>>
>>> static int wdt_timeout = WDT_DEFAULT_TIMEOUT;
>>> @@ -128,57 +127,15 @@ static irqreturn_t sama5d4_wdt_irq_handler(int irq, void *dev_id)
>>> return IRQ_HANDLED;
>>> }
>>>
>>> -static int of_sama5d4_wdt_init(struct device_node *np, struct sama5d4_wdt *wdt)
>>> -{
>>> - const char *tmp;
>>> -
>>> - wdt->config = AT91_WDT_WDDIS;
>>> -
>>> - if (!of_property_read_string(np, "atmel,watchdog-type", &tmp) &&
>>> - !strcmp(tmp, "software"))
>>> - wdt->config |= AT91_WDT_WDFIEN;
>>> - else
>>> - wdt->config |= AT91_WDT_WDRSTEN;
>>> -
>>> - if (of_property_read_bool(np, "atmel,idle-halt"))
>>> - wdt->config |= AT91_WDT_WDIDLEHLT;
>>> -
>>> - if (of_property_read_bool(np, "atmel,dbg-halt"))
>>> - wdt->config |= AT91_WDT_WDDBGHLT;
>>> -
>>> - return 0;
>>> -}
>>> -
>>> -static int sama5d4_wdt_init(struct sama5d4_wdt *wdt)
>>> -{
>>> - struct watchdog_device *wdd = &wdt->wdd;
>>> - u32 value = WDT_SEC2TICKS(wdd->timeout);
>>> - u32 reg;
>>> -
>>> - /*
>>> - * Because the fields WDV and WDD must not be modified when the WDDIS
>>> - * bit is set, so clear the WDDIS bit before writing the WDT_MR.
>>> - */
>>> - reg = wdt_read(wdt, AT91_WDT_MR);
>>> - 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_write(wdt, AT91_WDT_MR, reg);
>>> -
>>> - return 0;
>>> -}
>>> -
>>> static int sama5d4_wdt_probe(struct platform_device *pdev)
>>> {
>>> struct watchdog_device *wdd;
>>> struct sama5d4_wdt *wdt;
>>> struct resource *res;
>>> void __iomem *regs;
>>> - u32 irq = 0;
>>> + struct device_node *np = pdev->dev.of_node;
>>> + const char *tmp;
>>> + u32 mr, reg, irq = 0;
>>> int ret;
>>>
>>> wdt = devm_kzalloc(&pdev->dev, sizeof(*wdt), GFP_KERNEL);
>>> @@ -201,17 +158,26 @@ static int sama5d4_wdt_probe(struct platform_device *pdev)
>>>
>>> wdt->reg_base = regs;
>>>
>>> - if (pdev->dev.of_node) {
>>> - irq = irq_of_parse_and_map(pdev->dev.of_node, 0);
>>> - if (!irq)
>>> - dev_warn(&pdev->dev, "failed to get IRQ from DT\n");
>>> + irq = irq_of_parse_and_map(np, 0);
>>> + if (!irq)
>>> + dev_warn(&pdev->dev, "failed to get IRQ from DT\n");
>>>
>>> - ret = of_sama5d4_wdt_init(pdev->dev.of_node, wdt);
>>> - if (ret)
>>> - return ret;
>>> - }
>>>
>>> - if ((wdt->config & AT91_WDT_WDFIEN) && irq) {
>>> + mr = AT91_WDT_WDDIS;
>>> +
>>> + if (!of_property_read_string(np, "atmel,watchdog-type", &tmp) &&
>>> + !strcmp(tmp, "software"))
>>> + mr |= AT91_WDT_WDFIEN;
>>> + else
>>> + mr |= AT91_WDT_WDRSTEN;
>>> +
>>> + if (of_property_read_bool(np, "atmel,idle-halt"))
>>> + mr |= AT91_WDT_WDIDLEHLT;
>>> +
>>> + if (of_property_read_bool(np, "atmel,dbg-halt"))
>>> + mr |= AT91_WDT_WDDBGHLT;
>>> +
>>> + if ((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);
>>> @@ -228,9 +194,19 @@ static int sama5d4_wdt_probe(struct platform_device *pdev)
>>> return ret;
>>> }
>>>
>>> - ret = sama5d4_wdt_init(wdt);
>>> - if (ret)
>>> - return ret;
>>> + /*
>>> + * WDV and WDD must not be modified when the WDDIS bit is set, so clear
>>> + * the WDDIS bit before writing the WDT_MR.
>>> + */
>>> + reg = wdt_read(wdt, AT91_WDT_MR);
>>> + reg &= ~AT91_WDT_WDDIS;
>>> + wdt_write(wdt, AT91_WDT_MR, reg);
>>> +
>>> + reg = mr;
>>> + reg |= AT91_WDT_SET_WDD(WDT_SEC2TICKS(wdd->timeout));
>>> + reg |= AT91_WDT_SET_WDV(WDT_SEC2TICKS(wdd->timeout));
>>> +
>>> + wdt_write(wdt, AT91_WDT_MR, reg);
>>>
>>> watchdog_set_nowayout(wdd, nowayout);
>>>
>>>
>>
>
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