From: Guenter Roeck <linux@roeck-us.net>
To: Luca Ceresoli <luca@lucaceresoli.net>
Cc: linux-kernel@vger.kernel.org, Lee Jones <lee.jones@linaro.org>,
Rob Herring <robh+dt@kernel.org>,
Chanwoo Choi <cw00.choi@samsung.com>,
Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com>,
Alessandro Zummo <a.zummo@towertech.it>,
Alexandre Belloni <alexandre.belloni@bootlin.com>,
Wim Van Sebroeck <wim@linux-watchdog.org>,
devicetree@vger.kernel.org, linux-rtc@vger.kernel.org,
linux-watchdog@vger.kernel.org,
Chiwoong Byun <woong.byun@samsung.com>,
Laxman Dewangan <ldewangan@nvidia.com>,
Randy Dunlap <rdunlap@infradead.org>
Subject: Re: [PATCH v4 7/9] watchdog: max77620: add support for the max77714 variant
Date: Mon, 29 Nov 2021 13:56:04 -0800 [thread overview]
Message-ID: <65a9c26d-31cb-7c4c-df87-12aee8f43578@roeck-us.net> (raw)
In-Reply-To: <8efe5354-6308-4f0c-a0c8-6657f705cfb1@lucaceresoli.net>
On 11/29/21 1:24 PM, Luca Ceresoli wrote:
[ ... ]
>>>
>>> +static const struct max77620_variant max77620_wdt_data = {
>>> + .wdt_info = {
>>> + .identity = "max77620-watchdog",
>>> + .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | WDIOF_MAGICCLOSE,
>>> + },
>>
>> That does not have to be, and should not be, part of device specific data,
>> just because of the identity string.
>
> Ok, no problem, will fix, but I have two questions.
>
> First, what's the reason? Coding style or a functional difference?
> Usually const data is preferred to runtime assignment.
>
wdt_info is not chip specific variant information as nothing but the identity
string is different, and there is no technical need for that difference.
> Second: it's not clear how you expect it to be done. Looking into the
I gave you three options to pick from.
> kernel it looks like almost all drivers set a constant string. I could
> find only one exception, f71808e_wdt:
> https://elixir.bootlin.com/linux/v5.16-rc3/source/drivers/watchdog/f71808e_wdt.c#L471
>
>> Either keep the current identity string,
>> mark max77620_wdt_info as __ro_after_init and overwrite the identity string
>> there during probe
>
> And also remove 'static' I guess. Hm, I don't love this, as above I tend
> to prefer static const when possible for file-scoped data.
>
Where did I suggest to remove 'static', and what would be the benefit of making
the variable global ?
>> or add the structure to max77620_wdt and fill it out there.
>
> Do you mean like the following, untested, kind-of-pseudocode?
>
> struct max77620_wdt {
> struct device *dev;
> struct regmap *rmap;
> const struct max77620_variant *drv_data;
> + struct watchdog_info info; /* not a pointer! */
> struct watchdog_device wdt_dev;
> };
>
> and then, in probe:
>
> wdt->dev = dev;
> wdt->drv_data = (const struct max77620_variant *)id->driver_data;
> /* ... assign other wdt fields ... */
> + strlcpy(wdt_dev->info.identity, id->name, \
> + sizeof(wdt_dev->info.identity));
> + wdt_dev->info.options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | \
> + WDIOF_MAGICCLOSE;
>
For example, yes.
> Finally, what about simply:
>
> static const struct max77620_variant max77620_wdt_data = {
> .wdt_info = {
> - .identity = "max77620-watchdog",
> + .identity = "max77xxx-watchdog",
> .options = WDIOF_SETTIMEOUT | WDIOF_KEEPALIVEPING | ...
> },
>
> and always use that struct unconditionally? The max63xx_wdt.c driver
> seems to do that. Or, if this is an issue for backward compatibility (is
> it?), just leave max77620_wdt_data and the .identity field will always
> be "max77620-watchdog" even when using a MAX77714.
Also ok with me.
Guenter
next prev parent reply other threads:[~2021-11-29 22:41 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-11-20 15:56 [PATCH v4 0/9] Add MAX77714 PMIC minimal driver (RTC and watchdog only) Luca Ceresoli
2021-11-20 15:56 ` [PATCH v4 1/9] rtc: max77686: convert comments to kernel-doc format Luca Ceresoli
2021-11-20 15:57 ` [PATCH v4 2/9] rtc: max77686: rename day-of-month defines Luca Ceresoli
2021-11-20 15:57 ` [PATCH v4 3/9] rtc: max77686: remove unused code to read in 12-hour mode Luca Ceresoli
2021-11-20 15:57 ` [PATCH v4 4/9] dt-bindings: mfd: add Maxim MAX77714 PMIC Luca Ceresoli
2021-11-21 16:48 ` Krzysztof Kozlowski
2021-11-20 15:57 ` [PATCH v4 5/9] mfd: max77714: Add driver for " Luca Ceresoli
2021-11-21 17:20 ` Krzysztof Kozlowski
2021-11-20 15:57 ` [PATCH v4 6/9] watchdog: Kconfig: fix help text indentation Luca Ceresoli
2021-11-20 15:57 ` [PATCH v4 7/9] watchdog: max77620: add support for the max77714 variant Luca Ceresoli
2021-11-29 15:53 ` Guenter Roeck
2021-11-29 21:24 ` Luca Ceresoli
2021-11-29 21:56 ` Guenter Roeck [this message]
2021-11-29 22:14 ` Luca Ceresoli
2021-11-20 15:57 ` [PATCH v4 8/9] watchdog: max77620: add comment to clarify set_timeout procedure Luca Ceresoli
2021-11-29 16:04 ` Guenter Roeck
2021-11-29 16:08 ` Luca Ceresoli
2021-11-29 16:18 ` Guenter Roeck
2021-11-20 15:57 ` [PATCH v4 9/9] rtc: max77686: add MAX77714 support Luca Ceresoli
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