linux-kernel - Re: [PATCH v1 4/6] wdt: Support wdt on ROHM BD9576MUF and BD9573MUF

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <7c642388-68c9-a0aa-d661-93d13322240d@roeck-us.net>
Date:   Fri, 18 Sep 2020 18:49:59 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     "Vaittinen, Matti" <Matti.Vaittinen@...rohmeurope.com>,
        "mazziesaccount@...il.com" <mazziesaccount@...il.com>
Cc:     "wim@...ux-watchdog.org" <wim@...ux-watchdog.org>,
        "broonie@...nel.org" <broonie@...nel.org>,
        "devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
        linux-power <linux-power@...rohmeurope.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "lee.jones@...aro.org" <lee.jones@...aro.org>,
        "linux-watchdog@...r.kernel.org" <linux-watchdog@...r.kernel.org>,
        "lgirdwood@...il.com" <lgirdwood@...il.com>,
        "robh+dt@...nel.org" <robh+dt@...nel.org>
Subject: Re: [PATCH v1 4/6] wdt: Support wdt on ROHM BD9576MUF and BD9573MUF

On 9/17/20 11:06 PM, Vaittinen, Matti wrote:
> Thanks (again) for review Guenter!
> 
> On Thu, 2020-09-17 at 22:45 -0700, Guenter Roeck wrote:
>> On 9/17/20 1:03 AM, Matti Vaittinen wrote:
>>> Add Watchdog support for ROHM BD9576MUF and BD9573MUF PMICs which
>>> are
>>> mainly used to power the R-Car series processors. The watchdog is
>>> pinged using a GPIO and enabled using another GPIO. Additionally
>>> watchdog time-out can be configured to HW prior starting the
>>> watchdog.
>>> Watchdog timeout can be configured to detect only delayed ping or
>>> in
>>> a window mode where also too fast pings are detected.
>>>
>>> Signed-off-by: Matti Vaittinen <matti.vaittinen@...rohmeurope.com>
>>> ---
>>>  drivers/watchdog/Kconfig      |  13 ++
>>>  drivers/watchdog/Makefile     |   1 +
>>>  drivers/watchdog/bd9576_wdt.c | 295
>>> ++++++++++++++++++++++++++++++++++
>>>  3 files changed, 309 insertions(+)
>>>  create mode 100644 drivers/watchdog/bd9576_wdt.c
> 
>>
>>> +
>>> +	ret = of_property_read_u32(np,
>>> +				   "hw_margin_ms", &hw_margin);
>>
>> Line splits are arbitrary. Why is this "hw_margin_ms" and not
>> "rohm,hw_margin_ms" ?
> 
> "hw_margin_ms" is an existing binding for specifying the maximum TMO in
> HW (if I understood it correctly). (It is used at least by the generig
> GPIO watchdog) I thought it's better to not invent a new vendor
> specific binding when we have a generic one.
> 
> https://elixir.bootlin.com/linux/v5.9-rc2/source/Documentation/devicetree/bindings/watchdog/gpio-wdt.txt
> 
>>
>>> +	if (ret) {
>>> +		if (ret != -EINVAL)
>>> +			return ret;
>>> +
>>> +		hw_margin = BD957X_WDT_DEFAULT_MARGIN;
>>> +	}
>>> +
>>> +	ret = of_property_read_u32(np, "rohm,hw-margin-min-ms",
>>> &hw_margin_min);
>>> +	if (ret == -EINVAL)
>>> +		hw_margin_min = 0;
>>> +	else if (ret)
>>> +		return ret;
>>
>> Please use a single mechanism to handle -EINVAL after
>> of_property_read_u32().
> 
> Sorry Guenter - I am probably a bit slow today but I am unsure if I
> understand the suggestion. Do you mean something like:
> 

    if (ret) {
>>> +		if (ret != -EINVAL)
>>> +			return ret;
>>> +
>>> +		hw_margin = BD957X_WDT_DEFAULT_MARGIN;
>>> +	}

vs.

>>> +	if (ret == -EINVAL)
>>> +		hw_margin_min = 0;
>>> +	else if (ret)
>>> +		return ret;

is not very consistent to me.

Guenter

> hw_margin_min = 0;
> 
> ret = of_property_read_u32(np, "rohm,hw-margin-min-ms",
> &hw_margin_min);
> if (ret && ret != -EINVAL)
> 	return ret;
> 
> Other than that - all findings are clear to me. I'll craft a new
> version but I'll wait for a while to see if Lee has time to send some
> feedback on MFD so I could get both WDG and MFD fixes to same version
> :)
> 
> Best Regards
> 	--Matti
> 
> 
> --
> Matti Vaittinen, Linux device drivers
> ROHM Semiconductors, Finland
> SWDC
> Kiviharjunlenkki 1E
> 90220 OULU
> FINLAND
> 
> ~~~ "I don't think so," said Rene Descartes. Just then he vanished ~~~
> 
> Simon says - in Latin please.
> "non cogito me" dixit Rene Descarte, deinde evanescavit
> 
> (Thanks for the translation Simon)
>