netdev - Re: [PATCH net-next 3/3] net: phy: realtek: add hwmon support for temp sensor on RTL822x

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: <6996e709-ef77-4fc6-ba78-1ccac40c3fb0@roeck-us.net>
Date: Fri, 10 Jan 2025 16:08:08 -0800
From: Guenter Roeck <linux@...ck-us.net>
To: Andrew Lunn <andrew@...n.ch>, Heiner Kallweit <hkallweit1@...il.com>
Cc: Russell King - ARM Linux <linux@...linux.org.uk>,
 Paolo Abeni <pabeni@...hat.com>, Jakub Kicinski <kuba@...nel.org>,
 David Miller <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>,
 Simon Horman <horms@...nel.org>,
 "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
 "linux-hwmon@...r.kernel.org" <linux-hwmon@...r.kernel.org>,
 Jean Delvare <jdelvare@...e.com>
Subject: Re: [PATCH net-next 3/3] net: phy: realtek: add hwmon support for
 temp sensor on RTL822x

On 1/10/25 13:10, Andrew Lunn wrote:
>> - over-temp alarm remains set, even if temperature drops below threshold
> 
>> +int rtl822x_hwmon_init(struct phy_device *phydev)
>> +{
>> +	struct device *hwdev, *dev = &phydev->mdio.dev;
>> +	const char *name;
>> +
>> +	/* Ensure over-temp alarm is reset. */
>> +	phy_clear_bits_mmd(phydev, MDIO_MMD_VEND2, RTL822X_VND2_TSALRM, 3);
> 
> So it is possible to clear the alarm.
> 
> I know you wanted to experiment with this some more....
> 
> If the alarm is still set, does that prevent the PHY renegotiating the
> higher link speed? If you clear the alarm, does that allow it to
> renegotiate the higher link speed? Or is a down/up still required?
> Does an down/up clear the alarm if the temperature is below the
> threshold?
> 
> Also, does HWMON support clearing alarms? Writing a 0 to the file? Or
> are they supported to self clear on read?
> 

Alarm attributes are supposed to self clear on read unless the condition
persists.

> I'm wondering if we are heading towards ABI issues? You have defined:
> 
> - over-temp alarm remains set, even if temperature drops below threshold
> 
> so that kind of eliminates the possibility of implementing self
> clearing any time in the future. Explicit clearing via a write is
> probably O.K, because the user needs to take an explicit action.  Are
> there other ABI issues i have not thought about.
> 

Alarm attributes are supposed to be read-only.

Guenter