linux-kernel - Re: [PATCH v2] i2c: smbus: Send alert notifications to all devices if source not found

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Message-ID: <Zq-QCvhEhk_Bd3xG@shikoro>
Date: Sun, 4 Aug 2024 16:28:26 +0200
From: Wolfram Sang <wsa+renesas@...g-engineering.com>
To: Guenter Roeck <linux@...ck-us.net>
Cc: linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2] i2c: smbus: Send alert notifications to all devices
 if source not found

On Tue, Jul 30, 2024 at 07:19:41AM -0700, Guenter Roeck wrote:
> If a SMBUs alert is received and the originating device is not found,

Fixed this capital 'U' while applying.

> the reason may be that the address reported on the SMBus alert address
> is corrupted, for example because multiple devices asserted alert and
> do not correctly implement SMBus arbitration.
> 
> If this happens, call alert handlers on all devices connected to the
> given I2C bus, in the hope that this cleans up the situation.
> 
> This change reliably fixed the problem on a system with multiple devices
> on a single bus. Example log where the device on address 0x18 (ADM1021)
> and on address 0x4c (ADT7461A) both had the alert line asserted:
> 
> smbus_alert 3-000c: SMBALERT# from dev 0x0c, flag 0
> smbus_alert 3-000c: no driver alert()!
> smbus_alert 3-000c: SMBALERT# from dev 0x0c, flag 0
> smbus_alert 3-000c: no driver alert()!
> lm90 3-0018: temp1 out of range, please check!
> lm90 3-0018: Disabling ALERT#
> lm90 3-0029: Everything OK
> lm90 3-002a: Everything OK
> lm90 3-004c: temp1 out of range, please check!
> lm90 3-004c: temp2 out of range, please check!
> lm90 3-004c: Disabling ALERT#
> 
> Fixes: b5527a7766f0 ("i2c: Add SMBus alert support")
> Signed-off-by: Guenter Roeck <linux@...ck-us.net>

Applied to for-current, thanks!

> -		 * the loop because it will never terminate.
> -		 * Bail out in this case.
> +		 * the loop because it will never terminate. Try again, this
> +		 * time calling the alert handlers of all devices connected to
> +		 * the bus, and abort the loop afterwards. If this helps, we
> +		 * are all set. If it doesn't, there is nothing else we can do,
> +		 * so we might as well abort the loop.

I really like this updated comment. Kudos!


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