linux-kernel - Re: [PATCH 2/2] i2c: smbus: Send alert notifications to all devices if source not found

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Message-ID: <c58ca576-2763-4f73-bc0e-c33677c5228b@roeck-us.net>
Date: Mon, 29 Jul 2024 11:44:26 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: Wolfram Sang <wsa+renesas@...g-engineering.com>,
 Wolfram Sang <wsa@...nel.org>, Jean Delvare <khali@...ux-fr.org>,
 linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] i2c: smbus: Send alert notifications to all devices
 if source not found

On 7/29/24 11:36, Wolfram Sang wrote:
> 
>> I looked into the code again. The sequence is (or is supposed to be):
>>
>> 1st loop:
>> 	if (!alert_pending)
>> 		break;
>> 	smbus_do_alert()
>> 	if (failed at same address)
>> 		smbus_do_alert_force()
>>
>> 2nd loop:
>> 	if (!alert_pending)
>> 		break;
>> 	smbus_do_alert()
>> 	if (failed at same address)
>> 		break;
>>
>> I think what you are suggesting is
> ...
> 
> What I am suggesting is more like this:
> 
> 1st loop:
> 
>   	smbus_do_alert()
> 	//impossible to have same address on first run, so go to 2nd loop
> 
> 2nd loop:
> 
>   	smbus_do_alert()
>   	if (failed at same address)
>   		smbus_do_alert_force()
> 		break;
> 
> As I understand it, your sequence is missing "my" 1st loop with the
> invalid address, so you will end up having 3 loops altogether?
> 
> The code I am suggesting is bascially yours without the retries
> variable:
> 
> 	status = device_for_each_child(&ara->adapter->dev, &data,
> 				       smbus_do_alert);
> 	if (data.addr == prev_addr && status != -EBUSY) {
> 		device_for_each_child(&ara->adapter->dev, &data,
> 				      smbus_do_alert_force);
> 		break;
> 	}
> 	prev_addr = data.addr;
> 
> Makes sense or am I missing something?
> 

Yes, that should work and is indeed simpler. You are correct, the
additional loop should not be necessary since smbus_do_alert_force()
should already call all connected drivers and hopefully clear
the alert condition on those.

Thanks,
Guenter