linux-kernel - Re: [PATCH v3 4/6] hwmon: (pmbus/core) clear faults after setting smbalert mask

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Message-ID: <2a5c17c9-db8c-492d-87e7-c9872b2d5100@roeck-us.net>
Date: Mon, 4 Nov 2024 05:51:26 -0800
From: Guenter Roeck <linux@...ck-us.net>
To: Jerome Brunet <jbrunet@...libre.com>
Cc: Jean Delvare <jdelvare@...e.com>, Jonathan Corbet <corbet@....net>,
 Patrick Rudolph <patrick.rudolph@...ements.com>,
 Naresh Solanki <naresh.solanki@...ements.com>, Rob Herring
 <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>,
 Conor Dooley <conor+dt@...nel.org>,
 Delphine CC Chiu <Delphine_CC_Chiu@...ynn.com>, linux-hwmon@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
 devicetree@...r.kernel.org, linux-i2c@...r.kernel.org
Subject: Re: [PATCH v3 4/6] hwmon: (pmbus/core) clear faults after setting
 smbalert mask

On 11/4/24 00:28, Jerome Brunet wrote:
> On Fri 01 Nov 2024 at 08:10, Guenter Roeck <linux@...ck-us.net> wrote:
> 
>> On Thu, Oct 24, 2024 at 08:10:38PM +0200, Jerome Brunet wrote:
>>> pmbus_write_smbalert_mask() ignores the errors if the chip can't set
>>> smbalert mask the standard way. It is not necessarily a problem for the irq
>>> support if the chip is otherwise properly setup but it may leave an
>>> uncleared fault behind.
>>>
>>> pmbus_core will pick the fault on the next register_check(). The register
>>> check will fails regardless of the actual register support by the chip.
>>>
>>> This leads to missing attributes or debugfs entries for chips that should
>>> provide them.
>>>
>>> We cannot rely on register_check() as PMBUS_SMBALERT_MASK may be read-only.
>>>
>>> Unconditionally clear the page fault after setting PMBUS_SMBALERT_MASK to
>>> avoid the problem.
>>>
>>> Suggested-by: Guenter Roeck <linux@...ck-us.net>
>>> Fixes: 221819ca4c36 ("hwmon: (pmbus/core) Add interrupt support")
>>> Signed-off-by: Jerome Brunet <jbrunet@...libre.com>
>>> ---
>>>   drivers/hwmon/pmbus/pmbus_core.c | 7 ++++++-
>>>   1 file changed, 6 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/hwmon/pmbus/pmbus_core.c b/drivers/hwmon/pmbus/pmbus_core.c
>>> index ce697ca03de01c0e5a352f8f6b72671137721868..a0a397d571caa1a6620ef095f9cf63d94e8bda1d 100644
>>> --- a/drivers/hwmon/pmbus/pmbus_core.c
>>> +++ b/drivers/hwmon/pmbus/pmbus_core.c
>>> @@ -3346,7 +3346,12 @@ static int pmbus_regulator_notify(struct pmbus_data *data, int page, int event)
>>>   
>>>   static int pmbus_write_smbalert_mask(struct i2c_client *client, u8 page, u8 reg, u8 val)
>>>   {
>>> -	return _pmbus_write_word_data(client, page, PMBUS_SMBALERT_MASK, reg | (val << 8));
>>> +	int ret;
>>> +
>>> +	ret = _pmbus_write_word_data(client, page, PMBUS_SMBALERT_MASK, reg | (val << 8));
>>> +	pmbus_clear_fault_page(client, -1);
>>
>> Why -1 and not page ?
> 
> The idea was to clear the fault on the page we are on, basically just skipping
> setting the page again.
> 
> I'll change to 'page'
> 
Or just add a comment explaining the '-1'.

Thanks,
Guenter