linux-kernel - Re: [PATCH v2 4/4] hwmon: (pmbus/core): Notify hwmon events

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Message-ID: <41ceafa3-53b7-4229-58eb-3a8c331c3199@roeck-us.net>
Date:   Tue, 14 Feb 2023 06:54:52 -0800
From:   Guenter Roeck <linux@...ck-us.net>
To:     Naresh Solanki <naresh.solanki@...ements.com>
Cc:     Jean Delvare <jdelvare@...e.com>, linux-hwmon@...r.kernel.org,
        Patrick Rudolph <patrick.rudolph@...ements.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 4/4] hwmon: (pmbus/core): Notify hwmon events

On 2/14/23 06:11, Naresh Solanki wrote:
> Hi,
> 
> On 11-02-2023 09:16 pm, Guenter Roeck wrote:
>> On Tue, Feb 07, 2023 at 01:02:41PM +0100, Naresh Solanki wrote:
>>> From: Patrick Rudolph <patrick.rudolph@...ements.com>
>>>
>>> Notify hwmon events using the pmbus irq handler.
>>>
>>> Signed-off-by: Patrick Rudolph <patrick.rudolph@...ements.com>
>>> Signed-off-by: Naresh Solanki <Naresh.Solanki@...ements.com>
>>> ...
>>> Changes in V2
>>> - Remove __maybe_unsed attribute as its not needed.
>>> ---
>>>   drivers/hwmon/pmbus/pmbus_core.c | 48 ++++++++++++++++++++++++++++----
>>>   1 file changed, 43 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/drivers/hwmon/pmbus/pmbus_core.c b/drivers/hwmon/pmbus/pmbus_core.c
>>> index d5403baad60a..f6778a9c7126 100644
>>> --- a/drivers/hwmon/pmbus/pmbus_core.c
>>> +++ b/drivers/hwmon/pmbus/pmbus_core.c
>>> @@ -2735,8 +2735,36 @@ static const struct pmbus_status_category __maybe_unused pmbus_status_flag_map[]
>>>       },
>>>   };
>>> +#define to_dev_attr(_dev_attr) \
>>> +    container_of(_dev_attr, struct device_attribute, attr)
>>> +
>>> +static void pmbus_notify(struct pmbus_data *data, int page, int reg, int flags)
>>> +{
>>> +    int i;
>>> +
>>> +    for (i = 0; i < data->num_attributes; i++) {
>>> +        struct device_attribute *da = to_dev_attr(data->group.attrs[i]);
>>> +        struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
>>> +        int index = attr->index;
>>> +        u16 smask = pb_index_to_mask(index);
>>> +        u8 spage = pb_index_to_page(index);
>>> +        u16 sreg = pb_index_to_reg(index);
>>> +
>>> +        if (reg == sreg && page == spage && (smask & flags)) {
>>> +            dev_dbg(data->dev, "sysfs notify: %s", da->attr.name);
>>> +            sysfs_notify(&data->dev->kobj, NULL, da->attr.name);
>>> +            kobject_uevent(&data->dev->kobj, KOBJ_CHANGE);
>>> +            flags &= ~smask;
>>> +        }
>>> +
>>> +        if (!flags)
>>> +            break;
>>> +    }
>>> +}
>>> +
>>> +static int pmbus_get_flags(struct pmbus_data *data, u8 page, unsigned int *flags,
>>> +               bool notify)
>>> -static int __maybe_unused pmbus_get_flags(struct pmbus_data *data, u8 page, unsigned int *flags)
>>>   {
>>>       int i, status, ret;
>>>       const struct pmbus_status_category *cat;
>>> @@ -2764,6 +2792,10 @@ static int __maybe_unused pmbus_get_flags(struct pmbus_data *data, u8 page, unsi
>>>               if (status & bit->pflag)
>>>                   *flags |= bit->rflag;
>>>           }
>>> +
>>> +        if (notify && status)
>>> +            pmbus_notify(data, page, cat->reg, status);
>>> +
>>>       }
>>>       /*
>>> @@ -2866,7 +2898,7 @@ static int pmbus_regulator_get_error_flags(struct regulator_dev *rdev, unsigned
>>>       struct i2c_client *client = to_i2c_client(dev->parent);
>>>       struct pmbus_data *data = i2c_get_clientdata(client);
>>> -    return pmbus_get_flags(data, rdev_get_id(rdev), flags);
>>> +    return pmbus_get_flags(data, rdev_get_id(rdev), flags, false);
>>>   }
>>>   static int pmbus_regulator_get_status(struct regulator_dev *rdev)
>>> @@ -3108,10 +3140,14 @@ static irqreturn_t pmbus_fault_handler(int irq, void *pdata)
>>>   {
>>>       struct pmbus_data *data = pdata;
>>>       struct i2c_client *client = to_i2c_client(data->dev);
>>> -    int i, status;
>>> +    int i, status, ret;
>>> -    mutex_lock(&data->update_lock);
>>>       for (i = 0; i < data->info->pages; i++) {
>>> +        ret = pmbus_get_flags(data, i, &status, true);
>>> +        if (ret)
>>> +            return ret;
>>> +
>>> +        mutex_lock(&data->update_lock);
>>
>> You should introduce a locked version of pmbus_get_flags() and call
>> that function, and keep the existing locking in place.
>>
> I'm not sure if you meant to have pmbus_get_flags that wont use lock?
> 


__pmbus_get_flags(...)
{
	/* no lock acquired here */
}

pmbus_get_flags(...)
{
	int ret;

	mutex_lock(&data->update_lock);
	ret = __pmbus_get_flags(...);
	mutex_unlock(&data->update_lock);
	return ret;
}

Then call __pmbus_get_flags() from above code.

Guenter

>>>           status = pmbus_read_status_word(client, i);
>>>           if (status < 0) {
>>>               mutex_unlock(&data->update_lock);
>>> @@ -3120,8 +3156,10 @@ static irqreturn_t pmbus_fault_handler(int irq, void *pdata)
>>>           if (status & ~(PB_STATUS_OFF | PB_STATUS_BUSY | PB_STATUS_POWER_GOOD_N))
>>>               pmbus_clear_fault_page(client, i);
>>> +
>>> +        mutex_unlock(&data->update_lock);
>>>       }
>>> -    mutex_unlock(&data->update_lock);
>>> +
>>
>> This would add a second empty line (not that it matters because the code
>> should not change the locking in the first place).
>>
> Will remove the new line
>>>       return IRQ_HANDLED;
>>>   }