linux-kernel - Re: [PATCH 2/2] hwmon: (pmbus) add MFR

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Message-ID: <1b12cb3a-3d87-8254-b229-dcf83ad0bc0a@roeck-us.net>
Date:   Wed, 20 Apr 2022 09:06:25 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     wujek dev <dev_public@...ek.eu>
Cc:     Jean Delvare <jdelvare@...e.com>, linux-hwmon@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] hwmon: (pmbus) add MFR_* registers to debugfs

On 4/20/22 08:51, wujek dev wrote:
> ------- Original Message -------
> On Wednesday, April 20th, 2022 at 16:15, Guenter Roeck <linux@...ck-us.net> wrote:
> 
> 
>>
>>
>> On 4/20/22 06:58, wujek dev wrote:
>>
>>> ------- Original Message -------
>>> On Wednesday, April 20th, 2022 at 15:53, Guenter Roeck linux@...ck-us.net wrote:
>>>
>>>> On 4/20/22 05:22, Adam Wujek wrote:
>>>>
>>>>> Add registers to debugfs:
>>>>> PMBUS_MFR_ID
>>>>> PMBUS_MFR_MODEL
>>>>> PMBUS_MFR_REVISION
>>>>> PMBUS_MFR_LOCATION
>>>>> PMBUS_MFR_DATE
>>>>> PMBUS_MFR_SERIAL
>>>>>
>>>>> Signed-off-by: Adam Wujek dev_public@...ek.eu
>>>>
>>>> Where is patch 1/2, and why did you resend this patch ?
>>>
>>> There should be no "1/2" since this and the second patch are unrelated.
>>> I resend it because I rebased it on master.
>>
>> Please provide change logs and version your patches in the future.
> ok, thank you for your patience.
>>
>>> Adam
>>>
>>>> Guenter
>>>>
>>>>> ---
>>>>> drivers/hwmon/pmbus/pmbus_core.c | 84 ++++++++++++++++++++++++++++++++
>>>>> 1 file changed, 84 insertions(+)
>>>>>
>>>>> diff --git a/drivers/hwmon/pmbus/pmbus_core.c b/drivers/hwmon/pmbus/pmbus_core.c
>>>>> index 0af7a3d74f47..1dc186780ccf 100644
>>>>> --- a/drivers/hwmon/pmbus/pmbus_core.c
>>>>> +++ b/drivers/hwmon/pmbus/pmbus_core.c
>>>>> @@ -2625,6 +2625,30 @@ static int pmbus_debugfs_get_status(void *data, u64 *val)
>>>>> DEFINE_DEBUGFS_ATTRIBUTE(pmbus_debugfs_ops_status, pmbus_debugfs_get_status,
>>>>> NULL, "0x%04llx\n");
>>>>>
>>>>> +static ssize_t pmbus_debugfs_mfr_read(struct file *file, char __user *buf,
>>>>> + size_t count, loff_t *ppos)
>>>>> +{
>>>>> + int rc;
>>>>> + struct pmbus_debugfs_entry *entry = file->private_data;
>>>>> + char data[I2C_SMBUS_BLOCK_MAX + 2] = { 0 };
>>>>> +
>>>>> + rc = i2c_smbus_read_block_data(entry->client, entry->reg, data);
>>>>> + if (rc < 0)
>>>>> + return rc;
>>>>> +
>>>>> + data[rc] = '\n';
>>>>> + rc += 2;
>>
>>
>> Why +2 ?
>>
> Copied from another driver.
> +1 due to '\n'
> +1 due to NULL character (smbus block transfer does not include it in the length)
> Explanation included in v3 patch.

"copied from another driver" is not really a good argument.
That other driver might just be buggy.

What do you see in userspace when you read the data ? A string that ends with
"\n\0" ? If so, does the "\0" at the end add any value ?

Guenter