linux-kernel - Re: [PATCH v5 1/1] hwmon: Add driver for Astera Labs PT5161L retimer

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Date: Tue, 6 Feb 2024 08:33:43 +0100
From: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To: Guenter Roeck <linux@...ck-us.net>
Cc: Cosmo Chou <chou.cosmo@...il.com>, robh+dt@...nel.org,
 krzysztof.kozlowski+dt@...aro.org, conor+dt@...nel.org, jdelvare@...e.com,
 corbet@....net, broonie@...nel.org, naresh.solanki@...ements.com,
 vincent@...emblay.dev, patrick.rudolph@...ements.com,
 luca.ceresoli@...tlin.com, bhelgaas@...gle.com, festevam@...x.de,
 alexander.stein@...tq-group.com, heiko@...ech.de, jernej.skrabec@...il.com,
 macromorgan@...mail.com, forbidden405@...mail.com, sre@...nel.org,
 linus.walleij@...aro.org, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-hwmon@...r.kernel.org,
 linux-doc@...r.kernel.org, cosmo.chou@...ntatw.com
Subject: Re: [PATCH v5 1/1] hwmon: Add driver for Astera Labs PT5161L retimer

On 05/02/2024 17:15, Guenter Roeck wrote:
> On Mon, Feb 05, 2024 at 04:26:08PM +0100, Krzysztof Kozlowski wrote:
>> On 05/02/2024 16:20, Cosmo Chou wrote:
>>> This driver implements support for temperature monitoring of Astera Labs
>>> PT5161L series PCIe retimer chips.
>>>
>>> This driver implementation originates from the CSDK available at
>>> Link: https://github.com/facebook/openbmc/tree/helium/common/recipes-lib/retimer-v2.14
>>> The communication protocol utilized is based on the I2C/SMBus standard.
>>>
>>> Signed-off-by: Cosmo Chou <chou.cosmo@...il.com>
>>> ---
> [ ... ]
> 
>>> +
>>> +static int __init pt5161l_init(void)
>>> +{
>>> +	pt5161l_debugfs_dir = debugfs_create_dir("pt5161l", NULL);
>>
>> Drivers don't need initcalls. For sure any debugfs should not be handled
>> here but in probe.
>>
> 
> Lots of hwmon drivers have init functions, for basic chip detection of
> Super-I/O chips (example: drivers/hwmon/nct6775-platform.c) and to create
> a parent debugfs subdirectory for the driver. The probe function then adds
> subdirecties per chip instantiation. Example for pmbus, in
> drivers/hwmon/pmbus/pmbus_core.c:

Core bus components are a bit different...

> 
> static int __init pmbus_core_init(void)
> {
>         pmbus_debugfs_dir = debugfs_create_dir("pmbus", NULL);
>         if (IS_ERR(pmbus_debugfs_dir))
>                 pmbus_debugfs_dir = NULL;
> 
>         return 0;
> }
> 
> static void __exit pmbus_core_exit(void)
> {
>         debugfs_remove_recursive(pmbus_debugfs_dir);
> }
> 
> Are you saying this is all wrong ? What alternative would you suggest ?

Just create parent directory in probe and only keep remove in __exit.
But you are right that might not be much better approach.

Best regards,
Krzysztof