linux-kernel - Re: [PATCH] Documentation: firmware: Clarify firmware path usage

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Date:   Mon, 10 Apr 2023 16:12:32 -0700
From:   Florian Fainelli <f.fainelli@...il.com>
To:     Jonathan Corbet <corbet@....net>, linux-kernel@...r.kernel.org
Cc:     gregkh@...uxfoundation.org,
        "open list:DOCUMENTATION" <linux-doc@...r.kernel.org>
Subject: Re: [PATCH] Documentation: firmware: Clarify firmware path usage



On 4/10/2023 3:43 PM, Jonathan Corbet wrote:
> Florian Fainelli <f.fainelli@...il.com> writes:
> 
>> Newline characters will be taken into account for the firmware search
>> path parameter, warn users about that and provide an example using 'echo
>> -n' such that it clarifies the typical use of that parameter.
>>
>> Signed-off-by: Florian Fainelli <f.fainelli@...il.com>
>> ---
>>   Documentation/driver-api/firmware/fw_search_path.rst | 9 +++++++--
>>   1 file changed, 7 insertions(+), 2 deletions(-)
>>
>> diff --git a/Documentation/driver-api/firmware/fw_search_path.rst b/Documentation/driver-api/firmware/fw_search_path.rst
>> index a360f1009fa3..d7cb1e8f0076 100644
>> --- a/Documentation/driver-api/firmware/fw_search_path.rst
>> +++ b/Documentation/driver-api/firmware/fw_search_path.rst
>> @@ -22,5 +22,10 @@ can use the file:
>>   
>>   * /sys/module/firmware_class/parameters/path
>>   
>> -You would echo into it your custom path and firmware requested will be
>> -searched for there first.
>> +You would echo into it your custom path and firmware requested will be searched
>> +for there first. Be aware that newline characters will be taken into account
>> +and may not produce the intended effects. For instance you might want to use:
>> +
>> +echo -n /path/to/script > /sys/module/firmware_class/parameters/path
>> +
>> +to ensure that your script is being used.
> 
> So I have no problem with applying this, but I have to ask...might it
> not be better to fix the implementation of that sysfs file to strip
> surrounding whitespace from the provided path?  This patch has the look
> of a lesson learned the hard way; rather than codifying this behavior
> into a feature, perhaps we could just make the next person's life a bit
> easier...?

I was not sure whether it was on purpose or not, Greg, will we break 
anyone's use case if we strip off \n from the firmware path passed via 
sysfs?
-- 
Florian