linux-kernel - Re: [PATCH] of: Make of_node_name

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Date:   Thu, 24 Jan 2019 18:06:54 -0800
From:   Frank Rowand <frowand.list@...il.com>
To:     Florian Fainelli <f.fainelli@...il.com>,
        linux-kernel@...r.kernel.org
Cc:     vivien.didelot@...il.com, Rob Herring <robh+dt@...nel.org>,
        "open list:OPEN FIRMWARE AND FLATTENED DEVICE TREE" 
        <devicetree@...r.kernel.org>, Frank Rowand <frowand.list@...il.com>
Subject: Re: [PATCH] of: Make of_node_name_eq() case insensitive

On 1/24/19 5:20 PM, Florian Fainelli wrote:
> 
> 
> On 1/24/19 3:45 PM, Frank Rowand wrote:
>> On 1/24/19 12:08 PM, Florian Fainelli wrote:
>>> Since c32569e358ad ("regulator: Use of_node_name_eq for node name
>>> comparisons") Vivien reported the mc13892-regulator complaining about
>>> not being able to find regulators.
>>>
>>> This is because prior to that commit we used of_node_cmp() to compare
>>> the regulator array passed from mc13892_regulators down to
>>> mc13xxx_parse_regulators_dt() and they are all defined in uppercase
>>> letters by the MC13892_*_DEFINE* macros, whereas they are defined as
>>> lowercase in the DTS.
>>>
>>> Fix this by use strncasecmp() since that makes sure the comparison is
>>> case insensitive like what of_node_cmp() did.
>>>
>>> Reported-by: Vivien Didelot <vivien.didelot@...il.com>
>>> Fixes: c32569e358ad ("regulator: Use of_node_name_eq for node name comparisons")
>>> Signed-off-by: Florian Fainelli <f.fainelli@...il.com>
>>> ---
>>>  drivers/of/base.c | 3 ++-
>>>  1 file changed, 2 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/drivers/of/base.c b/drivers/of/base.c
>>> index 5226e898476e..ff47c86277cb 100644
>>> --- a/drivers/of/base.c
>>> +++ b/drivers/of/base.c
>>> @@ -66,7 +66,8 @@ bool of_node_name_eq(const struct device_node *np, const char *name)
>>>  	node_name = kbasename(np->full_name);
>>>  	len = strchrnul(node_name, '@') - node_name;
>>>  
>>> -	return (strlen(name) == len) && (strncmp(node_name, name, len) == 0);
>>> +	return (strlen(name) == len) &&
>>> +		(strncasecmp(node_name, name, len) == 0);
>>>  }
>>>  EXPORT_SYMBOL(of_node_name_eq);
>>>  
>>>
>>
>> Node names are case sensitive.  Please fix mc13xxx_parse_regulators_dt() to
>> properly handle case instead of changing of_node_name_eq().
> 
> Fair enough, should we issue a warning if np->full_name contains upper
> case while name does not (and vice versa) to help troubleshoot cases
> like the one we found with Vivien?

It seems like a lot of work to detect that specific case.  If anything,
maybe just add some text to the existing "Unknown regulator: ..." warning
in mc13xxx_parse_regulators_dt() to mention that case matters.

-Frank