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([2600:1700:e321:62f0:da43:aeff:fecc:bfd5]) by smtp.gmail.com with ESMTPSA id d2e1a72fcca58-739da0b2d76sm10881998b3a.122.2025.04.08.11.07.48 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 08 Apr 2025 11:07:49 -0700 (PDT) Sender: Guenter Roeck Message-ID: <661f972b-cd0f-4d9c-b429-5990edf8f13f@roeck-us.net> Date: Tue, 8 Apr 2025 11:07:48 -0700 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] hwmon: (ina2xx) make regulator 'vs' support optional To: Ciprian Marian Costea Cc: Jean Delvare , linux-hwmon@vger.kernel.org, linux-kernel@vger.kernel.org, NXP S32 Linux , imx@lists.linux.dev, Christophe Lizzi , Alberto Ruiz , Enric Balletbo , Eric Chanudet , Florin Buica References: <20250403101516.3047802-1-ciprianmarian.costea@oss.nxp.com> <4efff19d-b5e6-49b5-9a15-e4af622c6ebf@oss.nxp.com> <2a12e6be-c253-4542-86a0-aacb71671ed6@roeck-us.net> <1d7318bf-9971-41aa-a952-85367f001c9c@oss.nxp.com> Content-Language: en-US From: Guenter Roeck Autocrypt: addr=linux@roeck-us.net; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 4/4/25 01:36, Ciprian Marian Costea wrote: > On 4/3/2025 7:06 PM, Guenter Roeck wrote: >> On Thu, Apr 03, 2025 at 05:29:26PM +0300, Ciprian Marian Costea wrote: >>> On 4/3/2025 3:15 PM, Guenter Roeck wrote: >>>> On 4/3/25 03:15, Ciprian Costea wrote: >>>>> From: Ciprian Marian Costea >>>>> >>>>> S32G2/S32G3 based boards which integrate the ina231 sensor do not have a >>>>> dedicated voltage regulator. >>>>> >>>>> Co-developed-by: Florin Buica >>>>> Signed-off-by: Florin Buica >>>>> Signed-off-by: Ciprian Marian Costea >>>>> --- >>>>>    drivers/hwmon/ina2xx.c | 4 ++-- >>>>>    1 file changed, 2 insertions(+), 2 deletions(-) >>>>> >>>>> diff --git a/drivers/hwmon/ina2xx.c b/drivers/hwmon/ina2xx.c >>>>> index 345fe7db9de9..ab4972f94a8c 100644 >>>>> --- a/drivers/hwmon/ina2xx.c >>>>> +++ b/drivers/hwmon/ina2xx.c >>>>> @@ -959,8 +959,8 @@ static int ina2xx_probe(struct i2c_client *client) >>>>>            return PTR_ERR(data->regmap); >>>>>        } >>>>> -    ret = (dev, "vs"); >>>>> -    if (ret) >>>>> +    ret = devm_regulator_get_enable_optional(dev, "vs"); >>>> >>>> devm_regulator_get_enable() should provide a dummy regulator if there is >>>> no explicit regulator. Why does this not work ? >>>> >>>>> +    if (ret < 0 && ret != -ENODEV) >>>> >>>> Why this added check ? >>>> >>>> I know it used to be necessary if regulator support is disabled, >>>> but that is no longer the case. >>>> >>>> Guenter >>>> >>> >>> Hello Guenter, >>> >>> I've just tested and devm_regulator_get_enable() does work as you've >>> described, providing a dummy regulator. >>> >>> But, according to the 'ti,ina2xx' binding [1] I see that the `vs-supply` >>> property is not required. Hence wouldn't it be correct for `vs-supply` to be >>> optional ? Using 'devm_regulator_get_enable_optional()' >>> >> Yes, but the reasoning you provided is different and suggested that the >> current code would not work. Since that is not the case, the change would >> be purely cosmetic. Also, I still don't see why the -ENODEV check would be >> necessary. >> >> Guenter > > For boards such as S32G274A-EVB, S32G274A-RDB2 and S32G399A-RDB3 which do not have a voltage regulator, 'devm_regulator_get_enable_optional()' would return error value -19 (-ENODEV). Also, other usages from the Linux Kernel seem to perform the same error check when using 'devm_regulator_get_enable_optional()' [1], [2] and [3]. > > This patch would help in S32G2 and S32G3 to not print an unnecessary kernel log warning hinting usage of a dummy regulator when such a regulator is not required according to the binding. > > Would you like me to send a V2 with the commit title updated as follows ? > > " > hwmon: (ina2xx) make regulator 'vs' support optional > > According to the 'ti,ina2xx' binding, the 'vs-supply' property is optional. Furthermore, S32G2/S32G3 based boards which integrate the ina231 sensor do not have a dedicated voltage regulator. Thus, making regulator support optional would help in avoiding any unnecessary kernel log warnings during boot. > " Make it: "According to the 'ti,ina2xx' binding, the 'vs-supply' property is optional. Use devm_regulator_get_enable_optional() to avoid a kernel warning message if the property is not provided. " Then add a note to the code explaining that the check for -ENODEV is necessary because the regulator core returns -ENODEV if the regulator is not available. Why it makes sense for this function to return -ENODEV if an _optional_ regulator is not available escapes me, but that is a different issue. Guenter