Received-SPF: pass (google.com: domain of linux-kernel+bounces-210963-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.80.249 as permitted sender) client-ip=147.75.80.249;
Message-ID: <c99d8df2-84ce-4b26-941e-b8a1413b8156@linaro.org>
Date: Wed, 12 Jun 2024 08:12:44 +0200
Precedence: bulk
MIME-Version: 1.0
User-Agent: Mozilla Thunderbird
Subject: Re: [PATCH V2 2/2] leds: add mp3326 driver
To: "Yuxi (Yuxi) Wang" <Yuxi.Wang@monolithicpower.com>,
 "pavel@ucw.cz" <pavel@ucw.cz>, "lee@kernel.org" <lee@kernel.org>,
 "robh+dt@kernel.org" <robh+dt@kernel.org>,
 "krzysztof.kozlowski+dt@linaro.org" <krzysztof.kozlowski+dt@linaro.org>,
 "conor+dt@kernel.org" <conor+dt@kernel.org>,
 "wyx137120466@gmail.com" <wyx137120466@gmail.com>
Cc: "linux-leds@vger.kernel.org" <linux-leds@vger.kernel.org>,
 "devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
 "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>
References: <20240611083236.1609-1-Yuxi.Wang@monolithicpower.com>
 <20240611083236.1609-3-Yuxi.Wang@monolithicpower.com>
 <c510fd3f-a55a-4ac9-bbc1-d2392027724c@linaro.org>
 <SN4PR13MB53103D139D9F816E5F4930EAF6C02@SN4PR13MB5310.namprd13.prod.outlook.com>
From: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Content-Language: en-US
Autocrypt: addr=krzysztof.kozlowski@linaro.org; keydata=
 xsFNBFVDQq4BEAC6KeLOfFsAvFMBsrCrJ2bCalhPv5+KQF2PS2+iwZI8BpRZoV+Bd5kWvN79
 cFgcqTTuNHjAvxtUG8pQgGTHAObYs6xeYJtjUH0ZX6ndJ33FJYf5V3yXqqjcZ30FgHzJCFUu
 JMp7PSyMPzpUXfU12yfcRYVEMQrmplNZssmYhiTeVicuOOypWugZKVLGNm0IweVCaZ/DJDIH
 gNbpvVwjcKYrx85m9cBVEBUGaQP6AT7qlVCkrf50v8bofSIyVa2xmubbAwwFA1oxoOusjPIE
 J3iadrwpFvsZjF5uHAKS+7wHLoW9hVzOnLbX6ajk5Hf8Pb1m+VH/E8bPBNNYKkfTtypTDUCj
 NYcd27tjnXfG+SDs/EXNUAIRefCyvaRG7oRYF3Ec+2RgQDRnmmjCjoQNbFrJvJkFHlPeHaeS
 BosGY+XWKydnmsfY7SSnjAzLUGAFhLd/XDVpb1Een2XucPpKvt9ORF+48gy12FA5GduRLhQU
 vK4tU7ojoem/G23PcowM1CwPurC8sAVsQb9KmwTGh7rVz3ks3w/zfGBy3+WmLg++C2Wct6nM
 Pd8/6CBVjEWqD06/RjI2AnjIq5fSEH/BIfXXfC68nMp9BZoy3So4ZsbOlBmtAPvMYX6U8VwD
 TNeBxJu5Ex0Izf1NV9CzC3nNaFUYOY8KfN01X5SExAoVTr09ewARAQABzTRLcnp5c3p0b2Yg
 S296bG93c2tpIDxrcnp5c3p0b2Yua296bG93c2tpQGxpbmFyby5vcmc+wsGUBBMBCgA+FiEE
 m9B+DgxR+NWWd7dUG5NDfTtBYpsFAmI+BxMCGwMFCRRfreEFCwkIBwIGFQoJCAsCBBYCAwEC
 HgECF4AACgkQG5NDfTtBYptgbhAAjAGunRoOTduBeC7V6GGOQMYIT5n3OuDSzG1oZyM4kyvO
 XeodvvYv49/ng473E8ZFhXfrre+c1olbr1A8pnz9vKVQs9JGVa6wwr/6ddH7/yvcaCQnHRPK
 mnXyP2BViBlyDWQ71UC3N12YCoHE2cVmfrn4JeyK/gHCvcW3hUW4i5rMd5M5WZAeiJj3rvYh
 v8WMKDJOtZFXxwaYGbvFJNDdvdTHc2x2fGaWwmXMJn2xs1ZyFAeHQvrp49mS6PBQZzcx0XL5
 cU9ZjhzOZDn6Apv45/C/lUJvPc3lo/pr5cmlOvPq1AsP6/xRXsEFX/SdvdxJ8w9KtGaxdJuf
 rpzLQ8Ht+H0lY2On1duYhmro8WglOypHy+TusYrDEry2qDNlc/bApQKtd9uqyDZ+rx8bGxyY
 qBP6bvsQx5YACI4p8R0J43tSqWwJTP/R5oPRQW2O1Ye1DEcdeyzZfifrQz58aoZrVQq+innR
 aDwu8qDB5UgmMQ7cjDSeAQABdghq7pqrA4P8lkA7qTG+aw8Z21OoAyZdUNm8NWJoQy8m4nUP
 gmeeQPRc0vjp5JkYPgTqwf08cluqO6vQuYL2YmwVBIbO7cE7LNGkPDA3RYMu+zPY9UUi/ln5
 dcKuEStFZ5eqVyqVoZ9eu3RTCGIXAHe1NcfcMT9HT0DPp3+ieTxFx6RjY3kYTGLOwU0EVUNc
 NAEQAM2StBhJERQvgPcbCzjokShn0cRA4q2SvCOvOXD+0KapXMRFE+/PZeDyfv4dEKuCqeh0
 hihSHlaxTzg3TcqUu54w2xYskG8Fq5tg3gm4kh1Gvh1LijIXX99ABA8eHxOGmLPRIBkXHqJY
 oHtCvPc6sYKNM9xbp6I4yF56xVLmHGJ61KaWKf5KKWYgA9kfHufbja7qR0c6H79LIsiYqf92
 H1HNq1WlQpu/fh4/XAAaV1axHFt/dY/2kU05tLMj8GjeQDz1fHas7augL4argt4e+jum3Nwt
 yupodQBxncKAUbzwKcDrPqUFmfRbJ7ARw8491xQHZDsP82JRj4cOJX32sBg8nO2N5OsFJOcd
 5IE9v6qfllkZDAh1Rb1h6DFYq9dcdPAHl4zOj9EHq99/CpyccOh7SrtWDNFFknCmLpowhct9
 5ZnlavBrDbOV0W47gO33WkXMFI4il4y1+Bv89979rVYn8aBohEgET41SpyQz7fMkcaZU+ok/
 +HYjC/qfDxT7tjKXqBQEscVODaFicsUkjheOD4BfWEcVUqa+XdUEciwG/SgNyxBZepj41oVq
 FPSVE+Ni2tNrW/e16b8mgXNngHSnbsr6pAIXZH3qFW+4TKPMGZ2rZ6zITrMip+12jgw4mGjy
 5y06JZvA02rZT2k9aa7i9dUUFggaanI09jNGbRA/ABEBAAHCwXwEGAEKACYCGwwWIQSb0H4O
 DFH41ZZ3t1Qbk0N9O0FimwUCYDzvagUJFF+UtgAKCRAbk0N9O0Fim9JzD/0auoGtUu4mgnna
 oEEpQEOjgT7l9TVuO3Qa/SeH+E0m55y5Fjpp6ZToc481za3xAcxK/BtIX5Wn1mQ6+szfrJQ6
 59y2io437BeuWIRjQniSxHz1kgtFECiV30yHRgOoQlzUea7FgsnuWdstgfWi6LxstswEzxLZ
 Sj1EqpXYZE4uLjh6dW292sO+j4LEqPYr53hyV4I2LPmptPE9Rb9yCTAbSUlzgjiyyjuXhcwM
 qf3lzsm02y7Ooq+ERVKiJzlvLd9tSe4jRx6Z6LMXhB21fa5DGs/tHAcUF35hSJrvMJzPT/+u
 /oVmYDFZkbLlqs2XpWaVCo2jv8+iHxZZ9FL7F6AHFzqEFdqGnJQqmEApiRqH6b4jRBOgJ+cY
 qc+rJggwMQcJL9F+oDm3wX47nr6jIsEB5ZftdybIzpMZ5V9v45lUwmdnMrSzZVgC4jRGXzsU
 EViBQt2CopXtHtYfPAO5nAkIvKSNp3jmGxZw4aTc5xoAZBLo0OV+Ezo71pg3AYvq0a3/oGRG
 KQ06ztUMRrj8eVtpImjsWCd0bDWRaaR4vqhCHvAG9iWXZu4qh3ipie2Y0oSJygcZT7H3UZxq
 fyYKiqEmRuqsvv6dcbblD8ZLkz1EVZL6djImH5zc5x8qpVxlA0A0i23v5QvN00m6G9NFF0Le
 D2GYIS41Kv4Isx2dEFh+/Q==
In-Reply-To: <SN4PR13MB53103D139D9F816E5F4930EAF6C02@SN4PR13MB5310.namprd13.prod.outlook.com>
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 7bit

On 12/06/2024 04:23, Yuxi (Yuxi) Wang wrote:
>>
>>> +/*
>>> + * PWM in the range of [0 255]
>>> + */
>>> +static int led_pwm_store(struct device *dev, struct device_attribute *attr,
>>> +			     const char *buf, size_t count)
>>
>> Nope.
> Hi Krzysztof,
> 
> What do you mean this Nope?
> Is it  format or function?

As sorry, you are reimplementing kernel interfaces, so that's a no.
> 
>>
>> ...
>>
>>> +	}
>>> +	r_val = r_val * 255 / 4095 + (r_val * 255 % 4095) / (4095 / 2);
>>> +	g_val = g_val * 255 / 4095 + (g_val * 255 % 4095) / (4095 / 2);
>>> +	b_val = b_val * 255 / 4095 + (b_val * 255 % 4095) / (4095 / 2);
>>> +	if (led->num_colors == 1)
>>> +		return sysfs_emit(buf, "0x%x\n", r_val);
>>> +	else
>>> +		return sysfs_emit(buf, "0x%x 0x%x 0x%x\n", r_val, g_val, b_val);
>>> +}
>>> +
>>> +static int led_enable_store(struct device *dev,
>>> +				struct device_attribute *attr, const char *buf,
>>> +				size_t count)
>>
>> Eeeee? store to enable LED? Really?
> Yes. The users need this function and we provide it.

NAK, I don't care about your users. You re-implemented existing ABI.
Without any ABI docs that's just pure duplication.

> 
> 
>>
>> ...
>>
>>> +{
>>> +	struct led_classdev *lcdev = dev_get_drvdata(dev);
>>> +	struct mp3326_led *led = container_of(lcdev, struct mp3326_led, cdev);
>>> +	struct mp3326 *chip = led->private_data;
>>> +	int ret;
>>> +	uint val, i;
>>
>>
>>> +
>>> +static DEVICE_ATTR_RW(led_pwm);
>>> +static DEVICE_ATTR_RW(led_enable);
>>> +static DEVICE_ATTR_RO(led_short_fault);
>>> +static DEVICE_ATTR_RO(led_open_fault);
>>
>> No, for multiple reasons:
>> 1. Where ABI documentation?
>> 2. There is a standard sysfs interface. No need for most of that. Please
>> explain why standard interface does not fit your needs - for each new
>> interface.
> Hi krzysztof,
> 
> 1. Where ABI documentation?
> A: 
> Sorry, the abi is insufficient.

Which one is insufficient?

> 
> Can I add it as comment above the function?
> 
> 2. There is a standard sysfs interface. No need for most of that. Please
> explain why standard interface does not fit your needs - for each new
>  interface.
> A:
> Leds has two ways to light dim. One is analog dimming, another pwm dimming.
> They are different in practice. 
> 
> In RGB module, pwm dimming can control color and analog dimming can control intensity.
> 
> Mp3326 supports the two ways which can operate contemporary.
> 
> In practice, I have needs below.
> 1. Operate rgb color and intensity.
> 2. enable/disable some channel
> 3. short/open fault notice.
> 
> However, The standard interface only has three functions below, they are not fit my needs.
> 1. multi_index
> 2. multi_intensity(only can dim using one way, so I use it as analog dimming)
> 3. led_mc_calc_color
> 

Please point to which ABI is not sufficient.

> 
> In order to fit my needs, I add the interface below.
> led_pwm       
> led_enable

Because especially this one sounds like you are mocking us.

> led_short_fault
> led_open_fault
> 


Best regards,
Krzysztof