Received-SPF: pass (google.com: domain of linux-kernel+bounces-154725-linux.lists.archive=gmail.com@vger.kernel.org designates 147.75.80.249 as permitted sender) client-ip=147.75.80.249;
Message-ID: <d549cf2b-a7fa-4644-8fcb-3c420503ee01@amperemail.onmicrosoft.com>
Date: Tue, 23 Apr 2024 15:45:12 +0700
User-Agent: Mozilla Thunderbird
Subject: Re: [PATCH v2 3/3] dt-bindings: hwmon: max31790: Add
 maxim,pwmout-pin-as-tach-input property
From: Chanh Nguyen <chanh@amperemail.onmicrosoft.com>
To: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>,
 Chanh Nguyen <chanh@os.amperecomputing.com>, Jean Delvare
 <jdelvare@suse.com>, Guenter Roeck <linux@roeck-us.net>,
 Rob Herring <robh+dt@kernel.org>,
 Krzysztof Kozlowski <krzysztof.kozlowski+dt@linaro.org>,
 Conor Dooley <conor+dt@kernel.org>, Justin Ledford
 <justinledford@google.com>, devicetree@vger.kernel.org,
 linux-hwmon@vger.kernel.org, linux-kernel@vger.kernel.org,
 OpenBMC Maillist <openbmc@lists.ozlabs.org>,
 Open Source Submission <patches@amperecomputing.com>
Cc: Phong Vo <phong@os.amperecomputing.com>,
 Thang Nguyen <thang@os.amperecomputing.com>,
 Quan Nguyen <quan@os.amperecomputing.com>
References: <20240414042246.8681-1-chanh@os.amperecomputing.com>
 <20240414042246.8681-4-chanh@os.amperecomputing.com>
 <13b195e6-cbbd-4f74-a6fa-d874cb4aaa45@linaro.org>
 <065243cc-09cf-4087-8842-bd4394fb324f@amperemail.onmicrosoft.com>
Content-Language: en-US
In-Reply-To: <065243cc-09cf-4087-8842-bd4394fb324f@amperemail.onmicrosoft.com>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 8bit
Precedence: bulk
MIME-Version: 1.0
X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1
X-MS-Exchange-AntiSpam-MessageData-0:
	=?utf-8?B?a1JQekFDeUpXbVFWcUw4U1Q0K2I3RzV2cDk3ekhCOVNYWVF6MDlCTktrUVVX?=
 =?utf-8?B?b0UrVW5ZR2ttSXpwRWlNTGZoYTg3TUU5WDVVRWxHck43S2RocWhmazFuODQx?=
 =?utf-8?B?bmQ0Vlh5WWpjQzd4ZlkrNWkySDlBNjlCeEQ1SVZXczRUTWx1WUo4YWZQVm1l?=
 =?utf-8?B?aG1Rb3dUTmhJL0NGSlhDdEJPdjlsR3NBdk81aUtIZ212MThZanh4MnhseEdN?=
 =?utf-8?B?MGx1eFdiYUx2aXl6OWsyV20zbURST01DbFQ0UnhlZ0RuTlBRSjk3TU9YV2RP?=
 =?utf-8?B?OUZtayszSjltVnh2OUpyanlMR3A3RUtFWXQxQURPNEFFVEVTcHJsT2RrVWhM?=
 =?utf-8?B?TEIyTTdRcGhQcE5iRDgrRnBoZkhlRHBOQ2xkbmR4TUJtUTdvaEp6VkRXWUxa?=
 =?utf-8?B?V25SZVlXam9lMHdxME5HOEFpakFydXIxZnRCVHVvdkg4UFFWVkd0ckZmNDI5?=
 =?utf-8?B?M2tSWFN1LzVVNUhMRUVsRUpVa29GRTAxdjhWMVpRRnVqbFJuZXByZ0ozc0dE?=
 =?utf-8?B?V01XWmNWSXhNNDl2WWRUY1hzWmxscS9aWG9rSWpXT0Q4ajE2ejBsU2srQTdB?=
 =?utf-8?B?Uno3czhzTTdHbk9OZ1pidDk4bHhBaUlGWWoxQjJLUDg3WTlsZDJqTXFSeGFN?=
 =?utf-8?B?NFlMUFNPcVlYcjFJcTRKeWVEUWRiZ0RoVFJVdTR4NHhaaVlkdndIMlBscmxK?=
 =?utf-8?B?R3FMSzgzOHBaM3htZlRCa1ROSno2b1A3WCs5UmJpWTFCQXhmU1FsbVJiZkl4?=
 =?utf-8?B?cFhSTHpxRjY4T0xHZDZXRzdIN1ZxcXRBdmhhcUZreWx4dEFPL1N3cVQzMnlU?=
 =?utf-8?B?eTNVd2l3NXF0Q1JEZ2NwNExLQ1p4TzF2MU9wd0J1N0wvSkZXZjlMWk1xV0ZL?=
 =?utf-8?B?Vkt2L1NpakJzSGNkWVR5U2FUWXFESlIra29ORkpEc3N6dmphRkduL1dMdldr?=
 =?utf-8?B?U1EvRk9hZS9ZL1hobTNzNUZvb0ZjelhHcFFyQXpuVDBQeW1pMFV0b0FpTERw?=
 =?utf-8?B?SEgrK2hmR2xuTUwvcmZnOVZDTDRLOU54cHlLZ0h2ZTNhSUp4eG5vUUZBalhr?=
 =?utf-8?B?Wk5uU0R6dkx3SUc0dlB0OW5FdFJacmw3NzlmVkZQUms3WUVpYlk2YUxUZEFk?=
 =?utf-8?B?a0dNS1JNNGNMQng1aENSUzFNTTdYR1FUUmlXTEdvdmRCV3JLVGVoV1FDQkFn?=
 =?utf-8?B?NXNDR0ZzOTFmaGltbVFXSFJvYWwwSkl1R1pKMWJuYUU1MnArL3FKTy93bHor?=
 =?utf-8?B?RFBLakgycmVTME1ZNXNGRGpTUDVTZXNCNjF6VXVZejdsaDF5cy9SaHF6VlJD?=
 =?utf-8?B?enBGNkg5VEx1MnZUbWJjVDdTVzloMmVtRUV4RkY1RzU2TWNhd0ppeHBaR1kz?=
 =?utf-8?B?d3FKVElkTlBNbFVhTThGSnY4d1g4Y21INFdvbGFaeFMvWm5iNDJ0aHdKNzZx?=
 =?utf-8?B?c1pGaFpzNmczTmU1T05UY1NZREVsYlVXbUJKYVJ6ejRpT1lZcjV0NUI3ZUZM?=
 =?utf-8?B?d0FtbEJndldvWjN4MWpoRUVuU1ZoMTFnYS9MOHdGNnMzLy94YWhqTWxxSE9E?=
 =?utf-8?B?RzRlcy9iVHE0eGdxekVjRUJDODJnSVFsalNIOVhPSVlreVh0L0FVa2NxQjJn?=
 =?utf-8?B?VEYrQzcxeERDeDNvcEFuVUYrODR0YWdHdmNzV1N2WjVnY3I3QUVhbG5UazFK?=
 =?utf-8?B?eHcyQ3BpbmlraERnZFdTb1RWbmYwM3ozYWJSNnNQM0ljNDhJVVlablZScHFF?=
 =?utf-8?B?WThaeDMzSGoyMUVtNzQzN3ArVnVJVWhUSFRSTDM5STFLbFVqVlV1elVXRTd2?=
 =?utf-8?B?a2NLUk9CSlQvSDdudjhFT0xnNVBRVHdWZld0VEdYNWM1TWs1NTE2QkRucSti?=
 =?utf-8?B?eHJHVXRCM2pmOEZIa0FZWE92OUJHQmNaaG44Y2VuUUorOWY2Zi80Sk1ESjJS?=
 =?utf-8?B?NGptSjRhY1c3VnNKUVNHSjlTMG9UWWlOYmtqQ2RuUVNlT2t5Z1dYSXZQNVR0?=
 =?utf-8?B?bFFWckYwTDRoUnprS1g5aFpCUnlzaldXb2RSMXpoOG9ld0ZiNENzVDNHWXZi?=
 =?utf-8?B?VktLdkpWemk5YytKcVNBL0JSMHU5SXR5WFp2WnVieFFUL0czNFYyQmF3MUV5?=
 =?utf-8?B?MmNpMWNjQ3B2b1JST20weG92QU5rM3pDZjgxQ3RjZjNzVDVMUXJSN3o3RC8y?=
 =?utf-8?Q?bEoGDkCJDXSiqjTe+0Sej3I=3D?=
X-OriginatorOrg: amperemail.onmicrosoft.com
X-MS-Exchange-CrossTenant-Network-Message-Id: 9917c390-700f-4fa6-ce80-08dc6371b74b
X-MS-Exchange-CrossTenant-AuthSource: DM6PR01MB5947.prod.exchangelabs.com
X-MS-Exchange-CrossTenant-AuthAs: Internal
X-MS-Exchange-CrossTenant-OriginalArrivalTime: 23 Apr 2024 08:45:24.3817
 (UTC)
X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted
X-MS-Exchange-CrossTenant-Id: 3bc2b170-fd94-476d-b0ce-4229bdc904a7
X-MS-Exchange-CrossTenant-MailboxType: HOSTED
X-MS-Exchange-CrossTenant-UserPrincipalName: OS2OddWgDnOcGFp6DaRhHxsG+TCrfdztLGVtMJU+Sz6Y19wgbdtrOB+ah05vKT2zY8EXIp7+F5bjhwyNysVy4HagfeyaOAxWe8lCnjZJPqY1fub5R9Xwr7okhpd94R1f
X-MS-Exchange-Transport-CrossTenantHeadersStamped: CH3PR01MB8267


On 16/04/2024 11:52, Chanh Nguyen wrote:
> 
> 
> On 14/04/2024 13:07, Krzysztof Kozlowski wrote:
>> On 14/04/2024 06:22, Chanh Nguyen wrote:
>>> The max31790 supports six pins, which are dedicated PWM outputs. Any 
>>> of the
>>> six PWM outputs can also be configured to serve as tachometer inputs,
>>> allowing for up to 12 tachometer fans to be monitored.
>>>
>>> Add a new vendor-specific property, 'maxim,pwmout-pin-as-tach-input',
>>> to allow PWMOUT to become a TACH input.
>>>
>>> An array of six integers responds to six PWM channels for configuring
>>> the PWM to TACH mode. When set to 0, the associated PWMOUT produces
>>> a PWM waveform for control of fan speed. When set to 1, PWMOUT becomes
>>> a TACH input.
>>>
>>> Signed-off-by: Chanh Nguyen <chanh@os.amperecomputing.com>
>>> ---
>>> Changes in v2:
>>>   - Update the vendor property name to 
>>> "maxim,pwmout-pin-as-tach-input"   [Rob]
>>>   - Update commit 
>>> message                                                 [Krzysztof]
>>
>> Please put binding before its user.
>>
> 
> Hi Krzysztof, I'll drop this [Path 3/3] in the patch series v3.
> 
> My patch series will only be two patches. They are "dt-bindings: hwmon: 
> Add maxim max31790" and "hwmon: (max31790): Support config PWM output 
> becomes TACH"
> 
>>> ---
>>>   .../devicetree/bindings/hwmon/maxim,max31790.yaml     | 11 +++++++++++
>>>   1 file changed, 11 insertions(+)
>>>
>>> diff --git 
>>> a/Documentation/devicetree/bindings/hwmon/maxim,max31790.yaml 
>>> b/Documentation/devicetree/bindings/hwmon/maxim,max31790.yaml
>>> index a561e5a3e9e4..2d4f50bc7c41 100644
>>> --- a/Documentation/devicetree/bindings/hwmon/maxim,max31790.yaml
>>> +++ b/Documentation/devicetree/bindings/hwmon/maxim,max31790.yaml
>>> @@ -30,6 +30,16 @@ properties:
>>>     resets:
>>>       maxItems: 1
>>> +  maxim,pwmout-pin-as-tach-input:
>>> +    description: |
>>> +      An array of six integers responds to six PWM channels for
>>> +      configuring the pwm to tach mode.
>>> +      When set to 0, the associated PWMOUT produces a PWM waveform for
>>> +      control of fan speed. When set to 1, PWMOUT becomes a TACH input
>>> +    $ref: /schemas/types.yaml#/definitions/uint8-array
>>> +    maxItems: 6
>>> +    minItems: 6
>>
>> tach-ch solves your case. You define which inputs should be used for 
>> tach.
>>
> 
> Agree Krzysztof. I'll use the tach-ch property from the fan-common.yaml 
> to solve my case. So I will not need to define a new vendor property as 
> "maxim,pwmout-pin-as-tach-input". I'll drop this [Path 3/3] in the patch 
> series v3.
> 
> 
>> Best regards,
>> Krzysztof
>>


Hi Krzysztof,

I checked in the
Documentation/devicetree/bindings/hwmon/fan-common.yaml. I found the
tach-ch property, but it seems define the tach channel used for fan.

      tach-ch:
      	description:
        		The tach channel used for the fan.
      	$ref: /schemas/types.yaml#/definitions/uint8-array


In my purpose, I would like to configure the pwm output pins to become 
tachometer input pins by setting bit[0] in the Configuration Register.


I think a vendor property is suitable for this purpose. It is only 
available on specific MAX31790 fan controllers and not on other fan 
controller devices. So I think we can't use the "tach-ch" in 
fan-common.yaml.

I discussed it in the thread
https://lore.kernel.org/lkml/ce8b2b49-b194-42f7-8f83-fcbf7b460970@amperemail.onmicrosoft.com/ 
, but I have not yet received Rob's response.

Please share your comment with me. I hope that will help us make a final 
decision.

Thank Krzysztof very much!