linux-kernel - Re: [PATCH v1] hwmon: Add driver for MPS MPQ8785 Synchronous Step-Down Converter

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Message-ID: <cc561e9a-e493-43dd-ac9b-cf14786130ff@roeck-us.net>
Date: Sun, 28 Jan 2024 09:13:12 -0800
From: Guenter Roeck <linux@...ck-us.net>
To: Charles Hsu <ythsu0511@...il.com>
Cc: jdelvare@...e.com, corbet@....net, Delphine_CC_Chiu@...ynn.com,
 linux-hwmon@...r.kernel.org, linux-doc@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-i2c@...r.kernel.org,
 Charles.Hsu@...ntatw.com
Subject: Re: [PATCH v1] hwmon: Add driver for MPS MPQ8785 Synchronous
 Step-Down Converter

On 1/27/24 16:00, Guenter Roeck wrote:
> On Fri, Jan 26, 2024 at 03:52:13PM +0800, Charles Hsu wrote:
>> Add support for mpq8785 device from Monolithic Power Systems, Inc.
>> (MPS) vendor. This is synchronous step-down controller.
>>
> 
> "(MPS) vendor" above has no value.
> 
> I find no reference that this chip actually exists. Sorry, but I can not
> apply such patches without confirmation that the chip actually exists.
> 

I since learned that the chip does exist, so this is no longer a concern.

>> Signed-off-by: Charles Hsu <ythsu0511@...il.com>
>> ---
>> Change in v1:
>>      Initial patchset.
> 
> A change log or v1 tag is not needed for the first version of a patch
> or patch series.
> 
>> ---
> ...
>> +		PMBUS_HAVE_VIN | PMBUS_HAVE_VOUT | PMBUS_HAVE_TEMP | PMBUS_HAVE_IOUT |
>> +		PMBUS_HAVE_STATUS_INPUT | PMBUS_HAVE_STATUS_TEMP,
> 
> I am not too happy that all those drivers claim to have no output status
> registers. It always makes me wonder if the definitions are just copied
> from one driver to the next.

I also learned that the chip supports additional status registers. Please
list all supported status registers.

I also learned that the chips voltage output mode is configurable. As such,

+	.format[PSC_CURRENT_OUT] = direct,

won't do because it cause instantiation to fail due to mode mismatch
in pmbus_identify_common() if the mode is configured to linear or vid mode.
This will need to be addressed.

Thanks,
Guenter