linux-kernel - Re: [PATCH 2/6] pwm: add mule pwm-over-i2c driver

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Message-ID: <33d93798-459b-4d33-ac59-623a68ea48cf@cherry.de>
Date: Wed, 17 Jul 2024 10:48:52 +0200
From: Quentin Schulz <quentin.schulz@...rry.de>
To: Uwe Kleine-König <u.kleine-koenig@...libre.com>
Cc: Farouk Bouabid <farouk.bouabid@...rry.de>, Rob Herring <robh@...nel.org>,
 Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley
 <conor+dt@...nel.org>, Heiko Stuebner <heiko@...ech.de>,
 linux-pwm@...r.kernel.org, devicetree@...r.kernel.org,
 linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
 linux-rockchip@...ts.infradead.org
Subject: Re: [PATCH 2/6] pwm: add mule pwm-over-i2c driver

Hi Uwe,

On 7/15/24 5:09 PM, Uwe Kleine-König wrote:
> Hello Quentin,
> 
> On Mon, Jul 15, 2024 at 02:16:15PM +0200, Quentin Schulz wrote:

[...]

>> To give a bit more info on this, there are two possible flavors of the MCU,
>> ATtiny 816 (datasheet: https://ww1.microchip.com/downloads/en/DeviceDoc/ATtiny416-816-DataSheet-DS40001913B.pdf)
>> and STM32F072CB (datasheet: https://www.st.com/content/ccc/resource/technical/document/reference_manual/c2/f8/8a/f2/18/e6/43/96/DM00031936.pdf/files/DM00031936.pdf/jcr:content/translations/en.DM00031936.pdf).
>>
>> FYI, on ATtiny, we use TCA in single-slope PWM generation mode and PERBUF
>> and CMP2BUF as period and duty-cycle registers. On STM32, we use TIM15 in
>> PWM mode and ARR and CCR1 as period and duty-cycle registers.
> 
> Wouldn't it be more natural with these to have duty in a base-2 register
> for duty, in the assumption that your MCUs habe this, too?
> 

Not sure to understand what you meant by base-2 register here? I am 
guessing you rather wanted to suggest a different unit/representation of 
the duty cycle in the register in the FW API?

Cheers,
Quentin