linux-kernel - Re: [PATCH v9 0/3] Add support for Allwinner PWM on D1/T113s/R329 SoCs

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Date: Thu, 23 May 2024 14:30:32 +0900
From: きくちゃんさん <kikuchan98@...il.com>
To: John Watts <contact@...kia.org>
Cc: privatesub2@...il.com, aou@...s.berkeley.edu, bigunclemax@...il.com, 
	conor+dt@...nel.org, devicetree@...r.kernel.org, fusibrandon13@...il.com, 
	jernej.skrabec@...il.com, krzk+dt@...nel.org, 
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org, 
	linux-pwm@...r.kernel.org, linux-riscv@...ts.infradead.org, 
	linux-sunxi@...ts.linux.dev, mkl@...gutronix.de, p.zabel@...gutronix.de, 
	palmer@...belt.com, paul.walmsley@...ive.com, robh@...nel.org, 
	samuel@...lland.org, ukleinek@...nel.org, wens@...e.org
Subject: Re: [PATCH v9 0/3] Add support for Allwinner PWM on D1/T113s/R329 SoCs

Hello John,

Your method is quite impressive and challenging.

I think PWM is not only for LCD backlighting, but also for signal generation.
For instance, imagine an application software that sends a stream to
one PWM channel to synthesize sound by changing its period (plays a
square wave).
By your method, if the other PWM channel is used for LCD backlighting,
it may flicker repeatedly on DIV_M changes.
(Or simply both channels for streo sound synthesize, you may hear lots
of pop noise)

It means the setting of one channel can affect the other, which users
may not anticipate.

Best regards,
kikuchan.