linux-kernel - Re: PWM regression causing failures with the pwm-atmel driver

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Date:   Tue, 20 Jun 2023 16:24:31 +0200
From:   Thorsten Leemhuis <regressions@...mhuis.info>
To:     Peter Rosin <peda@...ntia.se>, LKML <linux-kernel@...r.kernel.org>,
        Uwe Kleine-König <u.kleine-koenig@...gutronix.de>,
        linux-pwm@...r.kernel.org
Cc:     Thierry Reding <thierry.reding@...il.com>,
        Conor Dooley <conor.dooley@...rochip.com>,
        Claudiu Beznea <claudiu.beznea@...rochip.com>
Subject: Re: PWM regression causing failures with the pwm-atmel driver

On 22.05.23 17:19, Peter Rosin wrote:
>
> I have a device with a "sound card" that has an amplifier that needs
> an extra boost when high amplification is requested. This extra
> boost is controlled with a pwm-regulator.
> 
> As of commit c73a3107624d ("pwm: Handle .get_state() failures") this
> device no longer works. I have tracked the problem to an unfortunate
> interaction between the underlying PWM driver and the PWM core.
> [...]>
> Approach 1. will maybe clobber the saved pwm->state such that
> it no longer works to get the period/duty_cycle if/when the
> PWM is disabled? Maybe only for some corner case? But that might
> be a significant corner case?
> 
> Approach 2. will maybe mess up some unrelated functionality?
> 
> Approach 3. is ugly, intrusive and is in all likelihood
> incomplete. It also needs a rebase from the culprit commit.
> 
> #regzbot introduced c73a3107624d

What happened to this? There was quite a bit of discussion, but then
nothing happened anymore.

Ciao, Thorsten (wearing his 'the Linux kernel's regression tracker' hat)
--
Everything you wanna know about Linux kernel regression tracking:
https://linux-regtracking.leemhuis.info/about/#tldr
If I did something stupid, please tell me, as explained on that page.

#regzbot poke