linux-kernel - Re: [PATCH v1] pwm: lpss: wait_for

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Message-ID: <ZsQunMKglYdUwzqo@black.fi.intel.com>
Date: Tue, 20 Aug 2024 08:50:20 +0300
From: Raag Jadav <raag.jadav@...el.com>
To: Andy Shevchenko <andriy.shevchenko@...ux.intel.com>
Cc: ukleinek@...nel.org, mika.westerberg@...ux.intel.com,
	jarkko.nikula@...ux.intel.com, linux-pwm@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v1] pwm: lpss: wait_for_update() before configuring pwm

On Mon, Aug 19, 2024 at 11:21:51AM +0300, Andy Shevchenko wrote:
> On Mon, Aug 19, 2024 at 01:34:12PM +0530, Raag Jadav wrote:
> > Wait for SW_UPDATE bit to clear before configuring pwm channel instead of
> 
> PWM
> 
> > failing right away, which will reduce failure rates on early access.
> 
> So, what is the problem this patch solves (or is trying to solve)?

Less failures with less code, so just a minor improvement.

> Second, there are two important behavioural changes:
> - error code change (it's visible to user space);

This function is already used in this path just a few lines below.

> - an additional, quite a long by the way, timeout.
> 
> Second one does worry me a lot as it might add these 0.5s to the boot time
> or so per PWM in question.

On the contrary, having a working set of PWMs would be a relatively
rewarding experience IMHO.

Raag