linux-kernel - Re: [PATCH 0/1] pwm: meson: fix scheduling while atomic issue

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Date:   Mon, 25 Mar 2019 09:50:37 +0100
From:   Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>
To:     Martin Blumenstingl <martin.blumenstingl@...glemail.com>
Cc:     thierry.reding@...il.com, narmstrong@...libre.com,
        jbrunet@...libre.com, linux-pwm@...r.kernel.org,
        linux-amlogic@...ts.infradead.org,
        linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/1] pwm: meson: fix scheduling while atomic issue

Hello,

On Mon, Mar 25, 2019 at 09:41:53AM +0100, Uwe Kleine-König wrote:
> If you want to implement further cleanups, my questions and propositions
> are:
> 
>  - Is there a publicly available manual for this hardware? If yes, you
>    can add a link to it in the header of the driver.
> 
>  - Why do you handle reparenting of the PWM's clk in .request? Wouldn't
>    this be more suitable in .apply?
> 
>  - Does stopping the PWM (i.e. clearing MISC_{A,B}_EN in the MISC_AB
>    register) freeze the output, or is the currently running period
>    completed first? (The latter is the right behaviour.)
> 
>  - Please point out in the header that for changing period/duty
>    cycle/polarity the hardware must be stopped. (I suggest to apply the
>    style used in https://www.spinics.net/lists/linux-pwm/msg09262.html
>    for some consistency.)

Another thing I just noted: The .get_state callback only sets .enabled
but nothing of the remaining information is provided.

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-König            |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |