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SubjectRe: [PATCH] pwm: rockchip: simplify rockchip_pwm_get_state()
Hello David,

On Thu, Sep 19, 2019 at 01:11:15PM +0200, oUwe Kleine-König wrote:
> On Thu, Sep 19, 2019 at 11:17:27AM +0200, Rasmus Villemoes wrote:
> > The way state->enabled is computed is rather convoluted and hard to
> > read - both branches of the if() actually do the exact same thing. So
> > remove the if(), and further simplify "<boolean condition> ? true :
> > false" to "<boolean condition>".
> >
> > Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
> > ---
> > I stumbled on this while trying to understand how the pwm subsystem
> > works. This patch is a semantic no-op, but it's also possible that,
> > say, the first branch simply contains a "double negative" so either
> > the != should be == or the "false : true" should be "true : false".
>
> The change looks obviously right, it's a noop.
>
> I share your doubts however. The construct was introduced in commit
> 831b2790507b ("pwm: rockchip: Use same PWM ops for each IP") by David
> Wu.
>
> Before there were rockchip_pwm_get_state_v1 for the supports_polarity =
> false case and rockchip_pwm_get_state_v2 for supports_polarity = true.
>
> In both state->enabled was assigned true if ((val & enable_conf) ==
> enable_conf). So I assume everything is fine.
>
> A confirmation by David would be great though.

This is still open. Can you please have a look at
https://patchwork.ozlabs.org/project/linux-pwm/patch/20190919091728.24756-1-linux@rasmusvillemoes.dk/
and verify it's correct?

Best regards
Uwe

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

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