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    SubjectRe: [PATCH v4 2/2] pwm: visconti: Add Toshiba Visconti SoC PWM support
    Hi Uwe,

    On Sat, Apr 17, 2021 at 05:50:09PM +0200, Uwe Kleine-König wrote:
    > Hello Nobuhiro,
    >
    > On Fri, Apr 16, 2021 at 09:15:23PM +0900, Nobuhiro Iwamatsu wrote:
    > > > > > For me the critical (and only) difference between "off" and
    > > > > > "duty cycle = 0" is that when a new configuration is to be applied. In
    > > > > > the "off" state a new period can (and should) start immediately, while
    > > > > > with "duty_cycle = 0" the rising edge should be delayed until the
    > > > > > currently running period is over.[1]
    > > > > >
    > > > > > So the thing to do here (IMHO) is:
    > > > > >
    > > > > > Iff with PIPGM_PCSR = 0 configuring a new setting (that is finalized
    > > > > > with writing a non-zero value to PIPGM_PCSR) completes the currently
    > > > > > running period, then always assume the PWM as enabled.
    > > > >
    > > > > Yes, this device works that way.
    > > >
    > > > OK, then please use
    > > >
    > > > state->enabled = true
    > > >
    > > > unconditionally in visconti_pwm_get_state().
    > >
    > > Please let me check.
    > > If I unconditionally add 'state->enabled = true' to visconti_pwm_get_state(),
    > > state->enabled is set to true because visconti_pwm_get_state() is called when
    > > the device is created (this is when I write the device number to the export of
    > > /sys/class/pwm/pwmchip0 ).
    > > And since PIPGM_PCSR is 0 in this state, the pulse by PWM is not output.
    >
    > A PWM that is currently configured with .enabled = true and .duty_cycle
    > = 0 doesn't have a pulse, so this is fine.
    >

    I understood, thanks.

    > > However, I think this means that the device is working as this driver.
    >
    > I don't understand this sentence.

    The description of the struct pwm_state says "PWM enabled status".
    I thought 'state-> enabled' would hold the working state of the hardware.

    >
    > Best regards
    > Uwe

    Best regards,
    Nobuhiro

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