Hi Uwe,
Thanks for the feedback.
> Subject: Re: [PATCH v6 2/2] pwm: Add support for RZ/G2L GPT
>
> Hello,
>
> On Wed, Sep 21, 2022 at 01:46:54PM +0000, Biju Das wrote:
> > > Actually it's worse:
> > >
> > > - When both channels are used, setting the duty-cycle on one
> aborts the
> > > currently running period on the other and starts it anew.
> > >
> > > (Did I get this correctly?)
> >
> > I think, I have fixed that issue with the below logic Which allows
> to
> > update duty cycle on the fly.
> >
> > Now the only limitation is w.r.to disabling channels as we need to
> > disable together as stopping the counter affects both.
> >
> > /*
> > * Counter must be stopped before modifying mode, prescaler,
> timer
> > * counter and buffer enable registers. These registers are
> shared
> > * between both channels. So allow updating these registers only
> for the
> > * first enabled channel.
> > */
> > if (rzg2l_gpt->user_count <= 1)
> > rzg2l_gpt_disable(rzg2l_gpt);
> >
> > is_counter_running = rzg2l_gpt_read(rzg2l_gpt, RZG2L_GTCR) &
> RZG2L_GTCR_CST;
> > if (!is_counter_running)
> > /* GPT set operating mode (saw-wave up-counting) */
> > rzg2l_gpt_modify(rzg2l_gpt, RZG2L_GTCR, RZG2L_GTCR_MD,
> > RZG2L_GTCR_MD_SAW_WAVE_PWM_MODE);
>
> So if the PWM is already running (e.g. from the bootloader) and the
> mode is wrong, this isn't fixed? Similar problems in the if blocks
> below.
This is taken care by the above code. It stops the counter for first enabled channel in Linux
and then changes the mode as per Linux.
<snippet>
if (rzg2l_gpt->user_count <= 1)
rzg2l_gpt_disable(rzg2l_gpt);
</snippet>
Cheers,
Biju
>
> > /* Set count direction */
> > rzg2l_gpt_write(rzg2l_gpt, RZG2L_GTUDDTYC, RZG2L_UP_COUNTING);
> >
> > if (!is_counter_running)
> > /* Select count clock */
> > rzg2l_gpt_modify(rzg2l_gpt, RZG2L_GTCR, RZG2L_GTCR_TPCS,
> > FIELD_PREP(RZG2L_GTCR_TPCS, prescale));
> >
> > /* Set period */
> > rzg2l_gpt_write(rzg2l_gpt, RZG2L_GTPR, pv);
> >
> > /* Set duty cycle */
> > rzg2l_gpt_write(rzg2l_gpt, RZG2L_GTCCR(pwm->hwpwm), dc);
> >
> > if (!is_counter_running) {
> > /* Set initial value for counter */
> > rzg2l_gpt_write(rzg2l_gpt, RZG2L_GTCNT, 0);
> >
> > /* Set no buffer operation */
> > rzg2l_gpt_write(rzg2l_gpt, RZG2L_GTBER, 0);
> > }
>
> Best regards
> Uwe
>
> --
> Pengutronix e.K. | Uwe Kleine-König
> |
> Industrial Linux Solutions |
> https://www.pengutronix.de/ |
