Hi Clemens,
On Mon, Apr 12, 2021 at 07:11:58PM +0200, Clemens Gruber wrote:
> On Mon, Apr 12, 2021 at 06:30:45PM +0200, Uwe Kleine-König wrote:
> > On Mon, Apr 12, 2021 at 03:27:43PM +0200, Clemens Gruber wrote:
> > > static unsigned int pca9685_pwm_get_duty(struct pca9685 *pca, int channel)
> > > {
> > > - unsigned int off_h = 0, val = 0;
> > > + struct pwm_device *pwm = &pca->chip.pwms[channel];
> > > + unsigned int off = 0, on = 0, val = 0;
> > >
> > > if (WARN_ON(channel >= PCA9685_MAXCHAN)) {
> > > /* HW does not support reading state of "all LEDs" channel */
> > > return 0;
> > > }
> > >
> > > - regmap_read(pca->regmap, LED_N_OFF_H(channel), &off_h);
> > > - if (off_h & LED_FULL) {
> > > + regmap_read(pca->regmap, LED_N_OFF_H(channel), &off);
> > > + if (off & LED_FULL) {
> > > /* Full OFF bit is set */
> > > return 0;
> > > }
> > >
> > > - regmap_read(pca->regmap, LED_N_ON_H(channel), &val);
> > > - if (val & LED_FULL) {
> > > + regmap_read(pca->regmap, LED_N_ON_H(channel), &on);
> > > + if (on & LED_FULL) {
> > > /* Full ON bit is set */
> > > return PCA9685_COUNTER_RANGE;
> > > }
> > >
> > > - val = 0;
> > > regmap_read(pca->regmap, LED_N_OFF_L(channel), &val);
> > > - return ((off_h & 0xf) << 8) | (val & 0xff);
> > > + off = ((off & 0xf) << 8) | (val & 0xff);
> > > + if (!pwm->args.usage_power)
> > > + return off;
> > > +
> > > + /* Read ON register to calculate duty cycle of staggered output */
> > > + val = 0;
> > > + regmap_read(pca->regmap, LED_N_ON_L(channel), &val);
> > > + on = ((on & 0xf) << 8) | (val & 0xff);
> > > + return (off - on) & (PCA9685_COUNTER_RANGE - 1);
> >
> > If LED_N_ON is != 0 but usage_power is false, the returned state is
> > bogus.
>
> If usage_power is false, LED_N_ON is guaranteed to be 0. It is reset to
> 0 in probe and never changed. Or did I miss something?
Ah right, so my concern is only a challenge once the reset in probe goes
away.
> > > }
> > >
> > > #if IS_ENABLED(CONFIG_GPIOLIB)
> > > @@ -439,9 +469,11 @@ static int pca9685_pwm_probe(struct i2c_client *client,
> > > reg &= ~(MODE1_ALLCALL | MODE1_SUB1 | MODE1_SUB2 | MODE1_SUB3);
> > > regmap_write(pca->regmap, PCA9685_MODE1, reg);
> > >
> > > - /* Reset OFF registers to POR default */
> > > + /* Reset OFF/ON registers to POR default */
> > > regmap_write(pca->regmap, PCA9685_ALL_LED_OFF_L, LED_FULL);
> > > regmap_write(pca->regmap, PCA9685_ALL_LED_OFF_H, LED_FULL);
> > > + regmap_write(pca->regmap, PCA9685_ALL_LED_ON_L, 0);
> > > + regmap_write(pca->regmap, PCA9685_ALL_LED_ON_H, 0);
> > >
> > > pca->chip.ops = &pca9685_pwm_ops;
> > > /* Add an extra channel for ALL_LED */
> > > @@ -450,6 +482,9 @@ static int pca9685_pwm_probe(struct i2c_client *client,
> > > pca->chip.dev = &client->dev;
> > > pca->chip.base = -1;
> > >
> > > + pca->chip.of_xlate = of_pwm_xlate_with_flags;
> > > + pca->chip.of_pwm_n_cells = 3;
> > > +
> >
> > Huh, you're incompatibly changing the device tree binding here.
>
> No, I don't think so:
>
> The third cell is optional with of_pwm_xlate_with_flags.
> So previous DTs with pwm-cells = <2> will still work.
I thought that .of_pwm_n_cells was enforced, let me check the code ... I
had in mind that of_pwm_get() enforced that, but I cannot find it, so I
guess you're right and my concern is unjustified.
Best regards
Uwe
--
Pengutronix e.K. | Uwe Kleine-König |
Industrial Linux Solutions | https://www.pengutronix.de/ |
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