Re: [PATCH 15/16] backlight: remove pandora_bl

[Andreas Kemnade <andreas@kemnade.info>]

On Mon, 10 Aug 2026 12:45:16 +0200
"H. Nikolaus Schaller" <hns@goldelico.com> wrote:

> Hi Daniel,
> 
> > Am 10.08.2026 um 12:35 schrieb Daniel Thompson <danielt@kernel.org>:
> > 
> > On Sat, Jul 11, 2026 at 08:02:02AM +0200, H. Nikolaus Schaller wrote:  
> >> Retire the platform specific pandora backlight driver since
> >> it can now be replaced by twl_pm and device tree.
> >> 
> >> Signed-off-by: H. Nikolaus Schaller <hns@goldelico.com>  
> > 
> > Yay!
> > 
> > Reviewed-by: Daniel Thompson (RISCstar) <danielt@kernel.org>  
> 
> Well, there were some good comments by Sahiko to the prerequisites of this patch,
> because it has one speciality the PWM BL driver does not handle (avoid
> interpretation of PWM signals as W1 protocol).
> 
> I haven't found time to work on this, so we can't remove this yet.
> 
> In the end it may either remain a pandora_bl driver (converted to DT)
> or become a patch for something else.
> 
But then it is a TPS61161 on top of PWM, not a pandora driver.
And then there might be just a quirk for that chip in the pwm_bl using
triggered by a compatible. I guess the quirk is this:


if (priv->old_state == PANDORABL_WAS_OFF) {
-		/*
-		 * set PWM duty cycle to max. TPS61161 seems to use this
-		 * to calibrate it's PWM sensitivity when it starts.
-		 */
-		twl_i2c_write_u8(TWL_MODULE_PWM, MAX_VALUE, TWL_PWM0_OFF);
-
-		/* first enable clock, then PWM0 out */
-		twl_i2c_read_u8(TWL4030_MODULE_INTBR, &r, TWL_INTBR_GPBR1);
-		r &= ~PWM0_ENABLE;
-		r |= PWM0_CLK_ENABLE;
-		twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_GPBR1);
-		r |= PWM0_ENABLE;
-		twl_i2c_write_u8(TWL4030_MODULE_INTBR, r, TWL_INTBR_GPBR1);
-
-		/*
-		 * TI made it very easy to enable digital control, so easy that
-		 * it often triggers unintentionally and disabes PWM control,
-		 * so wait until 1 wire mode detection window ends.
-		 */
-		usleep_range(2000, 10000);
-	}

Regards,
Andreas