parker-int64

Thanks for the great work Nick. I recently bought a SPI screen and managed to drive it with panel-mipi-dbi in the newer kernel (apparently this module didn't exist in Radxa's official image with kernel 5.15). The panel was a ST7789V 240*320 TFT LCD and I have a A7Z, with the `Radxa-cubie-A7a-a7z-v0.6.4` server image installed. And I have put the work on [Github](https://github.com/parker-int64/sun60i-a733-dtoverlays). During the experiment, I discovered that the PWM (used for display backlight) in the allwinner BSP seems to have a bug. The Allwinner Sunxi PWM driver may incorrectly reverts the PWM pin to GPIO input immediately after switching the pinctrl state. Thus I can control the PWM with the file nodes but can't attached it to related pins. For example, I'm using the `sun60i-a733-pwm1-7.dtso` overlay, which is supposed to enable the PJ25. After enabling the overlay, I noticed that the PWM nodes were created and I can controll these nodes. But the pinctrl suggest that it was unclamied: $ cat /sys/kernel/debug/pinctrl/2000000.pinctrl/pinmux- pins | grep PJ25 pin 313 (PJ25): UNCLAIMED Later on, AI found out that the `devm_pinctrl_put(pctl);` in bsp/drivers/pwm/pwm-sunxi.c may have been incorrectly called on the clean stage of the `sunxi_pwm_pin_set_state`: 520 static int sunxi_pwm_pin_set_state(struct device *dev, char *name) 521 { 522 struct pinctrl *pctl; 523 struct pinctrl_state *state = NULL; 524 int err; 525 526 pctl = devm_pinctrl_get(dev); 527 if (IS_ERR(pctl)) { 528 sunxi_err(dev, "pinctrl_get failed\n"); 529 err = PTR_ERR(pctl); 530 return err; 531 } 532 533 state = pinctrl_lookup_state(pctl, name); 534 if (IS_ERR(state)) { 535 sunxi_err(dev, "pinctrl_lookup_state(%s) failed\n", name); 536 err = PTR_ERR(state); 537 goto exit; 538 } 539 540 err = pinctrl_select_state(pctl, state); 541 if (err) { 542 sunxi_err(dev, "pinctrl_select_state(%s) failed\n", name); 543 goto exit; 544 } 545 546 exit: 547 /* 548 * devm_pinctrl_put() releases the last pinctrl reference, 549 * causing pinmux_disable_setting() to restore the pin to 550 * its default GPIO function. The devres framework will 551 * release this resource automatically when the device is 552 * destroyed. 553 */ 554 devm_pinctrl_put(pctl); 555 return err; 556 557 } Also it gives me a workaround `sunxi-pwm-child-pinctrl.c`, introduces an additional pinctrl reference, preventing `devm_pinctrl_put()` from reducing the reference count to zero. Both the patch file and the workaround source is available on Github. However I only tried the workaround since I have some trouble compile the full kernel at the moment, will try some time later and update more details on Github. And at last the pwm-backlight worked as expected and my LCD light up.