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- Fix-ups
- Improve bootloader/kernel device handover - Bug Fixes - Stabilise backlight -----BEGIN PGP SIGNATURE----- iQIzBAABCgAdFiEEdrbJNaO+IJqU8IdIUa+KL4f8d2EFAmE3brsACgkQUa+KL4f8 d2Fpvg//WqnzzpoAhhJpsqOvThvptAFinlVH9ql7gsivCBXsY8Fu0RsynlEy3E4o DZzhBT/gE1UPkv2HbntuCikZdza1vcyIZrYkUnGb9yAokd0apX2Iss6K50Z7H3U1 Bvot6MgG9VdgbPD3gcIPO/SEyODl6YhDByUU7kWDgmmi2IM/chcd1+SMK0GtAgfb NYcgLPi5nZ8j2zhfhA19H9tdr01Kz0dhBEjfVxDfC2l9bhAl1E7Uj96Ugz9b5oSk /J5yhogfFhNuK0kfw1bQ0IUNpDxtg9hh8Q8uk45AX+6w9XyQ3/hkoNhTWbiEpawz IZaFI7mTBYmtdwJkcbZ3dP5n4zYSzXloayCHRfbwqUfn6n62EwhGgKOpEkSjbgMD 825WWjvjUctgjJSOJuWcJftJvf8s+xViycwSP4sbssbCC22QT019dcpsAaHS471Z wJJoOxYAMylVIFfG2NOZGkDpVdlYfTGef1RoBrrwWibZPcUOQYi6UNBxxJNlzxHN B3xE6r19M91ER9y7qKJ7TD2v5P3hfyFaweetoMaYe6HilEQBj9iaQfvsnqlx/4EC qiyf5N72NTm+gUU2gOKoZHkTUILizP89t2blkzrcbwTFnKR1WHHHinJ3nkVguXmB 17sywI3qaJJb4KaMlRzist9qIDxjbrUjDXC7cMYNXqyEfS6aRXo= =wi80 -----END PGP SIGNATURE----- Merge tag 'backlight-next-5.15' of git://git.kernel.org/pub/scm/linux/kernel/git/lee/backlight Pull backlight updates from Lee Jones: "Fix-ups: - Improve bootloader/kernel device handover Bug Fixes: - Stabilise backlight in ktd253 driver" * tag 'backlight-next-5.15' of git://git.kernel.org/pub/scm/linux/kernel/git/lee/backlight: backlight: pwm_bl: Improve bootloader/kernel device handover backlight: ktd253: Stabilize backlight
This commit is contained in:
commit
2d7b4cdbb5
2 changed files with 83 additions and 46 deletions
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@ -25,6 +25,7 @@
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#define KTD253_T_LOW_NS (200 + 10) /* Additional 10ns as safety factor */
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#define KTD253_T_HIGH_NS (200 + 10) /* Additional 10ns as safety factor */
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#define KTD253_T_OFF_CRIT_NS 100000 /* 100 us, now it doesn't look good */
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#define KTD253_T_OFF_MS 3
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struct ktd253_backlight {
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@ -34,13 +35,50 @@ struct ktd253_backlight {
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u16 ratio;
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};
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static void ktd253_backlight_set_max_ratio(struct ktd253_backlight *ktd253)
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{
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gpiod_set_value_cansleep(ktd253->gpiod, 1);
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ndelay(KTD253_T_HIGH_NS);
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/* We always fall back to this when we power on */
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}
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static int ktd253_backlight_stepdown(struct ktd253_backlight *ktd253)
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{
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/*
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* These GPIO operations absolutely can NOT sleep so no _cansleep
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* suffixes, and no using GPIO expanders on slow buses for this!
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*
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* The maximum number of cycles of the loop is 32 so the time taken
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* should nominally be:
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* (T_LOW_NS + T_HIGH_NS + loop_time) * 32
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*
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* Architectures do not always support ndelay() and we will get a few us
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* instead. If we get to a critical time limit an interrupt has likely
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* occured in the low part of the loop and we need to restart from the
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* top so we have the backlight in a known state.
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*/
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u64 ns;
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ns = ktime_get_ns();
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gpiod_set_value(ktd253->gpiod, 0);
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ndelay(KTD253_T_LOW_NS);
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gpiod_set_value(ktd253->gpiod, 1);
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ns = ktime_get_ns() - ns;
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if (ns >= KTD253_T_OFF_CRIT_NS) {
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dev_err(ktd253->dev, "PCM on backlight took too long (%llu ns)\n", ns);
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return -EAGAIN;
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}
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ndelay(KTD253_T_HIGH_NS);
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return 0;
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}
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static int ktd253_backlight_update_status(struct backlight_device *bl)
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{
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struct ktd253_backlight *ktd253 = bl_get_data(bl);
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int brightness = backlight_get_brightness(bl);
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u16 target_ratio;
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u16 current_ratio = ktd253->ratio;
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unsigned long flags;
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int ret;
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dev_dbg(ktd253->dev, "new brightness/ratio: %d/32\n", brightness);
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@ -62,37 +100,34 @@ static int ktd253_backlight_update_status(struct backlight_device *bl)
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}
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if (current_ratio == 0) {
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gpiod_set_value_cansleep(ktd253->gpiod, 1);
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ndelay(KTD253_T_HIGH_NS);
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/* We always fall back to this when we power on */
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ktd253_backlight_set_max_ratio(ktd253);
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current_ratio = KTD253_MAX_RATIO;
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}
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/*
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* WARNING:
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* The loop to set the correct current level is performed
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* with interrupts disabled as it is timing critical.
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* The maximum number of cycles of the loop is 32
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* so the time taken will be (T_LOW_NS + T_HIGH_NS + loop_time) * 32,
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*/
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local_irq_save(flags);
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while (current_ratio != target_ratio) {
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/*
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* These GPIO operations absolutely can NOT sleep so no
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* _cansleep suffixes, and no using GPIO expanders on
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* slow buses for this!
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*/
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gpiod_set_value(ktd253->gpiod, 0);
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ndelay(KTD253_T_LOW_NS);
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gpiod_set_value(ktd253->gpiod, 1);
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ndelay(KTD253_T_HIGH_NS);
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/* After 1/32 we loop back to 32/32 */
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if (current_ratio == KTD253_MIN_RATIO)
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ret = ktd253_backlight_stepdown(ktd253);
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if (ret == -EAGAIN) {
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/*
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* Something disturbed the backlight setting code when
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* running so we need to bring the PWM back to a known
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* state. This shouldn't happen too much.
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*/
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gpiod_set_value_cansleep(ktd253->gpiod, 0);
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msleep(KTD253_T_OFF_MS);
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ktd253_backlight_set_max_ratio(ktd253);
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current_ratio = KTD253_MAX_RATIO;
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else
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} else if (current_ratio == KTD253_MIN_RATIO) {
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/* After 1/32 we loop back to 32/32 */
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current_ratio = KTD253_MAX_RATIO;
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} else {
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current_ratio--;
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}
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}
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local_irq_restore(flags);
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ktd253->ratio = current_ratio;
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dev_dbg(ktd253->dev, "new ratio set to %d/32\n", target_ratio);
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@ -409,6 +409,33 @@ static bool pwm_backlight_is_linear(struct platform_pwm_backlight_data *data)
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static int pwm_backlight_initial_power_state(const struct pwm_bl_data *pb)
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{
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struct device_node *node = pb->dev->of_node;
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bool active = true;
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/*
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* If the enable GPIO is present, observable (either as input
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* or output) and off then the backlight is not currently active.
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* */
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if (pb->enable_gpio && gpiod_get_value_cansleep(pb->enable_gpio) == 0)
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active = false;
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if (!regulator_is_enabled(pb->power_supply))
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active = false;
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if (!pwm_is_enabled(pb->pwm))
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active = false;
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/*
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* Synchronize the enable_gpio with the observed state of the
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* hardware.
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*/
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if (pb->enable_gpio)
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gpiod_direction_output(pb->enable_gpio, active);
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/*
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* Do not change pb->enabled here! pb->enabled essentially
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* tells us if we own one of the regulator's use counts and
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* right now we do not.
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*/
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/* Not booted with device tree or no phandle link to the node */
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if (!node || !node->phandle)
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* assume that another driver will enable the backlight at the
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* appropriate time. Therefore, if it is disabled, keep it so.
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*/
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/* if the enable GPIO is disabled, do not enable the backlight */
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if (pb->enable_gpio && gpiod_get_value_cansleep(pb->enable_gpio) == 0)
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return FB_BLANK_POWERDOWN;
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/* The regulator is disabled, do not enable the backlight */
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if (!regulator_is_enabled(pb->power_supply))
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return FB_BLANK_POWERDOWN;
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/* The PWM is disabled, keep it like this */
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if (!pwm_is_enabled(pb->pwm))
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return FB_BLANK_POWERDOWN;
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return FB_BLANK_UNBLANK;
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return active ? FB_BLANK_UNBLANK: FB_BLANK_POWERDOWN;
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}
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static int pwm_backlight_probe(struct platform_device *pdev)
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@ -486,18 +500,6 @@ static int pwm_backlight_probe(struct platform_device *pdev)
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goto err_alloc;
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}
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/*
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* If the GPIO is not known to be already configured as output, that
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* is, if gpiod_get_direction returns either 1 or -EINVAL, change the
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* direction to output and set the GPIO as active.
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* Do not force the GPIO to active when it was already output as it
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* could cause backlight flickering or we would enable the backlight too
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* early. Leave the decision of the initial backlight state for later.
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*/
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if (pb->enable_gpio &&
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gpiod_get_direction(pb->enable_gpio) != 0)
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gpiod_direction_output(pb->enable_gpio, 1);
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pb->power_supply = devm_regulator_get(&pdev->dev, "power");
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if (IS_ERR(pb->power_supply)) {
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ret = PTR_ERR(pb->power_supply);
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