6.5-stable review patch. If anyone has any objections, please let me know.
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From: Artur Weber aweber.kernel@gmail.com
[ Upstream commit 4c09e20b3c85f60353ace21092e34f35f5e3ab00 ]
As pointed out by Uwe Kleine-König[1], the changes introduced in commit c1ff7da03e16 ("video: backlight: lp855x: Get PWM for PWM mode during probe") caused the PWM state set up by the bootloader to be re-set when the driver is probed. This differs from the behavior from before that patch, where the PWM state would be initialized on the first brightness change.
Fix this by moving the PWM state initialization into the PWM control function. Add a new variable, needs_pwm_init, to the device info struct to allow us to check whether we need the initialization, or whether it has already been done.
[1] https://lore.kernel.org/lkml/20230614083953.e4kkweddjz7wztby@pengutronix.de/
Fixes: c1ff7da03e16 ("video: backlight: lp855x: Get PWM for PWM mode during probe") Signed-off-by: Artur Weber aweber.kernel@gmail.com Reviewed-by: Daniel Thompson daniel.thompson@linaro.org Link: https://lore.kernel.org/r/20230714121440.7717-2-aweber.kernel@gmail.com Signed-off-by: Lee Jones lee@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/video/backlight/lp855x_bl.c | 20 ++++++++++++-------- 1 file changed, 12 insertions(+), 8 deletions(-)
diff --git a/drivers/video/backlight/lp855x_bl.c b/drivers/video/backlight/lp855x_bl.c index 1c9e921bca14a..349ec324bc1ea 100644 --- a/drivers/video/backlight/lp855x_bl.c +++ b/drivers/video/backlight/lp855x_bl.c @@ -71,6 +71,7 @@ struct lp855x { struct device *dev; struct lp855x_platform_data *pdata; struct pwm_device *pwm; + bool needs_pwm_init; struct regulator *supply; /* regulator for VDD input */ struct regulator *enable; /* regulator for EN/VDDIO input */ }; @@ -220,7 +221,15 @@ static void lp855x_pwm_ctrl(struct lp855x *lp, int br, int max_br) { struct pwm_state state;
- pwm_get_state(lp->pwm, &state); + if (lp->needs_pwm_init) { + pwm_init_state(lp->pwm, &state); + /* Legacy platform data compatibility */ + if (lp->pdata->period_ns > 0) + state.period = lp->pdata->period_ns; + lp->needs_pwm_init = false; + } else { + pwm_get_state(lp->pwm, &state); + }
state.duty_cycle = div_u64(br * state.period, max_br); state.enabled = state.duty_cycle; @@ -387,7 +396,6 @@ static int lp855x_probe(struct i2c_client *cl) const struct i2c_device_id *id = i2c_client_get_device_id(cl); const struct acpi_device_id *acpi_id = NULL; struct device *dev = &cl->dev; - struct pwm_state pwmstate; struct lp855x *lp; int ret;
@@ -470,15 +478,11 @@ static int lp855x_probe(struct i2c_client *cl) else return dev_err_probe(dev, ret, "getting PWM\n");
+ lp->needs_pwm_init = false; lp->mode = REGISTER_BASED; dev_dbg(dev, "mode: register based\n"); } else { - pwm_init_state(lp->pwm, &pwmstate); - /* Legacy platform data compatibility */ - if (lp->pdata->period_ns > 0) - pwmstate.period = lp->pdata->period_ns; - pwm_apply_state(lp->pwm, &pwmstate); - + lp->needs_pwm_init = true; lp->mode = PWM_BASED; dev_dbg(dev, "mode: PWM based\n"); }