From 86511719c369c1cc98f82f24ad137da03e7ea58e Mon Sep 17 00:00:00 2001 From: Timo Karjalainen Date: Thu, 2 Oct 2008 12:07:22 +0300 Subject: [PATCH] lm8323 pwm fixes This patch fixes two problems in LM8323 PWM control. One is that locking is needed when setting and reading pwm->desired_brightness asynchronously. The other is that LM8323 may stop a PWM script only after the current instruction has finished. If it is a long RAMP, the chip would keep executing the old instruction and new settings were effectively ignored. Signed-off-by: Timo Karjalainen Signed-off-by: Daniel Stone Signed-off-by: Tony Lindgren --- drivers/input/keyboard/lm8323.c | 129 +++++++++++++++++--------------- 1 file changed, 69 insertions(+), 60 deletions(-) diff --git a/drivers/input/keyboard/lm8323.c b/drivers/input/keyboard/lm8323.c index 72bb587eb03..342ef6a9290 100644 --- a/drivers/input/keyboard/lm8323.c +++ b/drivers/input/keyboard/lm8323.c @@ -141,6 +141,8 @@ struct lm8323_pwm { int fade_time; int brightness; int desired_brightness; + int running; + struct mutex lock; struct work_struct work; struct led_classdev cdev; }; @@ -384,6 +386,15 @@ static int lm8323_configure(struct lm8323_chip *lm) return 0; } +static void pwm_done(struct lm8323_pwm *pwm) +{ + mutex_lock(&pwm->lock); + pwm->running = 0; + if (pwm->desired_brightness != pwm->brightness) + schedule_work(&pwm->work); + mutex_unlock(&pwm->lock); +} + /* * Bottom half: handle the interrupt by posting key events, or dealing with * errors appropriately. @@ -411,12 +422,18 @@ static void lm8323_work(struct work_struct *work) "reinitialising\n"); lm8323_configure(lm); } - if (ints & INT_PWM1) + if (ints & INT_PWM1) { debug(&lm->client->dev, "pwm1 engine completed\n"); - if (ints & INT_PWM2) + pwm_done(&lm->pwm1); + } + if (ints & INT_PWM2) { debug(&lm->client->dev, "pwm2 engine completed\n"); - if (ints & INT_PWM3) + pwm_done(&lm->pwm2); + } + if (ints & INT_PWM3) { debug(&lm->client->dev, "pwm3 engine completed\n"); + pwm_done(&lm->pwm3); + } } mutex_unlock(&lm->lock); @@ -458,92 +475,80 @@ static void lm8323_write_pwm_one(struct lm8323_pwm *pwm, int pos, u16 cmd) /* * Write a script into a given PWM engine, concluding with PWM_END. - * If 'keepalive' is specified, the engine will be kept running - * indefinitely. + * If 'kill' is nonzero, the engine will be shut down at the end + * of the script, producing a zero output. Otherwise the engine + * will be kept running at the final PWM level indefinitely. */ -static void lm8323_write_pwm(struct lm8323_pwm *pwm, int keepalive, - int len, ...) +static void lm8323_write_pwm(struct lm8323_pwm *pwm, int kill, + int len, const u16 *cmds) { struct lm8323_chip *lm = pwm_to_lm8323(pwm); - int i, cmd; - va_list ap; - - /* - * If there are any scripts running at the moment, terminate them - * and make sure the duty cycle is as if it finished. - */ - lm8323_write(lm, 2, LM8323_CMD_STOP_PWM, pwm->id); - - va_start(ap, len); - for (i = 0; i < len; i++) { - cmd = va_arg(ap, int); - lm8323_write_pwm_one(pwm, i, cmd); - } - va_end(ap); + int i; - /* Wait for a trigger from any channel. This keeps the engine alive. */ - if (keepalive) - lm8323_write_pwm_one(pwm, i++, PWM_WAIT_TRIG(0xe)); - else - lm8323_write_pwm_one(pwm, i++, PWM_END(1)); + for (i = 0; i < len; i++) + lm8323_write_pwm_one(pwm, i, cmds[i]); + lm8323_write_pwm_one(pwm, i++, PWM_END(kill)); lm8323_write(lm, 2, LM8323_CMD_START_PWM, pwm->id); + pwm->running = 1; } static void lm8323_pwm_work(struct work_struct *work) { struct lm8323_pwm *pwm = work_to_pwm(work); - int div, perstep, steps, hz, direction, keepalive; + int div512, perstep, steps, hz, up, kill; + u16 pwm_cmds[3]; + int num_cmds = 0; + + mutex_lock(&pwm->lock); - /* Do nothing if we're already at the requested level. */ - if (pwm->desired_brightness == pwm->brightness) + /* + * Do nothing if we're already at the requested level, + * or previous setting is not yet complete. In the latter + * case we will be called again when the previous PWM script + * finishes. + */ + if (pwm->running || pwm->desired_brightness == pwm->brightness) { + mutex_unlock(&pwm->lock); return; + } - keepalive = (pwm->desired_brightness > 0); - direction = (pwm->desired_brightness > pwm->brightness); + kill = (pwm->desired_brightness == 0); + up = (pwm->desired_brightness > pwm->brightness); steps = abs(pwm->desired_brightness - pwm->brightness); /* * Convert time (in ms) into a divisor (512 or 16 on a refclk of * 32768Hz), and number of ticks per step. */ - if ((pwm->fade_time / steps) > (32768 / 512)) - div = 512; - else - div = 16; + if ((pwm->fade_time / steps) > (32768 / 512)) { + div512 = 1; + hz = 32768 / 512; + } + else { + div512 = 0; + hz = 32768 / 16; + } - hz = 32768 / div; - if (pwm->fade_time < ((steps * 1000) / hz)) - perstep = 1; - else - perstep = (hz * pwm->fade_time) / (steps * 1000); + perstep = (hz * pwm->fade_time) / (steps * 1000); if (perstep == 0) perstep = 1; else if (perstep > 63) perstep = 63; - if (steps > 252) { - lm8323_write_pwm(pwm, keepalive, 3, - PWM_RAMP((div == 512), perstep, 126, - direction), - PWM_RAMP((div == 512), perstep, 126, - direction), - PWM_RAMP((div == 512), perstep, steps - 252, - direction)); - } else if (steps > 126) { - lm8323_write_pwm(pwm, keepalive, 2, - PWM_RAMP((div == 512), perstep, 126, - direction), - PWM_RAMP((div == 512), perstep, steps - 126, - direction)); - } else { - lm8323_write_pwm(pwm, keepalive, 1, - PWM_RAMP((div == 512), perstep, steps, - direction)); + while (steps) { + int s; + + s = min(126, steps); + pwm_cmds[num_cmds++] = PWM_RAMP(div512, perstep, s, up); + steps -= s; } + lm8323_write_pwm(pwm, kill, num_cmds, pwm_cmds); + pwm->brightness = pwm->desired_brightness; + mutex_unlock(&pwm->lock); } static void lm8323_pwm_set_brightness(struct led_classdev *led_cdev, @@ -552,7 +557,9 @@ static void lm8323_pwm_set_brightness(struct led_classdev *led_cdev, struct lm8323_pwm *pwm = cdev_to_pwm(led_cdev); struct lm8323_chip *lm = pwm_to_lm8323(pwm); + mutex_lock(&pwm->lock); pwm->desired_brightness = brightness; + mutex_unlock(&pwm->lock); if (in_interrupt()) { schedule_work(&pwm->work); @@ -620,6 +627,8 @@ static int init_pwm(struct lm8323_chip *lm, int id, struct device *dev, pwm->fade_time = 0; pwm->brightness = 0; pwm->desired_brightness = 0; + pwm->running = 0; + mutex_init(&pwm->lock); if (name) { pwm->cdev.name = name; pwm->cdev.brightness_set = lm8323_pwm_set_brightness; @@ -917,7 +926,7 @@ static void __exit lm8323_exit(void) i2c_del_driver(&lm8323_i2c_driver); } -MODULE_AUTHOR("Daniel Stone"); +MODULE_AUTHOR("Timo O. Karjalainen , Daniel Stone"); MODULE_DESCRIPTION("LM8323 keypad driver"); MODULE_LICENSE("GPL"); -- 2.41.0