Hi Elaine,
On 9 April 2017 at 20:09, Elaine Zhang zhangqing@rock-chips.com wrote:
On 04/10/2017 03:28 AM, Simon Glass wrote:
Hi,
On 7 April 2017 at 05:02, Kever Yang kever.yang@rock-chips.com wrote:
The latest kernel PWM drivers enable the polarity settings. When system run from U-Boot to kerenl, if there are differences in polarity set or duty cycle, the PMW will re-init: close -> set polarity and duty cycle -> enable the PWM. The power supply controled by pwm regulator may have voltage shaking, which lead to the system not stable.
Signed-off-by: Kever Yang kever.yang@rock-chips.com
drivers/power/regulator/pwm_regulator.c | 12 ++++++++++-- drivers/pwm/pwm-uclass.c | 10 ++++++++++ drivers/pwm/rk_pwm.c | 17 ++++++++++++++++- include/pwm.h | 9 +++++++++ 4 files changed, 45 insertions(+), 3 deletions(-)
If the generic uclass change and the rk change can be separated, it is good to do it.
Also we should have a test for pwm (test/dm/pwm.c). Are you able to do that? If not I could give it a try.
we have no plan to do it.
I've created something simple here. You can base your next series on u-boot-dm/pwm-working.
http://patchwork.ozlabs.org/patch/751254/
diff --git a/drivers/power/regulator/pwm_regulator.c b/drivers/power/regulator/pwm_regulator.c index 4875238..f8a6712 100644 --- a/drivers/power/regulator/pwm_regulator.c +++ b/drivers/power/regulator/pwm_regulator.c @@ -24,6 +24,8 @@ struct pwm_regulator_info { int pwm_id; /* the period of one PWM cycle */ int period_ns;
/* the polarity of one PWM */int polarity;Can you update the comment to indicate what the values mean? E.g. is 0 the normal polarity and 1 inverted?
0 : normal polarity 1 : inverted polarity I will update the comment next version.
struct udevice *pwm; /* initialize voltage of regulator */ unsigned int init_voltage;@@ -49,7 +51,7 @@ static int pwm_voltage_to_duty_cycle_percentage(struct udevice *dev, int req_uV) int max_uV = priv->max_voltage; int diff = max_uV - min_uV;
return 100 - (((req_uV * 100) - (min_uV * 100)) / diff);
return ((req_uV * 100) - (min_uV * 100)) / diff;}
static int pwm_regulator_get_voltage(struct udevice *dev)
@@ -67,6 +69,12 @@ static int pwm_regulator_set_voltage(struct udevice *dev, int uvolt)
duty_cycle = pwm_voltage_to_duty_cycle_percentage(dev, uvolt);
ret = pwm_set_init(priv->pwm, priv->pwm_id, priv->polarity);I wonder if it would be better to combine the polarity into the pwm_set_config() call? Then we can do everything in one call. If not then I think pwm_set_invert() would be a better name.
The polarity set only once, so we set it in pwm_set_init() call. Using pwm_set_invert, of course, is also possible.
OK, so that's why it should a separate call. Seems OK to me.
if (ret) {dev_err(dev, "Failed to init PWM\n");return ret;}ret = pwm_set_config(priv->pwm, priv->pwm_id, (priv->period_ns / 100) * duty_cycle,priv->period_ns); if (ret) { @@ -97,9 +105,9 @@ static int pwm_regulator_ofdata_to_platdata(struct udevice *dev) debug("%s: Cannot get PWM phandle: ret=%d\n", __func__, ret); return ret; }
/* TODO: pwm_id here from device tree if needed */ priv->period_ns = args.args[1];
priv->polarity = args.args[2];Does this mean that the binding has this argument and we have been ignoring it?
Can you bring in the DT binding file from Linux to U-Boot also?
Did you see this one?
Regards, Simon