| Message ID | 1460986390-9674-1-git-send-email-k.kozlowski@samsung.com (mailing list archive) |
|---|---|
| State | Not Applicable |
| Headers | show |
Hello Krzysztof, On 04/18/2016 09:33 AM, Krzysztof Kozlowski wrote: > Driver did not provide default value for ramp delay for LDOs which lead > to warning in dmesg, e.g. on Odroid XU4: > > [ 1.486076] vdd_ldo9: ramp_delay not set > [ 1.506875] vddq_mmc2: ramp_delay not set > [ 1.523766] vdd_ldo15: ramp_delay not set > [ 1.544702] vdd_sd: ramp_delay not set > > The datasheet for all the S2MPS1x family is inconsistent here and does > not specify unambiguously the value of ramp delay for LDO. It mentions > 30 mV/us in one timing diagram but then omits it completely in LDO > regulator characteristics table (it is specified for bucks). > > However the vendor kernels for Galaxy S5 and Odroid XU3 use values of 12 > mV/us or 24 mV/us. > > Without the ramp delay value the consumers do not wait for voltage > settle after changing it. Although the proper value of ramp delay for > LDOs is unknown, it seems safer to use at least some value from > reference kernel than to leave it unset. > > Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com> > Reviewed-by: Javier Martinez Canillas <javier@osg.samsung.com> Best regards,
diff --git a/drivers/regulator/s2mps11.c b/drivers/regulator/s2mps11.c index 64a262f10845..02fb6b4ea820 100644 --- a/drivers/regulator/s2mps11.c +++ b/drivers/regulator/s2mps11.c @@ -267,6 +267,7 @@ static struct regulator_ops s2mps11_buck_ops = { .ops = &s2mps11_ldo_ops, \ .type = REGULATOR_VOLTAGE, \ .owner = THIS_MODULE, \ + .ramp_delay = RAMP_DELAY_12_MVUS, \ .min_uV = MIN_800_MV, \ .uV_step = step, \ .n_voltages = S2MPS11_LDO_N_VOLTAGES, \ diff --git a/include/linux/mfd/samsung/core.h b/include/linux/mfd/samsung/core.h index 6bc4bcd488ac..5a23dd4df432 100644 --- a/include/linux/mfd/samsung/core.h +++ b/include/linux/mfd/samsung/core.h @@ -30,6 +30,9 @@ #define MIN_600_MV 600000 #define MIN_500_MV 500000 +/* Ramp delay in uV/us */ +#define RAMP_DELAY_12_MVUS 12000 + /* Macros to represent steps for LDO/BUCK */ #define STEP_50_MV 50000 #define STEP_25_MV 25000
Driver did not provide default value for ramp delay for LDOs which lead to warning in dmesg, e.g. on Odroid XU4: [ 1.486076] vdd_ldo9: ramp_delay not set [ 1.506875] vddq_mmc2: ramp_delay not set [ 1.523766] vdd_ldo15: ramp_delay not set [ 1.544702] vdd_sd: ramp_delay not set The datasheet for all the S2MPS1x family is inconsistent here and does not specify unambiguously the value of ramp delay for LDO. It mentions 30 mV/us in one timing diagram but then omits it completely in LDO regulator characteristics table (it is specified for bucks). However the vendor kernels for Galaxy S5 and Odroid XU3 use values of 12 mV/us or 24 mV/us. Without the ramp delay value the consumers do not wait for voltage settle after changing it. Although the proper value of ramp delay for LDOs is unknown, it seems safer to use at least some value from reference kernel than to leave it unset. Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com> --- Changes since v1: 1. Instead of removing the implementation of .set_voltage_time_sel() callback, use some value from reference kernel. --- drivers/regulator/s2mps11.c | 1 + include/linux/mfd/samsung/core.h | 3 +++ 2 files changed, 4 insertions(+)