Messages in this thread | | | Subject | Re: [PATCH v2] regulator: s2mps11: Set default ramp delay for S2MPS11 LDOs | From | Javier Martinez Canillas <> | Date | Mon, 18 Apr 2016 13:03:22 -0400 |
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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, -- Javier Martinez Canillas Open Source Group Samsung Research America
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