From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lee Jones Subject: Re: [PATCH v2 5/8] dt-bindings: mfd: axp20x: Add software based soft_start for AXP209 LDO3 Date: Fri, 21 Dec 2018 08:40:10 +0000 Message-ID: <20181221084010.GR4497@dell> References: <25e67fe9b5397aa5f11bdd7026e4ae6be51dd18b.1544512919.git-series.plaes@plaes.org> Reply-To: lee.jones-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Return-path: Sender: linux-sunxi-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org Content-Disposition: inline In-Reply-To: <25e67fe9b5397aa5f11bdd7026e4ae6be51dd18b.1544512919.git-series.plaes-q/aMd4JkU83YtjvyW6yDsg@public.gmane.org> List-Post: , List-Help: , List-Archive: , List-Unsubscribe: , To: Priit Laes Cc: Rob Herring , Mark Rutland , Chen-Yu Tsai , Maxime Ripard , Liam Girdwood , Mark Brown , devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, Olliver Schinagl , linux-sunxi List-Id: devicetree@vger.kernel.org On Tue, 11 Dec 2018, Priit Laes wrote: > From: Olliver Schinagl >=20 > In the past, there have been words on various lists that if LDO3 is > disabled in u-boot, but enabled in the DTS, the axp209 driver would > fail to continue/hang. Several enable/disable patches have been > issues to devicetree's in both the kernel and u-boot to address > this issue. >=20 > What really happened however, was that the AXP209 shuts down without > a notice and without setting an interrupt. This is caused when LDO3 > gets overloaded, for example with large capacitors on the LDO3 output. >=20 > Normally, we would expect that AXP209 would source 200 mA as per > datasheet and set and trigger an interrupt when being overloaded. > For some reason however, this does not happen. >=20 > As a work-around, implement software-based 'regulator-soft-start' > property for AXP209 LDO3 regulator, which is used to first bring up > the LDO3 to the lowest possible voltage and then enable the LDO. >=20 > After that, we can set the requested voltage as usual. >=20 > Combining this setting with the regulator-ramp-delay allows LDO3 to > come up slowly and staggered, potentially reducing overall inrush current= . >=20 > Signed-off-by: Olliver Schinagl > Signed-off-by: Priit Laes > --- > Documentation/devicetree/bindings/mfd/axp20x.txt | 3 +++ > 1 file changed, 3 insertions(+) For my own reference: Acked-for-MFD-by: Lee Jones --=20 Lee Jones [=E6=9D=8E=E7=90=BC=E6=96=AF] Linaro Services Technical Lead Linaro.org =E2=94=82 Open source software for ARM SoCs Follow Linaro: Facebook | Twitter | Blog --=20 You received this message because you are subscribed to the Google Groups "= linux-sunxi" group. To unsubscribe from this group and stop receiving emails from it, send an e= mail to linux-sunxi+unsubscribe-/JYPxA39Uh5TLH3MbocFF+G/Ez6ZCGd0@public.gmane.org For more options, visit https://groups.google.com/d/optout.