From mboxrd@z Thu Jan 1 00:00:00 1970 From: Hans de Goede Subject: Re: [linux-sunxi] Re: [PATCH] ARM: dts: sun4i: Add dts file for the pov protab2-ips9 tablet Date: Tue, 8 Sep 2015 09:45:52 +0200 Message-ID: <55EE9230.70209@redhat.com> References: <1441441319-10658-1-git-send-email-hdegoede@redhat.com> <20150906163023.GR31584@lukather> <55ED3739.609@redhat.com> <20150907205603.GX31584@lukather> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20150907205603.GX31584@lukather> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Maxime Ripard , Wolfram Sang Cc: linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org, devicetree , linux-sunxi-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org List-Id: devicetree@vger.kernel.org Hi, On 07-09-15 22:56, Maxime Ripard wrote: > On Mon, Sep 07, 2015 at 09:05:29AM +0200, Hans de Goede wrote: >>>> +®_ldo3 { >>>> + /* >>>> + * We need to always power the camera sensor, otherwhise all access >>>> + * to i2c1 is blocked. >>>> + */ >>>> + regulator-always-on; >>>> + regulator-min-microvolt = <2800000>; >>>> + regulator-max-microvolt = <2800000>; >>>> + regulator-name = "vdd-csi"; >>>> +}; >>> >>> What is connected on i2c1 ? Just the camera sensor? or it has some >>> other devices there? >> >> The bma250 accelerometer sits there, and the kernel already has a driver >> for it. That driver needs to have devicetree binding support added, and >> then we should be able to use the accelerometer. > > Ok, so if this regulator is disable, you can't access the other > devices as well, right? Right, the controller reports the bus as being stuck. > Do you know why? Is it the regulator providing > the pull-up voltage? I've tried enabling the pull ups on the SoC i2c pins, so I do not think that it is that, it seems that somehow when not powered the camera sensor is actively keeping the lines low. Either it has multiple power planes, or it is using normally-on fet-s between ground and its i2c lines. Regards, Hans -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html