From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751474AbdJCWwf (ORCPT ); Tue, 3 Oct 2017 18:52:35 -0400 Received: from 6.mo5.mail-out.ovh.net ([178.32.119.138]:56128 "EHLO 6.mo5.mail-out.ovh.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750865AbdJCWwe (ORCPT ); Tue, 3 Oct 2017 18:52:34 -0400 X-Greylist: delayed 8824 seconds by postgrey-1.27 at vger.kernel.org; Tue, 03 Oct 2017 18:52:34 EDT Subject: Re: [Regulator] Request for clarification - GPIO controlled regulator, USB VBUS, To: Dmitry Torokhov Cc: "linux-input@vger.kernel.org" , "linux-kernel@vger.kernel.org" , Liam Girdwood , Mark Brown References: From: =?UTF-8?Q?=c5=81ukasz_Majewski?= Message-ID: <5343f07a-e22f-dce9-0cb2-a67723345511@majess.pl> Date: Tue, 3 Oct 2017 22:25:23 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.2.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit X-Ovh-Tracer-Id: 17453700359809057509 X-VR-SPAMSTATE: OK X-VR-SPAMSCORE: -100 X-VR-SPAMCAUSE: gggruggvucftvghtrhhoucdtuddrfeelledrkeejgdduvdduucetufdoteggodetrfdotffvucfrrhhofhhilhgvmecuqfggjfdpvefjgfevmfevgfenuceurghilhhouhhtmecufedttdenucesvcftvggtihhpihgvnhhtshculddquddttddm Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Dmitry, > Hi Łukasz, > > On Tue, Oct 3, 2017 at 9:58 AM, Łukasz Majewski wrote: >> Dear All, >> >> Maybe somebody could shed some light to following issue: >> >> On my setup I do have USB connected touchscreen powered from VBUS. >> >> The VBUS power is controlled by a GPIO pin, which in turn is governed by >> regulator API: >> >> reg_usbh1_vbus: usb-h1-vbus { >> compatible = "regulator-fixed"; >> gpio = <&gpio3 31 GPIO_ACTIVE_LOW>; >> pinctrl-names = "default"; >> pinctrl-0 = <&pinctrl_usbh1_vbus>; >> regulator-name = "usb_h1_vbus"; >> regulator-min-microvolt = <5000000>; >> regulator-max-microvolt = <5000000>; >> regulator-settling-time-us = <100000>; >> }; >> >> >> This regulator is then passed to USB controller: >> >> &usbh1 { >> vbus-supply = <®_usbh1_vbus>; >> >> } >> >> The regulator API starts VBUS -> USB host get info about the VBUS present >> and starts enumeration of the USB device. >> >> >> I would like to ask if there is any recommended way to remove VBUS power and >> have a way to force from user space the touchscreen (re-)enumeration? >> >> As fair as I know the Regulator API is RO on purpose, so I cannot toggle >> vbus from there. >> >> I could use hacks presented here (the userspace-regulator API): >> https://patchwork.ozlabs.org/patch/374912/ >> https://lkml.org/lkml/2014/7/30/357 >> >> but for some reason they did not find the way to the upstream. Also it seems >> like such approach is for testing, not for production system. >> >> >> I could write a "dummy" regulator driver, which would export control API to >> /dev/sys/proc. >> Something like: >> http://elixir.free-electrons.com/linux/latest/source/drivers/usb/phy/phy-fsl-usb.c >> >> (but with opposite way). >> >> or ./drivers/input/misc/regulator-haptic.c >> >> >> I've also tried the "usb" power control tricks; >> >> echo "0" > /sys/bus/usb/devices/usb1/power/autosuspend_delay_ms >> echo "auto" > /sys/bus/usb/devices/usb1/power/control >> >> But without any effect (probably because of above dependencies). >> >> >> >> Have I overlooked something? Maybe there is any other mainline code, which I >> could reuse? >> >> >> My goal is to reuse as much as possible from ML and avoid developing any new >> code :-) >> > > Please start from the beginning: it is not quite clear why you want > the touchscreen to be re-enumerated. The above setup generally works. However, from time to time I do encounter some HID multi-touch driver initialization errors, which render the touchscreen unusable - e.g: usb 1-1: input irq status -75 received usb 1-1: reset low-speed USB device number 2 using ci_hdrc expected 16 bytes, got -1 or hid-generic 0003:19E2:2533.0002: unknown main item tag 0x0 hid-generic 0003:19E2:2533.0002: unknown main item tag 0x0 hid-generic 0003:19E2:2533.0002: unbalanced collection at end of report description hid-generic: probe of 0003:19E2:2533.0002 failed with error -22 I've added 100 ms settle time for the VBUS regulator, but I'm not sure if it will fix this issue (I'm going to inspect VBUS voltage with oscilloscope). Since I do have above errors, I thought that it would be feasible to have a "mean" to re-set VBUS voltage and force enumeration of the device. I'm quite curious how USB connected touchscreens are controlled with USB's VBUS not accessible from user-space out of the box? > > Thanks. > -- Best regards. Łukasz Majewski