Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753307AbbDIH5b (ORCPT ); Thu, 9 Apr 2015 03:57:31 -0400 Received: from mailout1.w1.samsung.com ([210.118.77.11]:10057 "EHLO mailout1.w1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751944AbbDIH53 (ORCPT ); Thu, 9 Apr 2015 03:57:29 -0400 X-AuditID: cbfec7f4-b7f106d0000013ec-cb-55263039f6ee Message-id: <552630E4.9030309@samsung.com> Date: Thu, 09 Apr 2015 09:57:24 +0200 From: Robert Baldyga User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.5.0 MIME-version: 1.0 To: Chanwoo Choi Cc: myungjoo.ham@samsung.com, rogerq@ti.com, linux-usb@vger.kernel.org, devicetree@vger.kernel.org, linux-kernel@vger.kernel.org, m.szyprowski@samsung.com Subject: Re: [PATCH v3 2/4] extcon: usb-gpio: add support for VBUS detection References: <1427980385-21285-1-git-send-email-r.baldyga@samsung.com> <1427980385-21285-3-git-send-email-r.baldyga@samsung.com> <5525E012.5050207@samsung.com> In-reply-to: <5525E012.5050207@samsung.com> Content-type: text/plain; charset=windows-1252 Content-transfer-encoding: 7bit X-Brightmail-Tracker: H4sIAAAAAAAAA+NgFtrALMWRmVeSWpSXmKPExsVy+t/xa7qWBmqhBofOiFpc//Kc1WL+kXOs Fpd3zWGzWLSsldli7ZG77Ba3G1ewWfQ80nJg9+jbsorR4/iN7UwenzfJBTBHcdmkpOZklqUW 6dslcGU0XOtiKjirUbF9y2zmBsbNsl2MnBwSAiYSay7vZ4GwxSQu3FvP1sXIxSEksJRRomNj PzuE85FRYuf2fsYuRg4OXgEtiRXzs0EaWARUJf4t+QDWzCagI7Hl+wSwElGBCInblzlBwrwC ghI/Jt8DKxER0JCY+fcKI8hIZoF5jBKL575nB6kXFvCRWHiDFWLVIkaJIxufMoE0cApoS3Se vsUKUsMsoCdx/6IWSJhZQF5i85q3zBMYBWYhWTELoWoWkqoFjMyrGEVTS5MLipPScw31ihNz i0vz0vWS83M3MUJC+csOxsXHrA4xCnAwKvHwWhxTCRViTSwrrsw9xCjBwawkwpsspRYqxJuS WFmVWpQfX1Sak1p8iJGJg1OqgVGd43jXozdsZmkhKYyP1p/ZfkHu36zf+/f/kFb02vOxde3W eVd6qy5/Ps7ak7v+gfZ3vb8WsTFGtd9TWgJfztT47HD1f7GTw76FtzimRb17sL3T5Y2i4Ncq 53bJvaZHTUU4u6+dDJh3bdX+7n3PGJ/ebjPWDJ9fE2a+IrnnS3Nknafk482ximeUWIozEg21 mIuKEwHRXy92QwIAAA== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5292 Lines: 155 Hi Chanwoo, On 04/09/2015 04:12 AM, Chanwoo Choi wrote: > Hi Robert, > > On 04/02/2015 10:13 PM, Robert Baldyga wrote: >> This patch adds VBUS pin detection support to extcon-usb-gpio driver. >> It allows to use this driver with boards which have both VBUS and ID >> pins, or only one of them. >> >> Following table of states presents relationship between this signals >> and detected cable type: >> >> State | ID | VBUS >> ---------------------------------------- >> [1] USB | H | H >> [2] none | H | L >> [3] USB & USB-HOST | L | H >> [4] USB-HOST | L | L >> >> In case we have only one of these signals: >> - VBUS only - we want to distinguish between [1] and [2], so ID is always 1. >> - ID only - we want to distinguish between [1] and [4], so VBUS = ID. >> >> Signed-off-by: Robert Baldyga >> --- >> drivers/extcon/extcon-usb-gpio.c | 169 +++++++++++++++++++++++++++------------ >> 1 file changed, 119 insertions(+), 50 deletions(-) >> >> diff --git a/drivers/extcon/extcon-usb-gpio.c b/drivers/extcon/extcon-usb-gpio.c >> index f6aa99d..baf7add 100644 >> --- a/drivers/extcon/extcon-usb-gpio.c >> +++ b/drivers/extcon/extcon-usb-gpio.c >> @@ -32,7 +32,9 @@ struct usb_extcon_info { >> struct extcon_dev *edev; >> >> struct gpio_desc *id_gpiod; >> + struct gpio_desc *vbus_gpiod; >> int id_irq; >> + int vbus_irq; >> >> unsigned long debounce_jiffies; >> struct delayed_work wq_detcable; >> @@ -52,40 +54,51 @@ static const char *usb_extcon_cable[] = { >> NULL, >> }; >> >> +/* >> + * "USB" = VBUS and "USB-HOST" = !ID, so we have: >> + * >> + * State | ID | VBUS >> + * ---------------------------------------- >> + * [1] USB | H | H >> + * [2] none | H | L >> + * [3] USB & USB-HOST | L | H >> + * [4] USB-HOST | L | L >> + * >> + * In case we have only one of these signals: >> + * - VBUS only - we want to distinguish between [1] and [2], so ID is always 1. >> + * - ID only - we want to distinguish between [1] and [4], so VBUS = ID. >> + */ >> + >> static void usb_extcon_detect_cable(struct work_struct *work) >> { >> int id; >> + int vbus; >> struct usb_extcon_info *info = container_of(to_delayed_work(work), >> struct usb_extcon_info, >> wq_detcable); >> >> - /* check ID and update cable state */ >> - id = gpiod_get_value_cansleep(info->id_gpiod); >> - if (id) { >> - /* >> - * ID = 1 means USB HOST cable detached. >> - * As we don't have event for USB peripheral cable attached, >> - * we simulate USB peripheral attach here. >> - */ >> + /* check ID and VBUS and update cable state */ >> + >> + id = info->id_gpiod ? >> + gpiod_get_value_cansleep(info->id_gpiod) : 1; >> + >> + vbus = info->vbus_gpiod ? >> + gpiod_get_value_cansleep(info->vbus_gpiod) : id; >> + >> + /* at first we clean states which are no longer active */ >> + if (id) >> extcon_set_cable_state(info->edev, >> - usb_extcon_cable[EXTCON_CABLE_USB_HOST], >> - false); >> + usb_extcon_cable[EXTCON_CABLE_USB_HOST], false); >> + if (!vbus) >> extcon_set_cable_state(info->edev, >> - usb_extcon_cable[EXTCON_CABLE_USB], >> - true); >> - } else { >> - /* >> - * ID = 0 means USB HOST cable attached. >> - * As we don't have event for USB peripheral cable detached, >> - * we simulate USB peripheral detach here. >> - */ >> + usb_extcon_cable[EXTCON_CABLE_USB], false); >> + >> + if (!id) >> extcon_set_cable_state(info->edev, >> - usb_extcon_cable[EXTCON_CABLE_USB], >> - false); >> + usb_extcon_cable[EXTCON_CABLE_USB_HOST], true); >> + if (vbus) >> extcon_set_cable_state(info->edev, >> - usb_extcon_cable[EXTCON_CABLE_USB_HOST], >> - true); >> - } >> + usb_extcon_cable[EXTCON_CABLE_USB], true); >> } > > Looks good to me of this patch. > > But, I have one question about case[3] > > If id is low and vbus is high, this patch will update the state of both USB and USB-HOST cable as attached state. > Is it possible that two different cables (both USB and USB-HOST) are connected to one port simultaneously? > It's because state of single USB cable connection cannot be completely described using single extcon cable. USB cable state has two bits (VBUS and ID), so we need to use two cables for single cable connection. We use following convention: cable "USB" = VBUS cable "USB-HOST" = !ID. In fact it would be better to have cables named "USB-VBUS" and "USB-ID" - in this convention it would be more clear. > >> + * "USB" = VBUS and "USB-HOST" = !ID, so we have: >> + * >> + * State | ID | VBUS >> + * ---------------------------------------- >> + * [1] USB | H | H >> + * [2] none | H | L >> + * [3] USB & USB-HOST | L | H >> + * [4] USB-HOST | L | L >> + * > Thanks, Robert Baldyga -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/