From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AG47ELuDeuB2AzY7mS8xUHXLlz1gOyQ9pJ5jqNZoIdyG2mrtbvKz6rJV7bdKCKnDW4rtoLsUPSV6 ARC-Seal: i=1; a=rsa-sha256; t=1521015601; cv=none; d=google.com; s=arc-20160816; b=F0NK9PLEBMCs3KANDeI4Sg34eov3sIITZDbb2svRYMAuuthxW7t+3S0FtIh/KQS7Cs ZFyFzFeEkdWcMkLnzkdLotb/kwgvhe+OAxbePC6Me9WhZrSKNI7LUtXYlQ+o9a3MO1RI W0S49oWi1UXFCkDBxoThDDUMC+vOfYBzbkDSSn2wkK7ISlpCozvFBAqijHXF/BHx0gU/ mvLHgCHm+pB+doShNyedKvvKTR+yTIExdp4Ns5UEu9araXc2mGPVh0BnnaxBRMWPCLun ELxjmVxFPdh2XgX0zAL5Y+MGFxfXVhhZmtbwF9UQ+WiSugKvoOkoKo6EzAwNMhsHh/0f 6e2Q== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=mime-version:content-transfer-encoding:references:in-reply-to:date :cc:to:from:subject:message-id:arc-authentication-results; bh=nmYXI0SxvNWPydiP22L4J4Bibf/4YNAHpqQBhHSP2Ko=; b=YnZMWJHywJrVOgZKu+3nVI+6spHC/xbKstsHjPa2P+Nimrud7udC3JtkUbAnhcohDe 8CCeGC7isA7eT+9XaO1fjlS7zfq/Rs16QjXzFDtZLnoXr/h3rNknjwSP+txPcDCWU1PR q6Z4vNgBgybme2ZsVnsaYiCC16XI1ZlOKAmRTn4vVZU/dHBcQUJfu10aJJU1iHxrrAW4 oogywwZuKeFRL/4DIZpx5rCVKVclfdrWbJCne+3gtfkLarGmPElJQwQECpjlcEyryEJL e2cTJkScZZftII3lrzg63Hb8ro/PlioOKtCMZO33zx0TulIRCasI322Z7gClQV4NreDH WCmA== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of chunfeng.yun@mediatek.com designates 1.203.163.81 as permitted sender) smtp.mailfrom=chunfeng.yun@mediatek.com Authentication-Results: mx.google.com; spf=pass (google.com: domain of chunfeng.yun@mediatek.com designates 1.203.163.81 as permitted sender) smtp.mailfrom=chunfeng.yun@mediatek.com X-UUID: 05667290370d4e1f89f63586432b55c1-20180314 Message-ID: <1521015535.3717.26.camel@mhfsdcap03> Subject: Re: [PATCH] Add Apple Carplay driver From: Chunfeng Yun To: Matthew Dharm CC: Greg Kroah-Hartman , Matthias Brugger , Heikki Krogerus , Serge Semin , Guenter Roeck , Kate Stewart , Thomas Gleixner , "Alan Stern" , , , , Date: Wed, 14 Mar 2018 16:18:55 +0800 In-Reply-To: References: <1521007356-12306-1-git-send-email-chunfeng.yun@mediatek.com> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.3-0ubuntu6 Content-Transfer-Encoding: 7bit MIME-Version: 1.0 X-MTK: N X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1594891852474932951?= X-GMAIL-MSGID: =?utf-8?q?1594900455467993368?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: On Tue, 2018-03-13 at 23:53 -0700, Matthew Dharm wrote: > Why is this a kernel-level driver, rather than a userspace application > that uses libusb to send the single vendor-specific command required? > Since this command would be applicable to many CarPlay devices, with > many different VID/PIDs, it would seem to make more sense as a > userspace app that took a reference to a USB device or VID/PID. Sorry, I'm not familiar with libusb. But after I roughly read a simple example using libusb, it indeed can be realized by a userspace driver. Thanks for your useful comments > > Matt > > On Tue, Mar 13, 2018 at 11:02 PM, Chunfeng Yun > wrote: > > From bf48dcd9cb254576cfea373c9a5d2ab996408895 Mon Sep 17 00:00:00 2001 > > From: Chunfeng Yun > > Date: Tue, 13 Mar 2018 11:47:38 +0800 > > Subject: [PATCH] Add Apple Carplay driver > > > > Some Apple devices which support Carplay can enter USB Host Mode from USB > > Device Mode after receiving a specific USB Vendor Request. There is a > > requirement apply to accesssories that support the USB dual role switch > > feature, and must have a USB-A receptacle that is capable of functioning > > in both USB Host and USB Device roles. > > It means that the driver should supports manual Dual-Role switch, due to > > no IDDIG pin is avaliable. > > > > There is no suitable place to add this spicific USB Vendor Request, so > > here I extract a single driver which allow user force to send it by a debug > > interface when need it, and keep it independent on USB Dual-Role Controller > > Drivers. > > But to implement carplay feature, there are some requirments for USB Dual-Role > > Driver: > > 1. supports manual dual-role switch, such as, by a debug interface; > > 2. keep vbus alive even when switch host into device mode; > > > > More information please refer to "Chapter 46. USB Role Switch" in > > MFI Accessroy Interface Specification.pdf > > > > Chunfeng Yun (1): > > usb: misc: supports Apple Carplay driver > > > > drivers/usb/misc/Kconfig | 9 +++ > > drivers/usb/misc/Makefile | 1 + > > drivers/usb/misc/carplay.c | 193 ++++++++++++++++++++++++++++++++++++++++++++ > > 3 files changed, 203 insertions(+) > > create mode 100644 drivers/usb/misc/carplay.c > > > > -- > > 1.7.9.5 > > > > > > -- > > To unsubscribe from this list: send the line "unsubscribe linux-usb" in > > the body of a message to majordomo@vger.kernel.org > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > >