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 > <chunfeng.yun@xxxxxxxxxxxx> wrote: > > From bf48dcd9cb254576cfea373c9a5d2ab996408895 Mon Sep 17 00:00:00 2001 > > From: Chunfeng Yun <chunfeng.yun@xxxxxxxxxxxx> > > 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@xxxxxxxxxxxxxxx > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > > -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
