Re: [PATCH 5/8] Input: xpad: handle "present" and "gone" correctly
From: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Date: 2015-07-30 07:06:33
On Sat, Jul 11, 2015 at 01:47:45AM +0200, Pavel Rojtberg wrote:
quoted hunk ↗ jump to hunk
From: "Pierre-Loup A. Griffais" <redacted> Handle the "a new device is present" message properly by dynamically creating the input device at this point in time. This requires a workqueue as we are in interrupt context when we learn about this. Also properly disconnect any devices that we are told are removed. Signed-off-by: "Pierre-Loup A. Griffais" <redacted> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Pavel Rojtberg <redacted> --- drivers/input/joystick/xpad.c | 43 +++++++++++++++++++++++++++++++++++-------- 1 file changed, 35 insertions(+), 8 deletions(-)diff --git a/drivers/input/joystick/xpad.c b/drivers/input/joystick/xpad.c index 3349861..a9ff4c2 100644 --- a/drivers/input/joystick/xpad.c +++ b/drivers/input/joystick/xpad.c@@ -343,8 +343,12 @@ struct usb_xpad { int xtype; /* type of xbox device */ unsigned long pad_nr; /* the order x360 pads were attached */ const char *name; /* name of the device */ + struct work_struct work; /* init/remove device from callback */ }; +static int xpad_init_input(struct usb_xpad *xpad); +static void xpad_deinit_input(struct usb_xpad *xpad); + /* * xpad_process_packet *@@ -488,6 +492,22 @@ static void xpad360_process_packet(struct usb_xpad *xpad, static void xpad_identify_controller(struct usb_xpad *xpad); +static void presence_work_function(struct work_struct *work) +{ + struct usb_xpad *xpad = container_of(work, struct usb_xpad, work); + int error; + + if (xpad->pad_present) { + error = xpad_init_input(xpad); + if (error) { + /* complain only, not much else we can do here */ + dev_err(&xpad->dev->dev, "unable to init device\n"); + } + } else { + xpad_deinit_input(xpad); + } +} + /* * xpad360w_process_packet *@@ -504,13 +524,16 @@ static void xpad_identify_controller(struct usb_xpad *xpad); */ static void xpad360w_process_packet(struct usb_xpad *xpad, u16 cmd, unsigned char *data) { + int presence; + /* Presence change */ if (data[0] & 0x08) { - if (data[1] & 0x80) { - xpad->pad_present = 1; - xpad_identify_controller(xpad); - } else - xpad->pad_present = 0; + presence = (data[1] & 0x80) != 0; + + if (xpad->pad_present != presence) { + xpad->pad_present = presence; + schedule_work(&xpad->work); + } }
So what happens if we start without the input device, schedule it to be added and then receive a valid pad data packet before work item had a chance to run and input device is still not created? We are going crash and burn :( Thanks. -- Dmitry