implemented proof-of-concept device reset

Makefile

@@ -2,7 +2,7 @@ CC = clang
 CFLAGS = -std=c99 -Wall -Wextra
 LDFLAGS = -lusb-1.0
 
-SRCS = elgato-gchd.c commands.c init_720p.c init_1080p.c remove.c
+SRCS = elgato-gchd.c commands.c init.c init_720p.c init_1080p.c remove.c
 OBJS = $(SRCS:.c=.o)
 EXEC = elgato-gchd
 

README.md

@@ -61,7 +61,7 @@ Usage
 
 According to your HDMI source, run `./elgato-gchd -r 720p` or
 `./elgato-gchd -r 1080p` with root permissions in a terminal and leave it open.
-This driver will create a new file `/tmp/elgato-gchd.ts`.
+This command will create a new file `/tmp/elgato-gchd.ts`.
 
 Please note, that this file is actually a FIFO pipe and will not grow. You will
 need an external program to record footage.
@@ -70,9 +70,11 @@ You can open up this file using any media player, which supports reading from
 pipes. There will be a slight delay, which is hardware limited and can not be
 worked around.
 
-After closing the file, you will not be able to reopen it again. You will need
-to stop the terminal using "Ctrl + C", disconnect and reconnect your Elgato Game
-Capture HD's USB cable and start over again.
+If you're done using this driver, close the file. Then stop the terminal using
+"Ctrl + C" and wait for the program to successfully terminate. The driver is
+resetting your device, so it can be used again. If you interrupt this step, it
+will leave your device in an undefined state and you will need to replug your
+device, to manually reset it.
 
 Currently, 1080p30 and 720p60 are supported.
 

commands.c

@@ -7,6 +7,7 @@
 
 #include <stdio.h>
 #include <stdlib.h>
+#include <unistd.h>
 
 #include <libusb-1.0/libusb.h>
 
@@ -20,6 +21,17 @@ void read_config(uint8_t bRequest, uint16_t wValue, uint16_t wIndex, uint16_t wL
 	free(recv);
 }
 
+int read_config4(uint8_t bRequest, uint16_t wValue, uint16_t wIndex, unsigned char data0, unsigned char data1, unsigned char data2, unsigned char data3) {
+	unsigned char recv[4];
+	libusb_control_transfer(devh, 0xc0, bRequest, wValue, wIndex, recv, 4, 0);
+
+	if (recv[0] == data0 && recv[1] == data1 && recv[2] == data2 && recv[3] == data3) {
+		return 1;
+	}
+
+	return 0;
+}
+
 void write_config2(uint8_t bRequest, uint16_t wValue, uint16_t wIndex, unsigned char data0, unsigned char data1) {
 	unsigned char send[2] = {data0, data1};
 	libusb_control_transfer(devh, 0x40, bRequest, wValue, wIndex, send, 2, 0);
@@ -168,3 +180,11 @@ void dlfirm(const char *file) {
 
 	fclose(bin);
 }
+
+void receive_data() {
+	int transfer;
+	unsigned char data[DATA_BUF] = {0};
+
+	libusb_bulk_transfer(devh, 0x81, data, DATA_BUF, &transfer, 5000);
+	write(fd_fifo, (char *)data, DATA_BUF);
+}

commands.h

@@ -11,12 +11,13 @@
 #include <stdint.h>
 
 // scmd commands
-#define SCMD_IDLE			1
-#define SCMD_INIT			4
+#define SCMD_IDLE		1
+#define SCMD_INIT		4
 #define SCMD_STATE_CHANGE	5
 
-// deprecated functions. Getting replaced by reverse engineered functions.
+// Getting replaced by reverse engineered functions.
 void read_config(uint8_t bRequest, uint16_t wValue, uint16_t wIndex, uint16_t wLength);
+int read_config4(uint8_t bRequest, uint16_t wValue, uint16_t wIndex, unsigned char data0, unsigned char data1, unsigned char data2, unsigned char data3);
 void write_config2(uint8_t bRequest, uint16_t wValue, uint16_t wIndex, unsigned char data0, unsigned char data1);
 void write_config3(uint8_t bRequest, uint16_t wValue, uint16_t wIndex, unsigned char data0, unsigned char data1, unsigned char data2);
 void write_config4(uint8_t bRequest, uint16_t wValue, uint16_t wIndex, unsigned char data0, unsigned char data1, unsigned char data2, unsigned char data3);
@@ -79,4 +80,6 @@ void slsi(uint16_t wIndex, uint16_t data);
  */
 void dlfirm(const char *file);
 
+void receive_data();
+
 #endif

common.h

@@ -16,5 +16,7 @@
 #define FW_MB86H57_H58_ENC	"firmware/mb86h57_h58_enc_h.bin"
 
 struct libusb_device_handle *devh;
+extern int fd_fifo;
+extern int init_has_been_run;
 
 #endif

elgato-gchd.c

@@ -39,6 +39,7 @@
 static volatile sig_atomic_t is_running = 1;
 int libusb_ret = 1;
 int fd_fifo = 0;
+int init_has_been_run = 0;
 char *fifo_path = "/tmp/elgato_gchd.ts";
 
 enum video_resoltion {
@@ -47,6 +48,8 @@ enum video_resoltion {
 };
 
 void sig_handler(int sig) {
+	fprintf(stderr, "Stop signal received. Do not interrupt or unplug your device.\n");
+
 	switch(sig) {
 		case SIGINT:
 			is_running = 0;
@@ -104,17 +107,13 @@ int get_interface() {
 	return 0;
 }
 
-void receive_data() {
-	int transfer;
-	unsigned char data[DATA_BUF] = {0};
-
-	libusb_bulk_transfer(devh, 0x81, data, DATA_BUF, &transfer, 5000);
-	write(fd_fifo, (char *)data, DATA_BUF);
-}
-
 void clean_up() {
 	if (devh) {
-		remove_elgato();
+		if (init_has_been_run) {
+			remove_elgato();
+			fprintf(stderr, "Device has been reset.\n");
+		}
+
 		libusb_release_interface(devh, INTERFACE_NUM);
 		libusb_close(devh);
 	}
@@ -125,6 +124,8 @@ void clean_up() {
 
 	close(fd_fifo);
 	unlink(fifo_path);
+
+	fprintf(stderr, "Clean up done. Terminating\n");
 }
 
 int main(int argc, char *argv[]) {
@@ -188,18 +189,26 @@ int main(int argc, char *argv[]) {
 	// create the FIFO (also known as named pipe)
 	mkfifo(fifo_path, 0644);
 
+	fprintf(stderr, "%s has been created. Waiting for user to open it.\n", fifo_path);
+
 	// open FIFO
 	fd_fifo = open(fifo_path, O_WRONLY);
 
 	// set device configuration
-	switch (resolution) {
-		case v720p: configure_dev_720p(); break;
-		case v1080p: configure_dev_1080p(); break;
-		default: clean_up();
+	if (is_running) {
+		fprintf(stderr, "Running. Initializing device.\n");
+
+		switch (resolution) {
+			case v720p: configure_dev_720p(); break;
+			case v1080p: configure_dev_1080p(); break;
+			default: clean_up();
+		}
+
+		fprintf(stderr, "Streaming data from device now.\n");
 	}
 
 	// receive audio and video from device
-	while(is_running) {
+	while (is_running) {
 		receive_data();
 	}