Merge "Document the current MAX_USBFS_BULK_SIZE situation."

 * SUCH DAMAGE.

 */

#include <ctype.h>

#include <dirent.h>

#include <errno.h>

#include <fcntl.h>

#include <pthread.h>

#include <stdio.h>

#include <stdlib.h>

#include <unistd.h>

#include <string.h>

#include <sys/ioctl.h>

#include <sys/stat.h>

#include <sys/types.h>

#include <dirent.h>

#include <fcntl.h>

#include <errno.h>

#include <pthread.h>

#include <ctype.h>

#include <unistd.h>

#include <linux/usbdevice_fs.h>

#include <linux/usbdevice_fs.h>

#include <linux/version.h>

#if LINUX_VERSION_CODE > KERNEL_VERSION(2, 6, 20)

#include <linux/usb/ch9.h>

#else

#include <linux/usb_ch9.h>

#endif

#include <asm/byteorder.h>

#include "fastboot.h"

#include "usb.h"

#define DBG1(x...)

#endif

/* The max bulk size for linux is 16384 which is defined

 * in drivers/usb/core/devio.c.

 */

// Kernels before 3.3 have a 16KiB transfer limit. That limit was replaced

// with a 16MiB global limit in 3.3, but each URB submitted required a

// contiguous kernel allocation, so you would get ENOMEM if you tried to

// send something larger than the biggest available contiguous kernel

// memory region. 256KiB contiguous allocations are generally not reliable

// on a device kernel that has been running for a while fragmenting its

// memory, but that shouldn't be a problem for fastboot on the host.

// In 3.6, the contiguous buffer limit was removed by allocating multiple

// 16KiB chunks and having the USB driver stitch them back together while

// transmitting using a scatter-gather list, so 256KiB bulk transfers should

// be reliable.

// 256KiB seems to work, but 1MiB bulk transfers lock up my z620 with a 3.13

// kernel.

#define MAX_USBFS_BULK_SIZE (16 * 1024)

struct usb_handle