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libusbhost: Fix problem reading USB string descriptors on some quirky devices 

Some devices fail to send USB string descriptors if you attempt to read more
than 255 bytes

Bug: 21871761
Change-Id: Id5b8865179f80523f0ad5b6028d49dd99db2b36b
This commit is contained in:
Mike Lockwood 2015-06-18 13:38:31 -07:00
parent d50393057a
commit 0dd1aab7b5
1 changed files with 5 additions and 2 deletions
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7
libusbhost/usbhost.c
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@ -56,6 +56,9 @@
#define USB_FS_ID_SCANNER USB_FS_DIR "/%d/%d"
#define USB_FS_ID_FORMAT USB_FS_DIR "/%03d/%03d"
// Some devices fail to send string descriptors if we attempt reading > 255 bytes
#define MAX_STRING_DESCRIPTOR_LENGTH 255
// From drivers/usb/core/devio.c
// I don't know why this isn't in a kernel header
#define MAX_USBFS_BUFFER_SIZE 16384
@ -449,8 +452,8 @@ const struct usb_device_descriptor* usb_device_get_device_descriptor(struct usb_
char* usb_device_get_string(struct usb_device *device, int id)
{
char string[256];
__u16 buffer[128];
__u16 languages[128];
__u16 buffer[MAX_STRING_DESCRIPTOR_LENGTH / sizeof(__u16)];
__u16 languages[MAX_STRING_DESCRIPTOR_LENGTH / sizeof(__u16)];
int i, result;
int languageCount = 0;