OpenCloudOS-Kernel/drivers/media/video/em28xx/em28xx-core.c

736 lines
20 KiB
C

/*
em28xx-core.c - driver for Empia EM2800/EM2820/2840 USB video capture devices
Copyright (C) 2005 Ludovico Cavedon <cavedon@sssup.it>
Markus Rechberger <mrechberger@gmail.com>
Mauro Carvalho Chehab <mchehab@infradead.org>
Sascha Sommer <saschasommer@freenet.de>
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
#include <linux/init.h>
#include <linux/list.h>
#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/usb.h>
#include <linux/vmalloc.h>
#include "em28xx.h"
/* #define ENABLE_DEBUG_ISOC_FRAMES */
static unsigned int core_debug = 0;
module_param(core_debug,int,0644);
MODULE_PARM_DESC(core_debug,"enable debug messages [core]");
#define em28xx_coredbg(fmt, arg...) do {\
if (core_debug) \
printk(KERN_INFO "%s %s :"fmt, \
dev->name, __FUNCTION__ , ##arg); } while (0)
static unsigned int reg_debug = 0;
module_param(reg_debug,int,0644);
MODULE_PARM_DESC(reg_debug,"enable debug messages [URB reg]");
#define em28xx_regdbg(fmt, arg...) do {\
if (reg_debug) \
printk(KERN_INFO "%s %s :"fmt, \
dev->name, __FUNCTION__ , ##arg); } while (0)
static unsigned int isoc_debug = 0;
module_param(isoc_debug,int,0644);
MODULE_PARM_DESC(isoc_debug,"enable debug messages [isoc transfers]");
#define em28xx_isocdbg(fmt, arg...) do {\
if (isoc_debug) \
printk(KERN_INFO "%s %s :"fmt, \
dev->name, __FUNCTION__ , ##arg); } while (0)
static int alt = EM28XX_PINOUT;
module_param(alt, int, 0644);
MODULE_PARM_DESC(alt, "alternate setting to use for video endpoint");
/*
* em28xx_request_buffers()
* allocate a number of buffers
*/
u32 em28xx_request_buffers(struct em28xx *dev, u32 count)
{
const size_t imagesize = PAGE_ALIGN(dev->frame_size); /*needs to be page aligned cause the buffers can be mapped individually! */
void *buff = NULL;
u32 i;
em28xx_coredbg("requested %i buffers with size %zi", count, imagesize);
if (count > EM28XX_NUM_FRAMES)
count = EM28XX_NUM_FRAMES;
dev->num_frames = count;
while (dev->num_frames > 0) {
if ((buff = vmalloc_32(dev->num_frames * imagesize))) {
memset(buff, 0, dev->num_frames * imagesize);
break;
}
dev->num_frames--;
}
for (i = 0; i < dev->num_frames; i++) {
dev->frame[i].bufmem = buff + i * imagesize;
dev->frame[i].buf.index = i;
dev->frame[i].buf.m.offset = i * imagesize;
dev->frame[i].buf.length = dev->frame_size;
dev->frame[i].buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
dev->frame[i].buf.sequence = 0;
dev->frame[i].buf.field = V4L2_FIELD_NONE;
dev->frame[i].buf.memory = V4L2_MEMORY_MMAP;
dev->frame[i].buf.flags = 0;
}
return dev->num_frames;
}
/*
* em28xx_queue_unusedframes()
* add all frames that are not currently in use to the inbuffer queue
*/
void em28xx_queue_unusedframes(struct em28xx *dev)
{
unsigned long lock_flags;
u32 i;
for (i = 0; i < dev->num_frames; i++)
if (dev->frame[i].state == F_UNUSED) {
dev->frame[i].state = F_QUEUED;
spin_lock_irqsave(&dev->queue_lock, lock_flags);
list_add_tail(&dev->frame[i].frame, &dev->inqueue);
spin_unlock_irqrestore(&dev->queue_lock, lock_flags);
}
}
/*
* em28xx_release_buffers()
* free frame buffers
*/
void em28xx_release_buffers(struct em28xx *dev)
{
if (dev->num_frames) {
vfree(dev->frame[0].bufmem);
dev->num_frames = 0;
}
}
/*
* em28xx_read_reg_req()
* reads data from the usb device specifying bRequest
*/
int em28xx_read_reg_req_len(struct em28xx *dev, u8 req, u16 reg,
char *buf, int len)
{
int ret, byte;
if (dev->state & DEV_DISCONNECTED)
return(-ENODEV);
em28xx_regdbg("req=%02x, reg=%02x ", req, reg);
ret = usb_control_msg(dev->udev, usb_rcvctrlpipe(dev->udev, 0), req,
USB_DIR_IN | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
0x0000, reg, buf, len, HZ);
if (reg_debug){
printk(ret < 0 ? " failed!\n" : "%02x values: ", ret);
for (byte = 0; byte < len; byte++) {
printk(" %02x", buf[byte]);
}
printk("\n");
}
return ret;
}
/*
* em28xx_read_reg_req()
* reads data from the usb device specifying bRequest
*/
int em28xx_read_reg_req(struct em28xx *dev, u8 req, u16 reg)
{
u8 val;
int ret;
if (dev->state & DEV_DISCONNECTED)
return(-ENODEV);
em28xx_regdbg("req=%02x, reg=%02x:", req, reg);
ret = usb_control_msg(dev->udev, usb_rcvctrlpipe(dev->udev, 0), req,
USB_DIR_IN | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
0x0000, reg, &val, 1, HZ);
if (reg_debug)
printk(ret < 0 ? " failed!\n" : "%02x\n", val);
if (ret < 0)
return ret;
return val;
}
int em28xx_read_reg(struct em28xx *dev, u16 reg)
{
return em28xx_read_reg_req(dev, USB_REQ_GET_STATUS, reg);
}
/*
* em28xx_write_regs_req()
* sends data to the usb device, specifying bRequest
*/
int em28xx_write_regs_req(struct em28xx *dev, u8 req, u16 reg, char *buf,
int len)
{
int ret;
/*usb_control_msg seems to expect a kmalloced buffer */
unsigned char *bufs;
if (dev->state & DEV_DISCONNECTED)
return(-ENODEV);
bufs = kmalloc(len, GFP_KERNEL);
em28xx_regdbg("req=%02x reg=%02x:", req, reg);
if (reg_debug) {
int i;
for (i = 0; i < len; ++i)
printk (" %02x", (unsigned char)buf[i]);
printk ("\n");
}
if (!bufs)
return -ENOMEM;
memcpy(bufs, buf, len);
ret = usb_control_msg(dev->udev, usb_sndctrlpipe(dev->udev, 0), req,
USB_DIR_OUT | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
0x0000, reg, bufs, len, HZ);
msleep(5); /* FIXME: magic number */
kfree(bufs);
return ret;
}
int em28xx_write_regs(struct em28xx *dev, u16 reg, char *buf, int len)
{
return em28xx_write_regs_req(dev, USB_REQ_GET_STATUS, reg, buf, len);
}
/*
* em28xx_write_reg_bits()
* sets only some bits (specified by bitmask) of a register, by first reading
* the actual value
*/
int em28xx_write_reg_bits(struct em28xx *dev, u16 reg, u8 val,
u8 bitmask)
{
int oldval;
u8 newval;
if ((oldval = em28xx_read_reg(dev, reg)) < 0)
return oldval;
newval = (((u8) oldval) & ~bitmask) | (val & bitmask);
return em28xx_write_regs(dev, reg, &newval, 1);
}
/*
* em28xx_write_ac97()
* write a 16 bit value to the specified AC97 address (LSB first!)
*/
int em28xx_write_ac97(struct em28xx *dev, u8 reg, u8 * val)
{
int ret;
u8 addr = reg & 0x7f;
if ((ret = em28xx_write_regs(dev, AC97LSB_REG, val, 2)) < 0)
return ret;
if ((ret = em28xx_write_regs(dev, AC97ADDR_REG, &addr, 1)) < 0)
return ret;
if ((ret = em28xx_read_reg(dev, AC97BUSY_REG)) < 0)
return ret;
else if (((u8) ret) & 0x01) {
em28xx_warn ("AC97 command still being executed: not handled properly!\n");
}
return 0;
}
int em28xx_audio_analog_set(struct em28xx *dev)
{
char s[2] = { 0x00, 0x00 };
s[0] |= 0x1f - dev->volume;
s[1] |= 0x1f - dev->volume;
if (dev->mute)
s[1] |= 0x80;
return em28xx_write_ac97(dev, MASTER_AC97, s);
}
int em28xx_colorlevels_set_default(struct em28xx *dev)
{
em28xx_write_regs(dev, YGAIN_REG, "\x10", 1); /* contrast */
em28xx_write_regs(dev, YOFFSET_REG, "\x00", 1); /* brightness */
em28xx_write_regs(dev, UVGAIN_REG, "\x10", 1); /* saturation */
em28xx_write_regs(dev, UOFFSET_REG, "\x00", 1);
em28xx_write_regs(dev, VOFFSET_REG, "\x00", 1);
em28xx_write_regs(dev, SHARPNESS_REG, "\x00", 1);
em28xx_write_regs(dev, GAMMA_REG, "\x20", 1);
em28xx_write_regs(dev, RGAIN_REG, "\x20", 1);
em28xx_write_regs(dev, GGAIN_REG, "\x20", 1);
em28xx_write_regs(dev, BGAIN_REG, "\x20", 1);
em28xx_write_regs(dev, ROFFSET_REG, "\x00", 1);
em28xx_write_regs(dev, GOFFSET_REG, "\x00", 1);
return em28xx_write_regs(dev, BOFFSET_REG, "\x00", 1);
}
int em28xx_capture_start(struct em28xx *dev, int start)
{
int ret;
/* FIXME: which is the best order? */
/* video registers are sampled by VREF */
if ((ret = em28xx_write_reg_bits(dev, USBSUSP_REG, start ? 0x10 : 0x00,
0x10)) < 0)
return ret;
/* enable video capture */
return em28xx_write_regs(dev, VINENABLE_REG, start ? "\x67" : "\x27", 1);
}
int em28xx_outfmt_set_yuv422(struct em28xx *dev)
{
em28xx_write_regs(dev, OUTFMT_REG, "\x34", 1);
em28xx_write_regs(dev, VINMODE_REG, "\x10", 1);
return em28xx_write_regs(dev, VINCTRL_REG, "\x11", 1);
}
static int em28xx_accumulator_set(struct em28xx *dev, u8 xmin, u8 xmax,
u8 ymin, u8 ymax)
{
em28xx_coredbg("em28xx Scale: (%d,%d)-(%d,%d)\n", xmin, ymin, xmax, ymax);
em28xx_write_regs(dev, XMIN_REG, &xmin, 1);
em28xx_write_regs(dev, XMAX_REG, &xmax, 1);
em28xx_write_regs(dev, YMIN_REG, &ymin, 1);
return em28xx_write_regs(dev, YMAX_REG, &ymax, 1);
}
static int em28xx_capture_area_set(struct em28xx *dev, u8 hstart, u8 vstart,
u16 width, u16 height)
{
u8 cwidth = width;
u8 cheight = height;
u8 overflow = (height >> 7 & 0x02) | (width >> 8 & 0x01);
em28xx_coredbg("em28xx Area Set: (%d,%d)\n", (width | (overflow & 2) << 7),
(height | (overflow & 1) << 8));
em28xx_write_regs(dev, HSTART_REG, &hstart, 1);
em28xx_write_regs(dev, VSTART_REG, &vstart, 1);
em28xx_write_regs(dev, CWIDTH_REG, &cwidth, 1);
em28xx_write_regs(dev, CHEIGHT_REG, &cheight, 1);
return em28xx_write_regs(dev, OFLOW_REG, &overflow, 1);
}
static int em28xx_scaler_set(struct em28xx *dev, u16 h, u16 v)
{
u8 mode;
/* the em2800 scaler only supports scaling down to 50% */
if(dev->is_em2800)
mode = (v ? 0x20 : 0x00) | (h ? 0x10 : 0x00);
else {
u8 buf[2];
buf[0] = h;
buf[1] = h >> 8;
em28xx_write_regs(dev, HSCALELOW_REG, (char *)buf, 2);
buf[0] = v;
buf[1] = v >> 8;
em28xx_write_regs(dev, VSCALELOW_REG, (char *)buf, 2);
/* it seems that both H and V scalers must be active to work correctly */
mode = (h || v)? 0x30: 0x00;
}
return em28xx_write_reg_bits(dev, COMPR_REG, mode, 0x30);
}
/* FIXME: this only function read values from dev */
int em28xx_resolution_set(struct em28xx *dev)
{
int width, height;
width = norm_maxw(dev);
height = norm_maxh(dev) >> 1;
em28xx_outfmt_set_yuv422(dev);
em28xx_accumulator_set(dev, 1, (width - 4) >> 2, 1, (height - 4) >> 2);
em28xx_capture_area_set(dev, 0, 0, width >> 2, height >> 2);
return em28xx_scaler_set(dev, dev->hscale, dev->vscale);
}
/******************* isoc transfer handling ****************************/
#ifdef ENABLE_DEBUG_ISOC_FRAMES
static void em28xx_isoc_dump(struct urb *urb)
{
int len = 0;
int ntrans = 0;
int i;
printk(KERN_DEBUG "isocIrq: sf=%d np=%d ec=%x\n",
urb->start_frame, urb->number_of_packets,
urb->error_count);
for (i = 0; i < urb->number_of_packets; i++) {
unsigned char *buf =
urb->transfer_buffer +
urb->iso_frame_desc[i].offset;
int alen = urb->iso_frame_desc[i].actual_length;
if (alen > 0) {
if (buf[0] == 0x88) {
ntrans++;
len += alen;
} else if (buf[0] == 0x22) {
printk(KERN_DEBUG
"= l=%d nt=%d bpp=%d\n",
len - 4 * ntrans, ntrans,
ntrans == 0 ? 0 : len / ntrans);
ntrans = 1;
len = alen;
} else
printk(KERN_DEBUG "!\n");
}
printk(KERN_DEBUG " n=%d s=%d al=%d %x\n", i,
urb->iso_frame_desc[i].status,
urb->iso_frame_desc[i].actual_length,
(unsigned int)
*((unsigned char *)(urb->transfer_buffer +
urb->iso_frame_desc[i].
offset)));
}
}
#endif
static inline int em28xx_isoc_video(struct em28xx *dev,struct em28xx_frame_t **f,
unsigned long *lock_flags, unsigned char buf)
{
if (!(buf & 0x01)) {
if ((*f)->state == F_GRABBING) {
/*previous frame is incomplete */
if ((*f)->fieldbytesused < dev->field_size) {
(*f)->state = F_ERROR;
em28xx_isocdbg ("dropping incomplete bottom field (%i missing bytes)",
dev->field_size-(*f)->fieldbytesused);
} else {
(*f)->state = F_DONE;
(*f)->buf.bytesused = dev->frame_size;
}
}
if ((*f)->state == F_DONE || (*f)->state == F_ERROR) {
/* move current frame to outqueue and get next free buffer from inqueue */
spin_lock_irqsave(&dev-> queue_lock, *lock_flags);
list_move_tail(&(*f)->frame, &dev->outqueue);
if (!list_empty(&dev->inqueue))
(*f) = list_entry(dev-> inqueue.next,
struct em28xx_frame_t,frame);
else
(*f) = NULL;
spin_unlock_irqrestore(&dev->queue_lock,*lock_flags);
}
if (!(*f)) {
em28xx_isocdbg ("new frame but no buffer is free");
return -1;
}
do_gettimeofday(&(*f)->buf.timestamp);
(*f)->buf.sequence = ++dev->frame_count;
(*f)->buf.field = V4L2_FIELD_INTERLACED;
(*f)->state = F_GRABBING;
(*f)->buf.bytesused = 0;
(*f)->top_field = 1;
(*f)->fieldbytesused = 0;
} else {
/* acquiring bottom field */
if ((*f)->state == F_GRABBING) {
if (!(*f)->top_field) {
(*f)->state = F_ERROR;
em28xx_isocdbg ("unexpected begin of bottom field; discarding it");
} else if ((*f)-> fieldbytesused < dev->field_size - 172) {
(*f)->state = F_ERROR;
em28xx_isocdbg ("dropping incomplete top field (%i missing bytes)",
dev->field_size-(*f)->fieldbytesused);
} else {
(*f)->top_field = 0;
(*f)->fieldbytesused = 0;
}
}
}
return (0);
}
static inline void em28xx_isoc_video_copy(struct em28xx *dev,
struct em28xx_frame_t **f, unsigned char *buf, int len)
{
void *fieldstart, *startwrite, *startread;
int linesdone, currlinedone, offset, lencopy,remain;
if(dev->frame_size != (*f)->buf.length){
em28xx_err("frame_size %i and buf.length %i are different!!!\n",dev->frame_size,(*f)->buf.length);
return;
}
if ((*f)->fieldbytesused + len > dev->field_size)
len =dev->field_size - (*f)->fieldbytesused;
if (buf[0] != 0x88 && buf[0] != 0x22) {
em28xx_isocdbg("frame is not complete\n");
startread = buf;
len+=4;
} else
startread = buf + 4;
remain = len;
if ((*f)->top_field)
fieldstart = (*f)->bufmem;
else
fieldstart = (*f)->bufmem + dev->bytesperline;
linesdone = (*f)->fieldbytesused / dev->bytesperline;
currlinedone = (*f)->fieldbytesused % dev->bytesperline;
offset = linesdone * dev->bytesperline * 2 + currlinedone;
startwrite = fieldstart + offset;
lencopy = dev->bytesperline - currlinedone;
lencopy = lencopy > remain ? remain : lencopy;
memcpy(startwrite, startread, lencopy);
remain -= lencopy;
while (remain > 0) {
startwrite += lencopy + dev->bytesperline;
startread += lencopy;
if (dev->bytesperline > remain)
lencopy = remain;
else
lencopy = dev->bytesperline;
memcpy(startwrite, startread, lencopy);
remain -= lencopy;
}
(*f)->fieldbytesused += len;
}
/*
* em28xx_isoIrq()
* handles the incoming isoc urbs and fills the frames from our inqueue
*/
static void em28xx_isocIrq(struct urb *urb)
{
struct em28xx *dev = urb->context;
int i, status;
struct em28xx_frame_t **f;
unsigned long lock_flags;
if (!dev)
return;
#ifdef ENABLE_DEBUG_ISOC_FRAMES
if (isoc_debug>1)
em28xx_isoc_dump(urb);
#endif
if (urb->status == -ENOENT)
return;
f = &dev->frame_current;
if (dev->stream == STREAM_INTERRUPT) {
dev->stream = STREAM_OFF;
if ((*f))
(*f)->state = F_QUEUED;
em28xx_isocdbg("stream interrupted");
wake_up_interruptible(&dev->wait_stream);
}
if ((dev->state & DEV_DISCONNECTED) || (dev->state & DEV_MISCONFIGURED))
return;
if (dev->stream == STREAM_ON && !list_empty(&dev->inqueue)) {
if (!(*f))
(*f) = list_entry(dev->inqueue.next,
struct em28xx_frame_t, frame);
for (i = 0; i < urb->number_of_packets; i++) {
unsigned char *buf = urb->transfer_buffer +
urb->iso_frame_desc[i].offset;
int len = urb->iso_frame_desc[i].actual_length - 4;
if (urb->iso_frame_desc[i].status) {
em28xx_isocdbg("data error: [%d] len=%d, status=%d", i,
urb->iso_frame_desc[i].actual_length,
urb->iso_frame_desc[i].status);
if (urb->iso_frame_desc[i].status != -EPROTO)
continue;
}
if (urb->iso_frame_desc[i].actual_length <= 0) {
em28xx_isocdbg("packet %d is empty",i);
continue;
}
if (urb->iso_frame_desc[i].actual_length >
dev->max_pkt_size) {
em28xx_isocdbg("packet bigger than packet size");
continue;
}
/*new frame */
if (buf[0] == 0x22 && buf[1] == 0x5a) {
em28xx_isocdbg("Video frame, length=%i!",len);
if (em28xx_isoc_video(dev,f,&lock_flags,buf[2]))
break;
} else if (buf[0]==0x33 && buf[1]==0x95 && buf[2]==0x00) {
em28xx_isocdbg("VBI HEADER!!!");
}
/* actual copying */
if ((*f)->state == F_GRABBING) {
em28xx_isoc_video_copy(dev,f,buf, len);
}
}
}
for (i = 0; i < urb->number_of_packets; i++) {
urb->iso_frame_desc[i].status = 0;
urb->iso_frame_desc[i].actual_length = 0;
}
urb->status = 0;
if ((status = usb_submit_urb(urb, GFP_ATOMIC))) {
em28xx_errdev("resubmit of urb failed (error=%i)\n", status);
dev->state |= DEV_MISCONFIGURED;
}
wake_up_interruptible(&dev->wait_frame);
return;
}
/*
* em28xx_uninit_isoc()
* deallocates the buffers and urbs allocated during em28xx_init_iosc()
*/
void em28xx_uninit_isoc(struct em28xx *dev)
{
int i;
for (i = 0; i < EM28XX_NUM_BUFS; i++) {
if (dev->urb[i]) {
usb_kill_urb(dev->urb[i]);
if (dev->transfer_buffer[i]){
usb_buffer_free(dev->udev,(EM28XX_NUM_PACKETS*dev->max_pkt_size),dev->transfer_buffer[i],dev->urb[i]->transfer_dma);
}
usb_free_urb(dev->urb[i]);
}
dev->urb[i] = NULL;
dev->transfer_buffer[i] = NULL;
}
em28xx_capture_start(dev, 0);
}
/*
* em28xx_init_isoc()
* allocates transfer buffers and submits the urbs for isoc transfer
*/
int em28xx_init_isoc(struct em28xx *dev)
{
/* change interface to 3 which allowes the biggest packet sizes */
int i, errCode;
const int sb_size = EM28XX_NUM_PACKETS * dev->max_pkt_size;
/* reset streaming vars */
dev->frame_current = NULL;
dev->frame_count = 0;
/* allocate urbs */
for (i = 0; i < EM28XX_NUM_BUFS; i++) {
struct urb *urb;
int j, k;
/* allocate transfer buffer */
urb = usb_alloc_urb(EM28XX_NUM_PACKETS, GFP_KERNEL);
if (!urb){
em28xx_errdev("cannot alloc urb %i\n", i);
em28xx_uninit_isoc(dev);
return -ENOMEM;
}
dev->transfer_buffer[i] = usb_buffer_alloc(dev->udev, sb_size, GFP_KERNEL,&urb->transfer_dma);
if (!dev->transfer_buffer[i]) {
em28xx_errdev
("unable to allocate %i bytes for transfer buffer %i\n",
sb_size, i);
em28xx_uninit_isoc(dev);
return -ENOMEM;
}
memset(dev->transfer_buffer[i], 0, sb_size);
urb->dev = dev->udev;
urb->context = dev;
urb->pipe = usb_rcvisocpipe(dev->udev, 0x82);
urb->transfer_flags = URB_ISO_ASAP;
urb->interval = 1;
urb->transfer_buffer = dev->transfer_buffer[i];
urb->complete = em28xx_isocIrq;
urb->number_of_packets = EM28XX_NUM_PACKETS;
urb->transfer_buffer_length = sb_size;
for (j = k = 0; j < EM28XX_NUM_PACKETS;
j++, k += dev->max_pkt_size) {
urb->iso_frame_desc[j].offset = k;
urb->iso_frame_desc[j].length =
dev->max_pkt_size;
}
dev->urb[i] = urb;
}
/* submit urbs */
for (i = 0; i < EM28XX_NUM_BUFS; i++) {
errCode = usb_submit_urb(dev->urb[i], GFP_KERNEL);
if (errCode) {
em28xx_errdev("submit of urb %i failed (error=%i)\n", i,
errCode);
em28xx_uninit_isoc(dev);
return errCode;
}
}
return 0;
}
int em28xx_set_alternate(struct em28xx *dev)
{
int errCode, prev_alt = dev->alt;
dev->alt = alt;
if (dev->alt == 0) {
int i;
for(i=0;i< dev->num_alt; i++)
if(dev->alt_max_pkt_size[i]>dev->alt_max_pkt_size[dev->alt])
dev->alt=i;
}
if (dev->alt != prev_alt) {
dev->max_pkt_size = dev->alt_max_pkt_size[dev->alt];
em28xx_coredbg("setting alternate %d with wMaxPacketSize=%u\n", dev->alt,
dev->max_pkt_size);
errCode = usb_set_interface(dev->udev, 0, dev->alt);
if (errCode < 0) {
em28xx_errdev ("cannot change alternate number to %d (error=%i)\n",
dev->alt, errCode);
return errCode;
}
}
return 0;
}