2 em28xx-core.c - driver for Empia EM2800/EM2820/2840 USB video capture devices
4 Copyright (C) 2005 Ludovico Cavedon <cavedon@sssup.it>
5 Markus Rechberger <mrechberger@gmail.com>
6 Mauro Carvalho Chehab <mchehab@infradead.org>
7 Sascha Sommer <saschasommer@freenet.de>
9 This program is free software; you can redistribute it and/or modify
10 it under the terms of the GNU General Public License as published by
11 the Free Software Foundation; either version 2 of the License, or
12 (at your option) any later version.
14 This program is distributed in the hope that it will be useful,
15 but WITHOUT ANY WARRANTY; without even the implied warranty of
16 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 GNU General Public License for more details.
19 You should have received a copy of the GNU General Public License
20 along with this program; if not, write to the Free Software
21 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
24 #include <linux/init.h>
25 #include <linux/list.h>
26 #include <linux/module.h>
27 #include <linux/usb.h>
28 #include <linux/vmalloc.h>
32 /* #define ENABLE_DEBUG_ISOC_FRAMES */
34 static unsigned int core_debug = 0;
35 module_param(core_debug,int,0644);
36 MODULE_PARM_DESC(core_debug,"enable debug messages [core]");
38 #define em28xx_coredbg(fmt, arg...) do {\
40 printk(KERN_INFO "%s %s :"fmt, \
41 dev->name, __FUNCTION__ , ##arg); } while (0)
43 static unsigned int reg_debug = 0;
44 module_param(reg_debug,int,0644);
45 MODULE_PARM_DESC(reg_debug,"enable debug messages [URB reg]");
47 #define em28xx_regdbg(fmt, arg...) do {\
49 printk(KERN_INFO "%s %s :"fmt, \
50 dev->name, __FUNCTION__ , ##arg); } while (0)
52 static unsigned int isoc_debug = 0;
53 module_param(isoc_debug,int,0644);
54 MODULE_PARM_DESC(isoc_debug,"enable debug messages [isoc transfers]");
56 #define em28xx_isocdbg(fmt, arg...) do {\
58 printk(KERN_INFO "%s %s :"fmt, \
59 dev->name, __FUNCTION__ , ##arg); } while (0)
61 static int alt = EM28XX_PINOUT;
62 module_param(alt, int, 0644);
63 MODULE_PARM_DESC(alt, "alternate setting to use for video endpoint");
67 * em28xx_request_buffers()
68 * allocate a number of buffers
70 u32 em28xx_request_buffers(struct em28xx *dev, u32 count)
72 const size_t imagesize = PAGE_ALIGN(dev->frame_size); /*needs to be page aligned cause the buffers can be mapped individually! */
75 em28xx_coredbg("requested %i buffers with size %zi", count, imagesize);
76 if (count > EM28XX_NUM_FRAMES)
77 count = EM28XX_NUM_FRAMES;
79 dev->num_frames = count;
80 while (dev->num_frames > 0) {
81 if ((buff = vmalloc_32(dev->num_frames * imagesize))) {
82 memset(buff, 0, dev->num_frames * imagesize);
88 for (i = 0; i < dev->num_frames; i++) {
89 dev->frame[i].bufmem = buff + i * imagesize;
90 dev->frame[i].buf.index = i;
91 dev->frame[i].buf.m.offset = i * imagesize;
92 dev->frame[i].buf.length = dev->frame_size;
93 dev->frame[i].buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
94 dev->frame[i].buf.sequence = 0;
95 dev->frame[i].buf.field = V4L2_FIELD_NONE;
96 dev->frame[i].buf.memory = V4L2_MEMORY_MMAP;
97 dev->frame[i].buf.flags = 0;
99 return dev->num_frames;
103 * em28xx_queue_unusedframes()
104 * add all frames that are not currently in use to the inbuffer queue
106 void em28xx_queue_unusedframes(struct em28xx *dev)
108 unsigned long lock_flags;
111 for (i = 0; i < dev->num_frames; i++)
112 if (dev->frame[i].state == F_UNUSED) {
113 dev->frame[i].state = F_QUEUED;
114 spin_lock_irqsave(&dev->queue_lock, lock_flags);
115 list_add_tail(&dev->frame[i].frame, &dev->inqueue);
116 spin_unlock_irqrestore(&dev->queue_lock, lock_flags);
121 * em28xx_release_buffers()
124 void em28xx_release_buffers(struct em28xx *dev)
126 if (dev->num_frames) {
127 vfree(dev->frame[0].bufmem);
133 * em28xx_read_reg_req()
134 * reads data from the usb device specifying bRequest
136 int em28xx_read_reg_req_len(struct em28xx *dev, u8 req, u16 reg,
141 if (dev->state & DEV_DISCONNECTED)
144 em28xx_regdbg("req=%02x, reg=%02x ", req, reg);
146 ret = usb_control_msg(dev->udev, usb_rcvctrlpipe(dev->udev, 0), req,
147 USB_DIR_IN | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
148 0x0000, reg, buf, len, HZ);
151 printk(ret < 0 ? " failed!\n" : "%02x values: ", ret);
152 for (byte = 0; byte < len; byte++) {
153 printk(" %02x", buf[byte]);
162 * em28xx_read_reg_req()
163 * reads data from the usb device specifying bRequest
165 int em28xx_read_reg_req(struct em28xx *dev, u8 req, u16 reg)
170 if (dev->state & DEV_DISCONNECTED)
173 em28xx_regdbg("req=%02x, reg=%02x:", req, reg);
175 ret = usb_control_msg(dev->udev, usb_rcvctrlpipe(dev->udev, 0), req,
176 USB_DIR_IN | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
177 0x0000, reg, &val, 1, HZ);
180 printk(ret < 0 ? " failed!\n" : "%02x\n", val);
188 int em28xx_read_reg(struct em28xx *dev, u16 reg)
190 return em28xx_read_reg_req(dev, USB_REQ_GET_STATUS, reg);
194 * em28xx_write_regs_req()
195 * sends data to the usb device, specifying bRequest
197 int em28xx_write_regs_req(struct em28xx *dev, u8 req, u16 reg, char *buf,
202 /*usb_control_msg seems to expect a kmalloced buffer */
205 if (dev->state & DEV_DISCONNECTED)
208 bufs = kmalloc(len, GFP_KERNEL);
210 em28xx_regdbg("req=%02x reg=%02x:", req, reg);
214 for (i = 0; i < len; ++i)
215 printk (" %02x", (unsigned char)buf[i]);
221 memcpy(bufs, buf, len);
222 ret = usb_control_msg(dev->udev, usb_sndctrlpipe(dev->udev, 0), req,
223 USB_DIR_OUT | USB_TYPE_VENDOR | USB_RECIP_DEVICE,
224 0x0000, reg, bufs, len, HZ);
225 msleep(5); /* FIXME: magic number */
230 int em28xx_write_regs(struct em28xx *dev, u16 reg, char *buf, int len)
232 return em28xx_write_regs_req(dev, USB_REQ_GET_STATUS, reg, buf, len);
236 * em28xx_write_reg_bits()
237 * sets only some bits (specified by bitmask) of a register, by first reading
240 static int em28xx_write_reg_bits(struct em28xx *dev, u16 reg, u8 val,
245 if ((oldval = em28xx_read_reg(dev, reg)) < 0)
247 newval = (((u8) oldval) & ~bitmask) | (val & bitmask);
248 return em28xx_write_regs(dev, reg, &newval, 1);
252 * em28xx_write_ac97()
253 * write a 16 bit value to the specified AC97 address (LSB first!)
255 static int em28xx_write_ac97(struct em28xx *dev, u8 reg, u8 *val)
258 u8 addr = reg & 0x7f;
259 if ((ret = em28xx_write_regs(dev, AC97LSB_REG, val, 2)) < 0)
261 if ((ret = em28xx_write_regs(dev, AC97ADDR_REG, &addr, 1)) < 0)
263 if ((ret = em28xx_read_reg(dev, AC97BUSY_REG)) < 0)
265 else if (((u8) ret) & 0x01) {
266 em28xx_warn ("AC97 command still being executed: not handled properly!\n");
271 int em28xx_set_audio_source(struct em28xx *dev)
273 static char *enable = "\x08\x08";
274 static char *disable = "\x08\x88";
275 char *video = enable, *line = disable;
279 if (dev->is_em2800) {
281 input = EM2800_AUDIO_SRC_LINE;
283 input = EM2800_AUDIO_SRC_TUNER;
285 ret = em28xx_write_regs(dev, EM2800_AUDIOSRC_REG, &input, 1);
290 if (dev->has_msp34xx)
291 input = EM28XX_AUDIO_SRC_TUNER;
293 switch (dev->ctl_ainput) {
294 case EM28XX_AMUX_VIDEO:
295 input = EM28XX_AUDIO_SRC_TUNER;
297 case EM28XX_AMUX_LINE_IN:
298 input = EM28XX_AUDIO_SRC_LINE;
300 case EM28XX_AMUX_AC97_VIDEO:
301 input = EM28XX_AUDIO_SRC_LINE;
303 case EM28XX_AMUX_AC97_LINE_IN:
304 input = EM28XX_AUDIO_SRC_LINE;
311 ret = em28xx_write_reg_bits(dev, AUDIOSRC_REG, input, 0xc0);
315 /* Sets AC97 mixer registers
316 This is seems to be needed, even for non-ac97 configs
318 ret = em28xx_write_ac97(dev, VIDEO_AC97, video);
322 ret = em28xx_write_ac97(dev, LINE_IN_AC97, line);
327 int em28xx_audio_analog_set(struct em28xx *dev)
330 char s[2] = { 0x00, 0x00 };
333 s[0] |= 0x1f - dev->volume;
334 s[1] |= 0x1f - dev->volume;
338 ret = em28xx_write_ac97(dev, MASTER_AC97, s);
342 if (dev->has_12mhz_i2s)
348 ret = em28xx_write_reg_bits(dev, XCLK_REG, xclk, 0xa7);
353 /* Selects the proper audio input */
354 ret = em28xx_set_audio_source(dev);
358 EXPORT_SYMBOL_GPL(em28xx_audio_analog_set);
360 int em28xx_colorlevels_set_default(struct em28xx *dev)
362 em28xx_write_regs(dev, YGAIN_REG, "\x10", 1); /* contrast */
363 em28xx_write_regs(dev, YOFFSET_REG, "\x00", 1); /* brightness */
364 em28xx_write_regs(dev, UVGAIN_REG, "\x10", 1); /* saturation */
365 em28xx_write_regs(dev, UOFFSET_REG, "\x00", 1);
366 em28xx_write_regs(dev, VOFFSET_REG, "\x00", 1);
367 em28xx_write_regs(dev, SHARPNESS_REG, "\x00", 1);
369 em28xx_write_regs(dev, GAMMA_REG, "\x20", 1);
370 em28xx_write_regs(dev, RGAIN_REG, "\x20", 1);
371 em28xx_write_regs(dev, GGAIN_REG, "\x20", 1);
372 em28xx_write_regs(dev, BGAIN_REG, "\x20", 1);
373 em28xx_write_regs(dev, ROFFSET_REG, "\x00", 1);
374 em28xx_write_regs(dev, GOFFSET_REG, "\x00", 1);
375 return em28xx_write_regs(dev, BOFFSET_REG, "\x00", 1);
378 int em28xx_capture_start(struct em28xx *dev, int start)
381 /* FIXME: which is the best order? */
382 /* video registers are sampled by VREF */
383 if ((ret = em28xx_write_reg_bits(dev, USBSUSP_REG, start ? 0x10 : 0x00,
386 /* enable video capture */
387 return em28xx_write_regs(dev, VINENABLE_REG, start ? "\x67" : "\x27", 1);
390 int em28xx_outfmt_set_yuv422(struct em28xx *dev)
392 em28xx_write_regs(dev, OUTFMT_REG, "\x34", 1);
393 em28xx_write_regs(dev, VINMODE_REG, "\x10", 1);
394 return em28xx_write_regs(dev, VINCTRL_REG, "\x11", 1);
397 static int em28xx_accumulator_set(struct em28xx *dev, u8 xmin, u8 xmax,
400 em28xx_coredbg("em28xx Scale: (%d,%d)-(%d,%d)\n", xmin, ymin, xmax, ymax);
402 em28xx_write_regs(dev, XMIN_REG, &xmin, 1);
403 em28xx_write_regs(dev, XMAX_REG, &xmax, 1);
404 em28xx_write_regs(dev, YMIN_REG, &ymin, 1);
405 return em28xx_write_regs(dev, YMAX_REG, &ymax, 1);
408 static int em28xx_capture_area_set(struct em28xx *dev, u8 hstart, u8 vstart,
409 u16 width, u16 height)
413 u8 overflow = (height >> 7 & 0x02) | (width >> 8 & 0x01);
415 em28xx_coredbg("em28xx Area Set: (%d,%d)\n", (width | (overflow & 2) << 7),
416 (height | (overflow & 1) << 8));
418 em28xx_write_regs(dev, HSTART_REG, &hstart, 1);
419 em28xx_write_regs(dev, VSTART_REG, &vstart, 1);
420 em28xx_write_regs(dev, CWIDTH_REG, &cwidth, 1);
421 em28xx_write_regs(dev, CHEIGHT_REG, &cheight, 1);
422 return em28xx_write_regs(dev, OFLOW_REG, &overflow, 1);
425 static int em28xx_scaler_set(struct em28xx *dev, u16 h, u16 v)
428 /* the em2800 scaler only supports scaling down to 50% */
430 mode = (v ? 0x20 : 0x00) | (h ? 0x10 : 0x00);
435 em28xx_write_regs(dev, HSCALELOW_REG, (char *)buf, 2);
438 em28xx_write_regs(dev, VSCALELOW_REG, (char *)buf, 2);
439 /* it seems that both H and V scalers must be active to work correctly */
440 mode = (h || v)? 0x30: 0x00;
442 return em28xx_write_reg_bits(dev, COMPR_REG, mode, 0x30);
445 /* FIXME: this only function read values from dev */
446 int em28xx_resolution_set(struct em28xx *dev)
449 width = norm_maxw(dev);
450 height = norm_maxh(dev) >> 1;
452 em28xx_outfmt_set_yuv422(dev);
453 em28xx_accumulator_set(dev, 1, (width - 4) >> 2, 1, (height - 4) >> 2);
454 em28xx_capture_area_set(dev, 0, 0, width >> 2, height >> 2);
455 return em28xx_scaler_set(dev, dev->hscale, dev->vscale);
459 /******************* isoc transfer handling ****************************/
461 #ifdef ENABLE_DEBUG_ISOC_FRAMES
462 static void em28xx_isoc_dump(struct urb *urb)
468 printk(KERN_DEBUG "isocIrq: sf=%d np=%d ec=%x\n",
469 urb->start_frame, urb->number_of_packets,
471 for (i = 0; i < urb->number_of_packets; i++) {
473 urb->transfer_buffer +
474 urb->iso_frame_desc[i].offset;
475 int alen = urb->iso_frame_desc[i].actual_length;
477 if (buf[0] == 0x88) {
480 } else if (buf[0] == 0x22) {
482 "= l=%d nt=%d bpp=%d\n",
483 len - 4 * ntrans, ntrans,
484 ntrans == 0 ? 0 : len / ntrans);
488 printk(KERN_DEBUG "!\n");
490 printk(KERN_DEBUG " n=%d s=%d al=%d %x\n", i,
491 urb->iso_frame_desc[i].status,
492 urb->iso_frame_desc[i].actual_length,
494 *((unsigned char *)(urb->transfer_buffer +
495 urb->iso_frame_desc[i].
501 static inline int em28xx_isoc_video(struct em28xx *dev,struct em28xx_frame_t **f,
502 unsigned long *lock_flags, unsigned char buf)
505 if ((*f)->state == F_GRABBING) {
506 /*previous frame is incomplete */
507 if ((*f)->fieldbytesused < dev->field_size) {
508 (*f)->state = F_ERROR;
509 em28xx_isocdbg ("dropping incomplete bottom field (%i missing bytes)",
510 dev->field_size-(*f)->fieldbytesused);
512 (*f)->state = F_DONE;
513 (*f)->buf.bytesused = dev->frame_size;
516 if ((*f)->state == F_DONE || (*f)->state == F_ERROR) {
517 /* move current frame to outqueue and get next free buffer from inqueue */
518 spin_lock_irqsave(&dev-> queue_lock, *lock_flags);
519 list_move_tail(&(*f)->frame, &dev->outqueue);
520 if (!list_empty(&dev->inqueue))
521 (*f) = list_entry(dev-> inqueue.next,
522 struct em28xx_frame_t,frame);
525 spin_unlock_irqrestore(&dev->queue_lock,*lock_flags);
528 em28xx_isocdbg ("new frame but no buffer is free");
531 do_gettimeofday(&(*f)->buf.timestamp);
532 (*f)->buf.sequence = ++dev->frame_count;
533 (*f)->buf.field = V4L2_FIELD_INTERLACED;
534 (*f)->state = F_GRABBING;
535 (*f)->buf.bytesused = 0;
537 (*f)->fieldbytesused = 0;
539 /* acquiring bottom field */
540 if ((*f)->state == F_GRABBING) {
541 if (!(*f)->top_field) {
542 (*f)->state = F_ERROR;
543 em28xx_isocdbg ("unexpected begin of bottom field; discarding it");
544 } else if ((*f)-> fieldbytesused < dev->field_size - 172) {
545 (*f)->state = F_ERROR;
546 em28xx_isocdbg ("dropping incomplete top field (%i missing bytes)",
547 dev->field_size-(*f)->fieldbytesused);
550 (*f)->fieldbytesused = 0;
557 static inline void em28xx_isoc_video_copy(struct em28xx *dev,
558 struct em28xx_frame_t **f, unsigned char *buf, int len)
560 void *fieldstart, *startwrite, *startread;
561 int linesdone, currlinedone, offset, lencopy,remain;
563 if(dev->frame_size != (*f)->buf.length){
564 em28xx_err("frame_size %i and buf.length %i are different!!!\n",dev->frame_size,(*f)->buf.length);
568 if ((*f)->fieldbytesused + len > dev->field_size)
569 len =dev->field_size - (*f)->fieldbytesused;
571 if (buf[0] != 0x88 && buf[0] != 0x22) {
572 em28xx_isocdbg("frame is not complete\n");
581 fieldstart = (*f)->bufmem;
583 fieldstart = (*f)->bufmem + dev->bytesperline;
585 linesdone = (*f)->fieldbytesused / dev->bytesperline;
586 currlinedone = (*f)->fieldbytesused % dev->bytesperline;
587 offset = linesdone * dev->bytesperline * 2 + currlinedone;
588 startwrite = fieldstart + offset;
589 lencopy = dev->bytesperline - currlinedone;
590 lencopy = lencopy > remain ? remain : lencopy;
592 memcpy(startwrite, startread, lencopy);
596 startwrite += lencopy + dev->bytesperline;
597 startread += lencopy;
598 if (dev->bytesperline > remain)
601 lencopy = dev->bytesperline;
603 memcpy(startwrite, startread, lencopy);
607 (*f)->fieldbytesused += len;
612 * handles the incoming isoc urbs and fills the frames from our inqueue
614 static void em28xx_isocIrq(struct urb *urb)
616 struct em28xx *dev = urb->context;
618 struct em28xx_frame_t **f;
619 unsigned long lock_flags;
623 #ifdef ENABLE_DEBUG_ISOC_FRAMES
625 em28xx_isoc_dump(urb);
628 if (urb->status == -ENOENT)
631 f = &dev->frame_current;
633 if (dev->stream == STREAM_INTERRUPT) {
634 dev->stream = STREAM_OFF;
636 (*f)->state = F_QUEUED;
637 em28xx_isocdbg("stream interrupted");
638 wake_up_interruptible(&dev->wait_stream);
641 if ((dev->state & DEV_DISCONNECTED) || (dev->state & DEV_MISCONFIGURED))
644 if (dev->stream == STREAM_ON && !list_empty(&dev->inqueue)) {
646 (*f) = list_entry(dev->inqueue.next,
647 struct em28xx_frame_t, frame);
649 for (i = 0; i < urb->number_of_packets; i++) {
650 unsigned char *buf = urb->transfer_buffer +
651 urb->iso_frame_desc[i].offset;
652 int len = urb->iso_frame_desc[i].actual_length - 4;
654 if (urb->iso_frame_desc[i].status) {
655 em28xx_isocdbg("data error: [%d] len=%d, status=%d", i,
656 urb->iso_frame_desc[i].actual_length,
657 urb->iso_frame_desc[i].status);
658 if (urb->iso_frame_desc[i].status != -EPROTO)
661 if (urb->iso_frame_desc[i].actual_length <= 0) {
662 em28xx_isocdbg("packet %d is empty",i);
665 if (urb->iso_frame_desc[i].actual_length >
667 em28xx_isocdbg("packet bigger than packet size");
671 if (buf[0] == 0x22 && buf[1] == 0x5a) {
672 em28xx_isocdbg("Video frame, length=%i!",len);
674 if (em28xx_isoc_video(dev,f,&lock_flags,buf[2]))
676 } else if (buf[0]==0x33 && buf[1]==0x95 && buf[2]==0x00) {
677 em28xx_isocdbg("VBI HEADER!!!");
681 if ((*f)->state == F_GRABBING) {
682 em28xx_isoc_video_copy(dev,f,buf, len);
687 for (i = 0; i < urb->number_of_packets; i++) {
688 urb->iso_frame_desc[i].status = 0;
689 urb->iso_frame_desc[i].actual_length = 0;
693 if ((status = usb_submit_urb(urb, GFP_ATOMIC))) {
694 em28xx_errdev("resubmit of urb failed (error=%i)\n", status);
695 dev->state |= DEV_MISCONFIGURED;
697 wake_up_interruptible(&dev->wait_frame);
702 * em28xx_uninit_isoc()
703 * deallocates the buffers and urbs allocated during em28xx_init_iosc()
705 void em28xx_uninit_isoc(struct em28xx *dev)
709 for (i = 0; i < EM28XX_NUM_BUFS; i++) {
711 usb_kill_urb(dev->urb[i]);
712 if (dev->transfer_buffer[i]){
713 usb_buffer_free(dev->udev,(EM28XX_NUM_PACKETS*dev->max_pkt_size),dev->transfer_buffer[i],dev->urb[i]->transfer_dma);
715 usb_free_urb(dev->urb[i]);
718 dev->transfer_buffer[i] = NULL;
720 em28xx_capture_start(dev, 0);
725 * allocates transfer buffers and submits the urbs for isoc transfer
727 int em28xx_init_isoc(struct em28xx *dev)
729 /* change interface to 3 which allows the biggest packet sizes */
731 const int sb_size = EM28XX_NUM_PACKETS * dev->max_pkt_size;
733 /* reset streaming vars */
734 dev->frame_current = NULL;
735 dev->frame_count = 0;
738 for (i = 0; i < EM28XX_NUM_BUFS; i++) {
741 /* allocate transfer buffer */
742 urb = usb_alloc_urb(EM28XX_NUM_PACKETS, GFP_KERNEL);
744 em28xx_errdev("cannot alloc urb %i\n", i);
745 em28xx_uninit_isoc(dev);
748 dev->transfer_buffer[i] = usb_buffer_alloc(dev->udev, sb_size, GFP_KERNEL,&urb->transfer_dma);
749 if (!dev->transfer_buffer[i]) {
751 ("unable to allocate %i bytes for transfer buffer %i\n",
753 em28xx_uninit_isoc(dev);
757 memset(dev->transfer_buffer[i], 0, sb_size);
758 urb->dev = dev->udev;
760 urb->pipe = usb_rcvisocpipe(dev->udev, 0x82);
761 urb->transfer_flags = URB_ISO_ASAP;
763 urb->transfer_buffer = dev->transfer_buffer[i];
764 urb->complete = em28xx_isocIrq;
765 urb->number_of_packets = EM28XX_NUM_PACKETS;
766 urb->transfer_buffer_length = sb_size;
767 for (j = k = 0; j < EM28XX_NUM_PACKETS;
768 j++, k += dev->max_pkt_size) {
769 urb->iso_frame_desc[j].offset = k;
770 urb->iso_frame_desc[j].length =
777 for (i = 0; i < EM28XX_NUM_BUFS; i++) {
778 errCode = usb_submit_urb(dev->urb[i], GFP_KERNEL);
780 em28xx_errdev("submit of urb %i failed (error=%i)\n", i,
782 em28xx_uninit_isoc(dev);
790 int em28xx_set_alternate(struct em28xx *dev)
792 int errCode, prev_alt = dev->alt;
796 for(i=0;i< dev->num_alt; i++)
797 if(dev->alt_max_pkt_size[i]>dev->alt_max_pkt_size[dev->alt])
801 if (dev->alt != prev_alt) {
802 dev->max_pkt_size = dev->alt_max_pkt_size[dev->alt];
803 em28xx_coredbg("setting alternate %d with wMaxPacketSize=%u\n", dev->alt,
805 errCode = usb_set_interface(dev->udev, 0, dev->alt);
807 em28xx_errdev ("cannot change alternate number to %d (error=%i)\n",