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https://github.com/torvalds/linux
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V4L/DVB: ir-rc5-decoder: fix state machine
Reimplement the RC-5 decoder state machine. Code is now clear, and works properly. It is also simpler than the previous implementations. Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>
This commit is contained in:
Mauro Carvalho Chehab
parent
7f20d32d44
commit
9b09df51b8
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@ -15,19 +15,17 @@
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/*
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* This code only handles 14 bits RC-5 protocols. There are other variants
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* that use a different number of bits. This is currently unsupported
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* It considers a carrier of 36 kHz, with a total of 14 bits, where
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* the first two bits are start bits, and a third one is a filing bit
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*/
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#include <media/ir-core.h>
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static unsigned int ir_rc5_remote_gap = 888888;
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#define RC5_NBITS 14
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#define RC5_HALFBIT 888888 /* ns */
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#define RC5_BIT (RC5_HALFBIT * 2)
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#define RC5_DURATION (RC5_BIT * RC5_NBITS)
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#define is_rc5_halfbit(nsec) ((ev->delta.tv_nsec >= RC5_HALFBIT / 2) && \
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(ev->delta.tv_nsec < RC5_HALFBIT + RC5_HALFBIT / 2))
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#define n_half(nsec) ((ev->delta.tv_nsec + RC5_HALFBIT / 2) / RC5_HALFBIT)
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#define RC5_BIT (ir_rc5_remote_gap * 2)
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#define RC5_DURATION (ir_rc5_remote_gap * RC5_NBITS)
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/* Used to register rc5_decoder clients */
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static LIST_HEAD(decoder_list);
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@ -35,19 +33,8 @@ static spinlock_t decoder_lock;
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enum rc5_state {
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STATE_INACTIVE,
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STATE_START2_SPACE,
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STATE_START2_MARK,
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STATE_MARKSPACE,
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STATE_TRAILER_MARK,
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};
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static char *st_name[] = {
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"Inactive",
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"start2 sapce",
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"start2 mark",
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"mark",
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"space",
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"trailer"
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STATE_TRAILER,
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};
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struct rc5_code {
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@ -63,8 +50,7 @@ struct decoder_data {
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/* State machine control */
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enum rc5_state state;
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struct rc5_code rc5_code;
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unsigned n_half;
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unsigned count;
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unsigned code, elapsed, last_bit, last_code;
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};
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@ -147,7 +133,7 @@ static int ir_rc5_decode(struct input_dev *input_dev,
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{
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struct decoder_data *data;
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struct ir_input_dev *ir_dev = input_get_drvdata(input_dev);
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int bit, last_bit, n_half;
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int is_pulse, scancode, delta, toggle;
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data = get_decoder_data(ir_dev);
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if (!data)
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@ -156,122 +142,79 @@ static int ir_rc5_decode(struct input_dev *input_dev,
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if (!data->enabled)
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return 0;
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/* Except for the initial event, what matters is the previous bit */
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bit = (ev->type & IR_PULSE) ? 1 : 0;
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delta = DIV_ROUND_CLOSEST(ev->delta.tv_nsec, ir_rc5_remote_gap);
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last_bit = !bit;
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/* Discards spurious space last_bits when inactive */
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/* The duration time refers to the last bit time */
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is_pulse = (ev->type & IR_PULSE) ? 1 : 0;
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/* Very long delays are considered as start events */
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if (ev->delta.tv_nsec > RC5_DURATION + RC5_HALFBIT / 2)
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data->state = STATE_INACTIVE;
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if (ev->type & IR_START_EVENT)
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if (delta > RC5_DURATION || (ev->type & IR_START_EVENT))
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data->state = STATE_INACTIVE;
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switch (data->state) {
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case STATE_INACTIVE:
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IR_dprintk(1, "currently inative. Received bit (%s) @%luus\n",
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last_bit ? "pulse" : "space",
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(ev->delta.tv_nsec + 500) / 1000);
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IR_dprintk(2, "currently inative. Start bit (%s) @%uus\n",
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is_pulse ? "pulse" : "space",
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(unsigned)(ev->delta.tv_nsec + 500) / 1000);
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/* Discards the initial start space */
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if (bit)
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return 0;
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data->count = 0;
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data->n_half = 0;
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memset (&data->rc5_code, 0, sizeof(data->rc5_code));
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data->state = STATE_START2_SPACE;
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return 0;
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case STATE_START2_SPACE:
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if (last_bit)
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if (!is_pulse)
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goto err;
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if (!is_rc5_halfbit(ev->delta.tv_nsec))
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goto err;
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data->state = STATE_START2_MARK;
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return 0;
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case STATE_START2_MARK:
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if (!last_bit)
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goto err;
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if (!is_rc5_halfbit(ev->delta.tv_nsec))
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goto err;
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data->code = 1;
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data->last_bit = 1;
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data->elapsed = 0;
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memset(&data->rc5_code, 0, sizeof(data->rc5_code));
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data->state = STATE_MARKSPACE;
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return 0;
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case STATE_MARKSPACE:
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n_half = n_half(ev->delta.tv_nsec);
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if (n_half < 1 || n_half > 3) {
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IR_dprintk(1, "Decode failed at %d-th bit (%s) @%luus\n",
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data->count,
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last_bit ? "pulse" : "space",
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(ev->delta.tv_nsec + 500) / 1000);
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printk("%d halves\n", n_half);
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goto err2;
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}
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data->n_half += n_half;
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if (delta != 1)
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data->last_bit = data->last_bit ? 0 : 1;
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if (!last_bit)
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data->elapsed += delta;
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if ((data->elapsed % 2) == 1)
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return 0;
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/* Got one complete mark/space cycle */
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data->code <<= 1;
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data->code |= data->last_bit;
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bit = ((data->count + 1) * 2)/ data->n_half;
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/* Fill the 2 unused bits at the command with 0 */
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if (data->elapsed / 2 == 6)
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data->code <<= 2;
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printk("%d halves, %d bits\n", n_half, bit);
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if (data->elapsed >= (RC5_NBITS - 1) * 2) {
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scancode = data->code;
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#if 1 /* SANITY check - while testing the decoder */
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if (bit > 1) {
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IR_dprintk(1, "Decoder HAS failed at %d-th bit (%s) @%luus\n",
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data->count,
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last_bit ? "pulse" : "space",
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(ev->delta.tv_nsec + 500) / 1000);
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goto err2;
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}
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#endif
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/* Ok, we've got a valid bit. proccess it */
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if (bit) {
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int shift = data->count;
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/*
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* RC-5 transmit bytes on this temporal order:
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* address | not address | command | not command
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*/
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if (shift < 8) {
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data->rc5_code.address |= 1 << shift;
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} else {
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data->rc5_code.command |= 1 << (shift - 8);
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/* Check for the start bits */
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if ((scancode & 0xc000) != 0xc000) {
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IR_dprintk(1, "Code 0x%04x doesn't have two start bits. It is not RC-5\n", scancode);
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goto err;
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}
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}
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IR_dprintk(1, "RC-5: bit #%d: %d (%d)\n",
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data->count, bit, data->n_half);
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if (++data->count >= RC5_NBITS) {
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u32 scancode;
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scancode = data->rc5_code.address << 8 |
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data->rc5_code.command;
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IR_dprintk(1, "RC-5 scancode 0x%04x\n", scancode);
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ir_keydown(input_dev, scancode, 0);
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toggle = (scancode & 0x2000) ? 1 : 0;
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data->state = STATE_TRAILER_MARK;
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if (scancode == data->last_code) {
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IR_dprintk(1, "RC-5 repeat\n");
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ir_repeat(input_dev);
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} else {
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data->last_code = scancode;
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scancode &= 0x1fff;
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IR_dprintk(1, "RC-5 scancode 0x%04x\n", scancode);
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ir_keydown(input_dev, scancode, 0);
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}
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data->state = STATE_TRAILER;
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}
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return 0;
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case STATE_TRAILER_MARK:
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if (!last_bit)
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goto err;
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case STATE_TRAILER:
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data->state = STATE_INACTIVE;
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return 0;
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}
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err:
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IR_dprintk(1, "RC-5 decoded failed at state %s (%s) @ %luus\n",
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st_name[data->state],
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bit ? "pulse" : "space",
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IR_dprintk(1, "RC-5 decoded failed at %s @ %luus\n",
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is_pulse ? "pulse" : "space",
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(ev->delta.tv_nsec + 500) / 1000);
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err2:
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data->state = STATE_INACTIVE;
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return -EINVAL;
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}
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