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Commit 02004681 authored by Antti Palosaari's avatar Antti Palosaari Committed by Mauro Carvalho Chehab
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[media] msi3101: enhance sampling results 

It looks like there is some extra data carried to enhance sampling
results. When you tune to some some weak/empty channel those bits
are always zeroes. When you tune to some channel where is very
strong signals those bits are all zeroes.
Examining those 32-bits reveals shortly there is 16 pieces of 2-bit
numbers. Number seen are 0, 1 and 3 - for some reason 2 is not used.
I used that number to shift bits given amount to left, "increasing"
sampling resolution by 3-bits. It may be wrong, but after some testing
it still provides better signal.
Signed-off-by: default avatarAntti Palosaari <crope@iki.fi>
Signed-off-by: default avatarMauro Carvalho Chehab <m.chehab@samsung.com>
parent 3673b35c
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Inline Side-by-side
Showing with 67 additions and 53 deletions
drivers/staging/media/msi3101/sdr-msi3101.c
View file @ 02004681
......@@ -409,6 +409,7 @@ struct msi3101_state {
u32 next_sample; /* for track lost packets */
u32 sample; /* for sample rate calc */
unsigned long jiffies;
unsigned int sample_ctrl_bit[4];
};
/* Private functions */
......@@ -429,6 +430,51 @@ static struct msi3101_frame_buf *msi3101_get_next_fill_buf(
return buf;
}
/*
* +===========================================================================
* | 00-1024 | USB packet
* +===========================================================================
* | 00- 03 | sequence number of first sample in that USB packet
* +---------------------------------------------------------------------------
* | 04- 15 | garbage
* +---------------------------------------------------------------------------
* | 16- 175 | samples
* +---------------------------------------------------------------------------
* | 176- 179 | control bits for previous samples
* +---------------------------------------------------------------------------
* | 180- 339 | samples
* +---------------------------------------------------------------------------
* | 340- 343 | control bits for previous samples
* +---------------------------------------------------------------------------
* | 344- 503 | samples
* +---------------------------------------------------------------------------
* | 504- 507 | control bits for previous samples
* +---------------------------------------------------------------------------
* | 508- 667 | samples
* +---------------------------------------------------------------------------
* | 668- 671 | control bits for previous samples
* +---------------------------------------------------------------------------
* | 672- 831 | samples
* +---------------------------------------------------------------------------
* | 832- 835 | control bits for previous samples
* +---------------------------------------------------------------------------
* | 836- 995 | samples
* +---------------------------------------------------------------------------
* | 996- 999 | control bits for previous samples
* +---------------------------------------------------------------------------
* | 1000-1024 | garbage
* +---------------------------------------------------------------------------
*
* Bytes 4 - 7 could have some meaning?
*
* Control bits for previous samples is 32-bit field, containing 16 x 2-bit
* numbers. This results one 2-bit number for 8 samples. It is likely used for
* for bit shifting sample by given bits, increasing actual sampling resolution.
* Number 2 (0b10) was never seen.
*
* 6 * 16 * 2 * 4 = 768 samples. 768 * 4 = 3072 bytes
*/
/*
* Converts signed 10-bit integer into 32-bit IEEE floating point
* representation.
......@@ -438,20 +484,24 @@ static struct msi3101_frame_buf *msi3101_get_next_fill_buf(
*/
#define I2F_FRAC_BITS 23
#define I2F_MASK ((1 << I2F_FRAC_BITS) - 1)
static uint32_t msi3101_int2float(uint32_t x)
static u32 msi3101_convert_sample(struct msi3101_state *s, u16 x, int shift)
{
uint32_t msb, exponent, fraction, sign;
u32 msb, exponent, fraction, sign;
s->sample_ctrl_bit[shift]++;
/* Zero is special */
if (!x)
return 0;
/* Negative / positive value */
if (x & 0x200) {
/* Convert 10-bit two's complement to 13-bit */
if (x & (1 << 9)) {
x |= ~0U << 10; /* set all the rest bits to one */
x <<= shift;
x = -x;
x &= 0x3ff;
x &= 0xfff; /* result is 12 bit ... + sign */
sign = 1 << 31;
} else {
x <<= shift;
sign = 0 << 31;
}
......@@ -476,6 +526,7 @@ static int msi3101_convert_stream(struct msi3101_state *s, u32 *dst,
{
int i, j, k, l, i_max, dst_len = 0;
u16 sample[4];
u32 bits;
#ifdef MSI3101_EXTENSIVE_DEBUG
u32 sample_num[3];
#endif
......@@ -493,6 +544,7 @@ static int msi3101_convert_stream(struct msi3101_state *s, u32 *dst,
#endif
src += 16;
for (j = 0; j < 6; j++) {
bits = src[160 + 3] << 24 | src[160 + 2] << 16 | src[160 + 1] << 8 | src[160 + 0] << 0;
for (k = 0; k < 16; k++) {
for (l = 0; l < 10; l += 5) {
sample[0] = (src[l + 0] & 0xff) >> 0 | (src[l + 1] & 0x03) << 8;
......@@ -500,10 +552,10 @@ static int msi3101_convert_stream(struct msi3101_state *s, u32 *dst,
sample[2] = (src[l + 2] & 0xf0) >> 4 | (src[l + 3] & 0x3f) << 4;
sample[3] = (src[l + 3] & 0xc0) >> 6 | (src[l + 4] & 0xff) << 2;
*dst++ = msi3101_int2float(sample[0]);
*dst++ = msi3101_int2float(sample[1]);
*dst++ = msi3101_int2float(sample[2]);
*dst++ = msi3101_int2float(sample[3]);
*dst++ = msi3101_convert_sample(s, sample[0], (bits >> (2 * k)) & 0x3);
*dst++ = msi3101_convert_sample(s, sample[1], (bits >> (2 * k)) & 0x3);
*dst++ = msi3101_convert_sample(s, sample[2], (bits >> (2 * k)) & 0x3);
*dst++ = msi3101_convert_sample(s, sample[3], (bits >> (2 * k)) & 0x3);
/* 4 x 32bit float samples */
dst_len += 4 * 4;
......@@ -511,9 +563,8 @@ static int msi3101_convert_stream(struct msi3101_state *s, u32 *dst,
src += 10;
}
#ifdef MSI3101_EXTENSIVE_DEBUG
if (memcmp(src, "\xff\xff\xff\xff", 4) && memcmp(src, "\x00\x00\x00\x00", 4))
dev_dbg_ratelimited(&s->udev->dev,
"padding %*ph\n", 4, src);
dev_dbg_ratelimited(&s->udev->dev,
"sample control bits %08x\n", bits);
#endif
src += 4;
}
......@@ -529,9 +580,11 @@ static int msi3101_convert_stream(struct msi3101_state *s, u32 *dst,
s->jiffies = jiffies_now;
s->sample = sample_num[i_max - 1];
dev_dbg(&s->udev->dev,
"slen=%d samples=%u msecs=%lu sampling rate=%lu\n",
"slen=%d samples=%u msecs=%lu sampling rate=%lu bits=%d.%d.%d.%d\n",
src_len, samples, msecs,
samples * 1000UL / msecs);
samples * 1000UL / msecs,
s->sample_ctrl_bit[0], s->sample_ctrl_bit[1],
s->sample_ctrl_bit[2], s->sample_ctrl_bit[3]);
}
/* next sample (sample = sample + i * 384) */
......@@ -833,45 +886,6 @@ static int msi3101_buf_prepare(struct vb2_buffer *vb)
return 0;
}
/*
* +===========================================================================
* | 00-1024 | USB packet
* +===========================================================================
* | 00- 03 | packet address
* +---------------------------------------------------------------------------
* | 04- 15 | garbage
* +---------------------------------------------------------------------------
* | 16- 175 | samples
* +---------------------------------------------------------------------------
* | 176- 179 | padding
* +---------------------------------------------------------------------------
* | 180- 339 | samples
* +---------------------------------------------------------------------------
* | 340- 343 | padding
* +---------------------------------------------------------------------------
* | 344- 503 | samples
* +---------------------------------------------------------------------------
* | 504- 507 | padding
* +---------------------------------------------------------------------------
* | 508- 667 | samples
* +---------------------------------------------------------------------------
* | 668- 671 | padding
* +---------------------------------------------------------------------------
* | 672- 831 | samples
* +---------------------------------------------------------------------------
* | 832- 835 | padding
* +---------------------------------------------------------------------------
* | 836- 995 | samples
* +---------------------------------------------------------------------------
* | 996- 999 | padding
* +---------------------------------------------------------------------------
* | 1000-1024 | garbage
* +---------------------------------------------------------------------------
*
* bytes 4 - 7 could have some meaning?
* padding is "00 00 00 00" or "ff ff ff ff"
* 6 * 16 * 2 * 4 = 768 samples. 768 * 4 = 3072 bytes
*/
#ifdef MSI3101_CONVERT_IN_URB_HANDLER
static int msi3101_buf_finish(struct vb2_buffer *vb)
{
......
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