From d3749e64c4be27a3230d2a602c928d10eb2dd815 Mon Sep 17 00:00:00 2001 From: Andy Walls Date: Wed, 23 Jul 2008 19:28:23 -0400 Subject: cx18: Fix 32 kHz audio sample output rate for analog tuner SIF input From: Andy Walls cx18: Fix 32 kHz audio sample output rate for analog tuner SIF input so it works. The AUX_PLL VCO was being operated at 196.6 MHz out of the spec'ed 200-600 MHz range. Fixed the multipler and post dividers to operate the VCO within specification and added comments on how magic numbers are derived. Thanks to Hans Verkuil for pointing out this interesting problem to solve. Signed-off-by: Andy Walls --- linux/drivers/media/video/cx18/cx18-av-audio.c | 41 ++++++++++++++++++-------- 1 file changed, 29 insertions(+), 12 deletions(-) (limited to 'linux/drivers') diff --git a/linux/drivers/media/video/cx18/cx18-av-audio.c b/linux/drivers/media/video/cx18/cx18-av-audio.c index c40a286de..7245d37ef 100644 --- a/linux/drivers/media/video/cx18/cx18-av-audio.c +++ b/linux/drivers/media/video/cx18/cx18-av-audio.c @@ -30,7 +30,6 @@ static int set_audclk_freq(struct cx18 *cx, u32 freq) if (freq != 32000 && freq != 44100 && freq != 48000) return -EINVAL; - /* common for all inputs and rates */ /* SA_MCLK_SEL=1, SA_MCLK_DIV=0x10 */ cx18_av_write(cx, 0x127, 0x50); @@ -38,15 +37,20 @@ static int set_audclk_freq(struct cx18 *cx, u32 freq) switch (freq) { case 32000: /* VID_PLL and AUX_PLL */ - cx18_av_write4(cx, 0x108, 0x1006040f); + cx18_av_write4(cx, 0x108, 0x1408040f); /* AUX_PLL_FRAC */ - cx18_av_write4(cx, 0x110, 0x01bb39ee); + /* 0x8.9504318a * 28,636,363.636 / 0x14 = 32000 * 384 */ + cx18_av_write4(cx, 0x110, 0x012a0863); - /* src3/4/6_ctl = 0x0801f77f */ + /* src3/4/6_ctl */ + /* 0x1.f77f = (4 * 15734.26) / 32000 */ cx18_av_write4(cx, 0x900, 0x0801f77f); cx18_av_write4(cx, 0x904, 0x0801f77f); cx18_av_write4(cx, 0x90c, 0x0801f77f); + + /* SA_MCLK_SEL=1, SA_MCLK_DIV=0x14 */ + cx18_av_write(cx, 0x127, 0x54); break; case 44100: @@ -54,9 +58,11 @@ static int set_audclk_freq(struct cx18 *cx, u32 freq) cx18_av_write4(cx, 0x108, 0x1009040f); /* AUX_PLL_FRAC */ + /* 0x9.7635eb * 28,636,363 / 0x10 = 44100 * 384 */ cx18_av_write4(cx, 0x110, 0x00ec6bd6); - /* src3/4/6_ctl = 0x08016d59 */ + /* src3/4/6_ctl */ + /* 0x1.6d59 = (4 * 15734.26) / 44100 */ cx18_av_write4(cx, 0x900, 0x08016d59); cx18_av_write4(cx, 0x904, 0x08016d59); cx18_av_write4(cx, 0x90c, 0x08016d59); @@ -67,9 +73,11 @@ static int set_audclk_freq(struct cx18 *cx, u32 freq) cx18_av_write4(cx, 0x108, 0x100a040f); /* AUX_PLL_FRAC */ + /* 0xa.4c6b728 * 28,636,363 / 0x10 = 48000 * 384 */ cx18_av_write4(cx, 0x110, 0x0098d6e5); - /* src3/4/6_ctl = 0x08014faa */ + /* src3/4/6_ctl */ + /* 0x1.4faa = (4 * 15734.26) / 48000 */ cx18_av_write4(cx, 0x900, 0x08014faa); cx18_av_write4(cx, 0x904, 0x08014faa); cx18_av_write4(cx, 0x90c, 0x08014faa); @@ -82,12 +90,15 @@ static int set_audclk_freq(struct cx18 *cx, u32 freq) cx18_av_write4(cx, 0x108, 0x1e08040f); /* AUX_PLL_FRAC */ + /* 0x8.9504348 * 28,636,363 / 0x1e = 32000 * 256 */ cx18_av_write4(cx, 0x110, 0x012a0869); - /* src1_ctl = 0x08010000 */ + /* src1_ctl */ + /* 0x1.0000 = 32000/32000 */ cx18_av_write4(cx, 0x8f8, 0x08010000); - /* src3/4/6_ctl = 0x08020000 */ + /* src3/4/6_ctl */ + /* 0x2.0000 = 2 * (32000/32000) */ cx18_av_write4(cx, 0x900, 0x08020000); cx18_av_write4(cx, 0x904, 0x08020000); cx18_av_write4(cx, 0x90c, 0x08020000); @@ -101,12 +112,15 @@ static int set_audclk_freq(struct cx18 *cx, u32 freq) cx18_av_write4(cx, 0x108, 0x1809040f); /* AUX_PLL_FRAC */ + /* 0x9.76346B * 28,636,363 / 0x18 = 44100 * 256 */ cx18_av_write4(cx, 0x110, 0x00ec6bd6); - /* src1_ctl = 0x08010000 */ + /* src1_ctl */ + /* 0x1.60cd = 44100/32000 */ cx18_av_write4(cx, 0x8f8, 0x080160cd); - /* src3/4/6_ctl = 0x08020000 */ + /* src3/4/6_ctl */ + /* 0x1.7385 = 2 * (32000/44100) */ cx18_av_write4(cx, 0x900, 0x08017385); cx18_av_write4(cx, 0x904, 0x08017385); cx18_av_write4(cx, 0x90c, 0x08017385); @@ -117,12 +131,15 @@ static int set_audclk_freq(struct cx18 *cx, u32 freq) cx18_av_write4(cx, 0x108, 0x180a040f); /* AUX_PLL_FRAC */ + /* 0xa.4c6b728 * 28,636,363 / 0x18 = 48000 * 256 */ cx18_av_write4(cx, 0x110, 0x0098d6e5); - /* src1_ctl = 0x08010000 */ + /* src1_ctl */ + /* 0x1.8000 = 48000/32000 */ cx18_av_write4(cx, 0x8f8, 0x08018000); - /* src3/4/6_ctl = 0x08020000 */ + /* src3/4/6_ctl */ + /* 0x1.5555 = 2 * (32000/48000) */ cx18_av_write4(cx, 0x900, 0x08015555); cx18_av_write4(cx, 0x904, 0x08015555); cx18_av_write4(cx, 0x90c, 0x08015555); -- cgit v1.2.3