diff options
| author | Russell King <rmk+kernel@armlinux.org.uk> | 2019-02-27 03:04:53 +0300 |
|---|---|---|
| committer | Russell King <rmk+kernel@armlinux.org.uk> | 2019-06-13 23:54:38 +0300 |
| commit | 7dad3740aeb7103817e38a191810dbb81afd692e (patch) | |
| tree | f589d67ea5cb30e0bee910691cad746c97d7b6a9 /drivers/gpu/drm/i2c | |
| parent | 935b9ca357443250fded91fad0e973555528b390 (diff) | |
| download | linux-7dad3740aeb7103817e38a191810dbb81afd692e.tar.xz | |
drm/i2c: tda998x: improve programming of audio divisor
Improve the selection of the audio clock divisor so that more modes
and sample rates work.
Tested-by: Sven Van Asbroeck <TheSven73@gmail.com>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
Diffstat (limited to 'drivers/gpu/drm/i2c')
| -rw-r--r-- | drivers/gpu/drm/i2c/tda998x_drv.c | 44 |
1 files changed, 28 insertions, 16 deletions
diff --git a/drivers/gpu/drm/i2c/tda998x_drv.c b/drivers/gpu/drm/i2c/tda998x_drv.c index 0592fa48e69e..f23aee65846c 100644 --- a/drivers/gpu/drm/i2c/tda998x_drv.c +++ b/drivers/gpu/drm/i2c/tda998x_drv.c @@ -865,6 +865,32 @@ tda998x_write_avi(struct tda998x_priv *priv, const struct drm_display_mode *mode /* Audio support */ +/* + * The audio clock divisor register controls a divider producing Audio_Clk_Out + * from SERclk by dividing it by 2^n where 0 <= n <= 5. We don't know what + * Audio_Clk_Out or SERclk are. We guess SERclk is the same as TMDS clock. + * + * It seems that Audio_Clk_Out must be the smallest value that is greater + * than 128*fs, otherwise audio does not function. There is some suggestion + * that 126*fs is a better value. + */ +static u8 tda998x_get_adiv(struct tda998x_priv *priv, unsigned int fs) +{ + unsigned long min_audio_clk = fs * 128; + unsigned long ser_clk = priv->tmds_clock * 1000; + u8 adiv; + + for (adiv = AUDIO_DIV_SERCLK_32; adiv != AUDIO_DIV_SERCLK_1; adiv--) + if (ser_clk > min_audio_clk << adiv) + break; + + dev_dbg(&priv->hdmi->dev, + "ser_clk=%luHz fs=%uHz min_aclk=%luHz adiv=%d\n", + ser_clk, fs, min_audio_clk, adiv); + + return adiv; +} + static void tda998x_audio_mute(struct tda998x_priv *priv, bool on) { if (on) { @@ -882,6 +908,8 @@ static int tda998x_configure_audio(struct tda998x_priv *priv, u8 buf[6], clksel_aip, clksel_fs, cts_n, adiv; u32 n; + adiv = tda998x_get_adiv(priv, settings->params.sample_rate); + /* Enable audio ports */ reg_write(priv, REG_ENA_AP, settings->params.config); @@ -926,22 +954,6 @@ static int tda998x_configure_audio(struct tda998x_priv *priv, reg_clear(priv, REG_AIP_CNTRL_0, AIP_CNTRL_0_LAYOUT | AIP_CNTRL_0_ACR_MAN); /* auto CTS */ reg_write(priv, REG_CTS_N, cts_n); - - /* - * Audio input somehow depends on HDMI line rate which is - * related to pixclk. Testing showed that modes with pixclk - * >100MHz need a larger divider while <40MHz need the default. - * There is no detailed info in the datasheet, so we just - * assume 100MHz requires larger divider. - */ - adiv = AUDIO_DIV_SERCLK_8; - if (priv->tmds_clock > 100000) - adiv++; /* AUDIO_DIV_SERCLK_16 */ - - /* S/PDIF asks for a larger divider */ - if (settings->params.format == AFMT_SPDIF) - adiv++; /* AUDIO_DIV_SERCLK_16 or _32 */ - reg_write(priv, REG_AUDIO_DIV, adiv); /* |