Re: [PATCH] drm: bridge/dw_hdmi: add audio sample channel status setting

[Neil Armstrong]

Hi,

On 03/09/2019 07:51, Cheng-Yi Chiang wrote:
> From: Yakir Yang <ykk@xxxxxxxxxxxxxx>
> 
> When transmitting IEC60985 linear PCM audio, we configure the
> Audio Sample Channel Status information of all the channel
> status bits in the IEC60958 frame.
> Refer to 60958-3 page 10 for frequency, original frequency, and
> wordlength setting.
> 
> This fix the issue that audio does not come out on some monitors
> (e.g. LG 22CV241)
> 
> Signed-off-by: Yakir Yang <ykk@xxxxxxxxxxxxxx>
> Signed-off-by: Cheng-Yi Chiang <cychiang@xxxxxxxxxxxx>
> ---
>  drivers/gpu/drm/bridge/synopsys/dw-hdmi.c | 59 +++++++++++++++++++++++
>  drivers/gpu/drm/bridge/synopsys/dw-hdmi.h | 20 ++++++++
>  2 files changed, 79 insertions(+)
> 
> diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> index bd65d0479683..34d46e25d610 100644
> --- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> +++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> @@ -582,6 +582,63 @@ static unsigned int hdmi_compute_n(unsigned int freq, unsigned long pixel_clk)
>  	return n;
>  }
>  
> +static void hdmi_set_schnl(struct dw_hdmi *hdmi)
> +{
> +	u8 aud_schnl_samplerate;
> +	u8 aud_schnl_8;
> +
> +	/* These registers are on RK3288 using version 2.0a. */
> +	if (hdmi->version != 0x200a)
> +		return;

Are these limited to the 2.0a version *in* RK3288, or 2.0a version on all
SoCs ?

> +
> +	switch (hdmi->sample_rate) {
> +	case 32000:
> +		aud_schnl_samplerate = HDMI_FC_AUDSCHNLS7_SMPRATE_32K;
> +		break;
> +	case 44100:
> +		aud_schnl_samplerate = HDMI_FC_AUDSCHNLS7_SMPRATE_44K1;
> +		break;
> +	case 48000:
> +		aud_schnl_samplerate = HDMI_FC_AUDSCHNLS7_SMPRATE_48K;
> +		break;
> +	case 88200:
> +		aud_schnl_samplerate = HDMI_FC_AUDSCHNLS7_SMPRATE_88K2;
> +		break;
> +	case 96000:
> +		aud_schnl_samplerate = HDMI_FC_AUDSCHNLS7_SMPRATE_96K;
> +		break;
> +	case 176400:
> +		aud_schnl_samplerate = HDMI_FC_AUDSCHNLS7_SMPRATE_176K4;
> +		break;
> +	case 192000:
> +		aud_schnl_samplerate = HDMI_FC_AUDSCHNLS7_SMPRATE_192K;
> +		break;
> +	case 768000:
> +		aud_schnl_samplerate = HDMI_FC_AUDSCHNLS7_SMPRATE_768K;
> +		break;
> +	default:
> +		dev_warn(hdmi->dev, "Unsupported audio sample rate (%u)\n",
> +			 hdmi->sample_rate);
> +		return;
> +	}
> +
> +	/* set channel status register */
> +	hdmi_modb(hdmi, aud_schnl_samplerate, HDMI_FC_AUDSCHNLS7_SMPRATE_MASK,
> +		  HDMI_FC_AUDSCHNLS7);
> +
> +	/*
> +	 * Set original frequency to be the same as frequency.
> +	 * Use one-complement value as stated in IEC60958-3 page 13.
> +	 */
> +	aud_schnl_8 = (~aud_schnl_samplerate) <<
> +			HDMI_FC_AUDSCHNLS8_ORIGSAMPFREQ_OFFSET;
> +
> +	/* This means word length is 16 bit. Refer to IEC60958-3 page 12. */
> +	aud_schnl_8 |= 2 << HDMI_FC_AUDSCHNLS8_WORDLEGNTH_OFFSET;
> +
> +	hdmi_writeb(hdmi, aud_schnl_8, HDMI_FC_AUDSCHNLS8);
> +}
> +
>  static void hdmi_set_clk_regenerator(struct dw_hdmi *hdmi,
>  	unsigned long pixel_clk, unsigned int sample_rate)
>  {
> @@ -620,6 +677,8 @@ static void hdmi_set_clk_regenerator(struct dw_hdmi *hdmi,
>  	hdmi->audio_cts = cts;
>  	hdmi_set_cts_n(hdmi, cts, hdmi->audio_enable ? n : 0);
>  	spin_unlock_irq(&hdmi->audio_lock);
> +
> +	hdmi_set_schnl(hdmi);
>  }
>  
>  static void hdmi_init_clk_regenerator(struct dw_hdmi *hdmi)
> diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.h b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.h
> index 6988f12d89d9..619ebc1c8354 100644
> --- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.h
> +++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.h
> @@ -158,6 +158,17 @@
>  #define HDMI_FC_SPDDEVICEINF                    0x1062
>  #define HDMI_FC_AUDSCONF                        0x1063
>  #define HDMI_FC_AUDSSTAT                        0x1064
> +#define HDMI_FC_AUDSV                           0x1065
> +#define HDMI_FC_AUDSU                           0x1066
> +#define HDMI_FC_AUDSCHNLS0                      0x1067
> +#define HDMI_FC_AUDSCHNLS1                      0x1068
> +#define HDMI_FC_AUDSCHNLS2                      0x1069
> +#define HDMI_FC_AUDSCHNLS3                      0x106a
> +#define HDMI_FC_AUDSCHNLS4                      0x106b
> +#define HDMI_FC_AUDSCHNLS5                      0x106c
> +#define HDMI_FC_AUDSCHNLS6                      0x106d
> +#define HDMI_FC_AUDSCHNLS7                      0x106e
> +#define HDMI_FC_AUDSCHNLS8                      0x106f
>  #define HDMI_FC_DATACH0FILL                     0x1070
>  #define HDMI_FC_DATACH1FILL                     0x1071
>  #define HDMI_FC_DATACH2FILL                     0x1072
> @@ -706,6 +717,15 @@ enum {
>  /* HDMI_FC_AUDSCHNLS7 field values */
>  	HDMI_FC_AUDSCHNLS7_ACCURACY_OFFSET = 4,
>  	HDMI_FC_AUDSCHNLS7_ACCURACY_MASK = 0x30,
> +	HDMI_FC_AUDSCHNLS7_SMPRATE_MASK = 0x0f,
> +	HDMI_FC_AUDSCHNLS7_SMPRATE_192K = 0xe,
> +	HDMI_FC_AUDSCHNLS7_SMPRATE_176K4 = 0xc,
> +	HDMI_FC_AUDSCHNLS7_SMPRATE_96K = 0xa,
> +	HDMI_FC_AUDSCHNLS7_SMPRATE_768K = 0x9,
> +	HDMI_FC_AUDSCHNLS7_SMPRATE_88K2 = 0x8,
> +	HDMI_FC_AUDSCHNLS7_SMPRATE_32K = 0x3,
> +	HDMI_FC_AUDSCHNLS7_SMPRATE_48K = 0x2,
> +	HDMI_FC_AUDSCHNLS7_SMPRATE_44K1 = 0x0,
>  
>  /* HDMI_FC_AUDSCHNLS8 field values */
>  	HDMI_FC_AUDSCHNLS8_ORIGSAMPFREQ_MASK = 0xf0,
>