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

[Jonas Karlman <jonas@kwiboo.se>]

On 2019-09-03 20:08, Jernej Škrabec wrote:
> Hi!
>
> Dne torek, 03. september 2019 ob 20:00:33 CEST je Neil Armstrong napisal(a):
>> Hi,
>>
>> Le 03/09/2019 à 11:53, Neil Armstrong a écrit :
>>> Hi,
>>>
>>> On 03/09/2019 07:51, Cheng-Yi Chiang wrote:
>>>> From: Yakir Yang <ykk@rock-chips.com>
>>>>
>>>> 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@rock-chips.com>
>>>> Signed-off-by: Cheng-Yi Chiang <cychiang@chromium.org>
>>>> ---
>>>>
>>>>  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 ?
>> After investigations, Amlogic sets these registers on their 2.0a version
>> aswell, and Jernej (added in Cc) reported me Allwinner sets them on their
>> < 2.0a and > 2.0a IPs versions.
>>
>> Can you check on the Rockchip IP versions in RK3399 ?
>>
>> For reference, the HDMI 1.4a IP version allwinner setups is:
>> https://github.com/Allwinner-Homlet/H3-BSP4.4-linux/blob/master/drivers/vide
>> o/fbdev/sunxi/disp2/hdmi/hdmi_bsp_sun8iw7.c#L531-L539 (registers a
>> "scrambled" but a custom bit can reset to the original mapping, 0x1066 ...
>> 0x106f)
> For easier reading, here is similar, but annotated version: http://ix.io/1Ub6
> Check function bsp_hdmi_audio().
>
> Unless there is a special reason, you can just remove that check.

Agree, this check should not be needed, AUDSCHNLS7 used to be configured in my old
multi-channel patches that have seen lot of testing on Amlogic, Allwinner and Rockchip SoCs.

>
> Best regards,
> Jernej
>
>> Neil
>>
>>>> +
>>>> +	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;

This looks wrong, user can use 16 and 24 bit wide audio streams.

>>>> +
>>>> +	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);

I will suggest this function is called from or merged with dw_hdmi_set_sample_rate().
Similar to how AUDSCONF and AUDICONF0 is configured from dw_hdmi_set_channel_count().

Regards,
Jonas

>>>>
>>>>  }
>>>>  
>>>>  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,