Re: [PATCH v2] drm: bridge/dw_hdmi: add audio sample channel status setting

From: Russell King - ARM Linux admin
Date: Sun Sep 08 2019 - 14:38:56 EST

On Thu, Sep 05, 2019 at 05:43:25PM +0800, Cheng-Yi Chiang wrote:
> From: Yakir Yang <ykk@xxxxxxxxxxxxxx>
>
> When transmitting IEC60985 linear PCM audio, we configure the
> Aduio 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)
>
> Note that these registers are only for interfaces:
> I2S audio interface, General Purpose Audio (GPA), or AHB audio DMA
> (AHBAUDDMA).
> For S/PDIF interface this information comes from the stream.
>
> Currently this function dw_hdmi_set_channel_status is only called
> from dw-hdmi-i2s-audio in I2S setup.
>
> Signed-off-by: Yakir Yang <ykk@xxxxxxxxxxxxxx>
> Signed-off-by: Cheng-Yi Chiang <cychiang@xxxxxxxxxxxx>
> ---
> Original patch by Yakir Yang is at
>
> https://lore.kernel.org/patchwork/patch/539653/
>
> Change from v1 to v2:
> 1. Remove the version check because this will only be called by
> dw-hdmi-i2s-audio, and the registers are available in I2S setup.
> 2. Set these registers in dw_hdmi_i2s_hw_params.
> 3. Fix the sample width setting so it can use 16 or 24 bits.
>
> .../drm/bridge/synopsys/dw-hdmi-i2s-audio.c | 1 +
> drivers/gpu/drm/bridge/synopsys/dw-hdmi.c | 70 +++++++++++++++++++
> drivers/gpu/drm/bridge/synopsys/dw-hdmi.h | 20 ++++++
> include/drm/bridge/dw_hdmi.h | 2 +
> 4 files changed, 93 insertions(+)
>
> diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi-i2s-audio.c b/drivers/gpu/drm/bridge/synopsys/dw-hdmi-i2s-audio.c
> index 34d8e837555f..b801a28b0f17 100644
> --- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi-i2s-audio.c
> +++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi-i2s-audio.c
> @@ -102,6 +102,7 @@ static int dw_hdmi_i2s_hw_params(struct device *dev, void *data,
> }
>
> dw_hdmi_set_sample_rate(hdmi, hparms->sample_rate);
> + dw_hdmi_set_channel_status(hdmi, hparms->sample_width);
> dw_hdmi_set_channel_count(hdmi, hparms->channels);
> dw_hdmi_set_channel_allocation(hdmi, hparms->cea.channel_allocation);
>

dw_hdmi_i2s_hw_params() is passed the channel status data in
hparams->iec.status Rather than re-creating it afresh in the driver,
I'd recommend programming the already supplied channel status data
into the registers.

> diff --git a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> index bd65d0479683..d1daa369c8ae 100644
> --- a/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> +++ b/drivers/gpu/drm/bridge/synopsys/dw-hdmi.c
> @@ -582,6 +582,76 @@ static unsigned int hdmi_compute_n(unsigned int freq, unsigned long pixel_clk)
> return n;
> }
>
> +/*
> + * When transmitting IEC60958 linear PCM audio, these registers allow to
> + * configure the channel status information of all the channel status
> + * bits in the IEC60958 frame. For the moment this configuration is only
> + * used when the I2S audio interface, General Purpose Audio (GPA),
> + * or AHB audio DMA (AHBAUDDMA) interface is active
> + * (for S/PDIF interface this information comes from the stream).
> + */
> +void dw_hdmi_set_channel_status(struct dw_hdmi *hdmi,
> + unsigned int sample_width)
> +{
> + u8 aud_schnl_samplerate;
> + u8 aud_schnl_8;
> + u8 word_length_bits;
> +
> + 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;
> +
> + /*
> + * Refer to IEC60958-3 page 12. We can accept 16 bits or 24 bits.
> + * Otherwise, set the register to 0t o indicate using default value.
> + */
> + word_length_bits = (sample_width == 16) ? 0x2 :
> + ((sample_width == 24) ? 0xb : 0);
> +
> + aud_schnl_8 |= word_length_bits << HDMI_FC_AUDSCHNLS8_WORDLEGNTH_OFFSET;
> +
> + hdmi_writeb(hdmi, aud_schnl_8, HDMI_FC_AUDSCHNLS8);
> +}
> +EXPORT_SYMBOL_GPL(dw_hdmi_set_channel_status);

As mentioned above, the channel status data is actually already
provided - so we don't really need the above at all. It just
needs the data programmed into the registers.

> +
> static void hdmi_set_clk_regenerator(struct dw_hdmi *hdmi,
> unsigned long pixel_clk, unsigned int sample_rate)
> {
> 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,

These look very much like the IEC958_AES* consumer definitions in
include/sound/asoundef.h.

> /* HDMI_FC_AUDSCHNLS8 field values */
> HDMI_FC_AUDSCHNLS8_ORIGSAMPFREQ_MASK = 0xf0,
> diff --git a/include/drm/bridge/dw_hdmi.h b/include/drm/bridge/dw_hdmi.h
> index cf528c289857..12144d2f80f4 100644
> --- a/include/drm/bridge/dw_hdmi.h
> +++ b/include/drm/bridge/dw_hdmi.h
> @@ -156,6 +156,8 @@ void dw_hdmi_setup_rx_sense(struct dw_hdmi *hdmi, bool hpd, bool rx_sense);
>
> void dw_hdmi_set_sample_rate(struct dw_hdmi *hdmi, unsigned int rate);
> void dw_hdmi_set_channel_count(struct dw_hdmi *hdmi, unsigned int cnt);
> +void dw_hdmi_set_channel_status(struct dw_hdmi *hdmi,
> + unsigned int sample_width);
> void dw_hdmi_set_channel_allocation(struct dw_hdmi *hdmi, unsigned int ca);
> void dw_hdmi_audio_enable(struct dw_hdmi *hdmi);
> void dw_hdmi_audio_disable(struct dw_hdmi *hdmi);
> --
> 2.23.0.187.g17f5b7556c-goog
>
>
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