From: Markus Schneider-Pargmann <msp@baylibre.com>

This patch adds two helper functions that extract the frequency and word
length from a struct cea_sad.

For these helper functions new defines are added that help translate the
'freq' and 'byte2' fields into real numbers.

Signed-off-by: Markus Schneider-Pargmann <msp@baylibre.com>
Signed-off-by: Guillaume Ranquet <granquet@baylibre.com>
---
 drivers/gpu/drm/drm_edid.c | 74 ++++++++++++++++++++++++++++++++++++++
 include/drm/drm_edid.h     | 18 ++++++++--
 2 files changed, 90 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index 12893e7be89bb..500279a82167a 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -4747,6 +4747,80 @@ int drm_edid_to_speaker_allocation(struct edid *edid, u8 **sadb)
 }
 EXPORT_SYMBOL(drm_edid_to_speaker_allocation);
 
+/**
+ * drm_cea_sad_get_sample_rate - Extract the sample rate from cea_sad
+ * @sad: Pointer to the cea_sad struct
+ *
+ * Extracts the cea_sad frequency field and returns the sample rate in Hz.
+ *
+ * Return: Sample rate in Hz or a negative errno if parsing failed.
+ */
+int drm_cea_sad_get_sample_rate(const struct cea_sad *sad)
+{
+	switch (sad->freq) {
+	case DRM_CEA_SAD_FREQ_32KHZ:
+		return 32000;
+	case DRM_CEA_SAD_FREQ_44KHZ:
+		return 44100;
+	case DRM_CEA_SAD_FREQ_48KHZ:
+		return 48000;
+	case DRM_CEA_SAD_FREQ_88KHZ:
+		return 88200;
+	case DRM_CEA_SAD_FREQ_96KHZ:
+		return 96000;
+	case DRM_CEA_SAD_FREQ_176KHZ:
+		return 176400;
+	case DRM_CEA_SAD_FREQ_192KHZ:
+		return 192000;
+	default:
+		return -EINVAL;
+	}
+}
+EXPORT_SYMBOL(drm_cea_sad_get_sample_rate);
+
+static bool drm_cea_sad_is_uncompressed(const struct cea_sad *sad)
+{
+	switch (sad->format) {
+	case HDMI_AUDIO_CODING_TYPE_STREAM:
+	case HDMI_AUDIO_CODING_TYPE_PCM:
+		return true;
+	default:
+		return false;
+	}
+}
+
+/**
+ * drm_cea_sad_get_uncompressed_word_length - Extract word length
+ * @sad: Pointer to the cea_sad struct
+ *
+ * Extracts the cea_sad byte2 field and returns the word length for an
+ * uncompressed stream.
+ *
+ * Note: This function may only be called for uncompressed audio.
+ *
+ * Return: Word length in bits or a negative errno if parsing failed.
+ */
+int drm_cea_sad_get_uncompressed_word_length(const struct cea_sad *sad)
+{
+	if (!drm_cea_sad_is_uncompressed(sad)) {
+		DRM_WARN("Unable to get the uncompressed word length for a compressed format: %u\n",
+			 sad->format);
+		return -EINVAL;
+	}
+
+	switch (sad->byte2) {
+	case DRM_CEA_SAD_UNCOMPRESSED_WORD_16BIT:
+		return 16;
+	case DRM_CEA_SAD_UNCOMPRESSED_WORD_20BIT:
+		return 20;
+	case DRM_CEA_SAD_UNCOMPRESSED_WORD_24BIT:
+		return 24;
+	default:
+		return -EINVAL;
+	}
+}
+EXPORT_SYMBOL(drm_cea_sad_get_uncompressed_word_length);
+
 /**
  * drm_av_sync_delay - compute the HDMI/DP sink audio-video sync delay
  * @connector: connector associated with the HDMI/DP sink
diff --git a/include/drm/drm_edid.h b/include/drm/drm_edid.h
index 18f6c700f6d02..a30452b313979 100644
--- a/include/drm/drm_edid.h
+++ b/include/drm/drm_edid.h
@@ -361,12 +361,24 @@ struct edid {
 
 /* Short Audio Descriptor */
 struct cea_sad {
-	u8 format;
+	u8 format; /* See HDMI_AUDIO_CODING_TYPE_* */
 	u8 channels; /* max number of channels - 1 */
-	u8 freq;
+	u8 freq; /* See CEA_SAD_FREQ_* */
 	u8 byte2; /* meaning depends on format */
 };
 
+#define DRM_CEA_SAD_FREQ_32KHZ  BIT(0)
+#define DRM_CEA_SAD_FREQ_44KHZ  BIT(1)
+#define DRM_CEA_SAD_FREQ_48KHZ  BIT(2)
+#define DRM_CEA_SAD_FREQ_88KHZ  BIT(3)
+#define DRM_CEA_SAD_FREQ_96KHZ  BIT(4)
+#define DRM_CEA_SAD_FREQ_176KHZ BIT(5)
+#define DRM_CEA_SAD_FREQ_192KHZ BIT(6)
+
+#define DRM_CEA_SAD_UNCOMPRESSED_WORD_16BIT BIT(0)
+#define DRM_CEA_SAD_UNCOMPRESSED_WORD_20BIT BIT(1)
+#define DRM_CEA_SAD_UNCOMPRESSED_WORD_24BIT BIT(2)
+
 struct drm_encoder;
 struct drm_connector;
 struct drm_connector_state;
@@ -374,6 +386,8 @@ struct drm_display_mode;
 
 int drm_edid_to_sad(struct edid *edid, struct cea_sad **sads);
 int drm_edid_to_speaker_allocation(struct edid *edid, u8 **sadb);
+int drm_cea_sad_get_sample_rate(const struct cea_sad *sad);
+int drm_cea_sad_get_uncompressed_word_length(const struct cea_sad *sad);
 int drm_av_sync_delay(struct drm_connector *connector,
 		      const struct drm_display_mode *mode);
 
-- 
2.34.1

Il 18/02/22 15:54, Guillaume Ranquet ha scritto:
> From: Markus Schneider-Pargmann <msp@baylibre.com>
> 
> This patch adds two helper functions that extract the frequency and word
> length from a struct cea_sad.
> 
> For these helper functions new defines are added that help translate the
> 'freq' and 'byte2' fields into real numbers.
> 
> Signed-off-by: Markus Schneider-Pargmann <msp@baylibre.com>
> Signed-off-by: Guillaume Ranquet <granquet@baylibre.com>
> ---
>   drivers/gpu/drm/drm_edid.c | 74 ++++++++++++++++++++++++++++++++++++++
>   include/drm/drm_edid.h     | 18 ++++++++--
>   2 files changed, 90 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> index 12893e7be89bb..500279a82167a 100644
> --- a/drivers/gpu/drm/drm_edid.c
> +++ b/drivers/gpu/drm/drm_edid.c
> @@ -4747,6 +4747,80 @@ int drm_edid_to_speaker_allocation(struct edid *edid, u8 **sadb)
>   }
>   EXPORT_SYMBOL(drm_edid_to_speaker_allocation);
>   
> +/**
> + * drm_cea_sad_get_sample_rate - Extract the sample rate from cea_sad
> + * @sad: Pointer to the cea_sad struct
> + *
> + * Extracts the cea_sad frequency field and returns the sample rate in Hz.
> + *
> + * Return: Sample rate in Hz or a negative errno if parsing failed.
> + */
> +int drm_cea_sad_get_sample_rate(const struct cea_sad *sad)
> +{
> +	switch (sad->freq) {
> +	case DRM_CEA_SAD_FREQ_32KHZ:
> +		return 32000;
> +	case DRM_CEA_SAD_FREQ_44KHZ:
> +		return 44100;
> +	case DRM_CEA_SAD_FREQ_48KHZ:
> +		return 48000;
> +	case DRM_CEA_SAD_FREQ_88KHZ:
> +		return 88200;
> +	case DRM_CEA_SAD_FREQ_96KHZ:
> +		return 96000;
> +	case DRM_CEA_SAD_FREQ_176KHZ:
> +		return 176400;
> +	case DRM_CEA_SAD_FREQ_192KHZ:
> +		return 192000;
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +EXPORT_SYMBOL(drm_cea_sad_get_sample_rate);
> +
> +static bool drm_cea_sad_is_uncompressed(const struct cea_sad *sad)
> +{
> +	switch (sad->format) {
> +	case HDMI_AUDIO_CODING_TYPE_STREAM:
> +	case HDMI_AUDIO_CODING_TYPE_PCM:
> +		return true;
> +	default:
> +		return false;
> +	}
> +}
> +
> +/**
> + * drm_cea_sad_get_uncompressed_word_length - Extract word length
> + * @sad: Pointer to the cea_sad struct
> + *
> + * Extracts the cea_sad byte2 field and returns the word length for an
> + * uncompressed stream.
> + *
> + * Note: This function may only be called for uncompressed audio.
> + *
> + * Return: Word length in bits or a negative errno if parsing failed.
> + */
> +int drm_cea_sad_get_uncompressed_word_length(const struct cea_sad *sad)
> +{
> +	if (!drm_cea_sad_is_uncompressed(sad)) {
> +		DRM_WARN("Unable to get the uncompressed word length for a compressed format: %u\n",
> +			 sad->format);
> +		return -EINVAL;
> +	}
> +
> +	switch (sad->byte2) {
> +	case DRM_CEA_SAD_UNCOMPRESSED_WORD_16BIT:
> +		return 16;
> +	case DRM_CEA_SAD_UNCOMPRESSED_WORD_20BIT:
> +		return 20;
> +	case DRM_CEA_SAD_UNCOMPRESSED_WORD_24BIT:
> +		return 24;
> +	default:
> +		return -EINVAL;
> +	}
> +}
> +EXPORT_SYMBOL(drm_cea_sad_get_uncompressed_word_length);
> +
>   /**
>    * drm_av_sync_delay - compute the HDMI/DP sink audio-video sync delay
>    * @connector: connector associated with the HDMI/DP sink
> diff --git a/include/drm/drm_edid.h b/include/drm/drm_edid.h
> index 18f6c700f6d02..a30452b313979 100644
> --- a/include/drm/drm_edid.h
> +++ b/include/drm/drm_edid.h
> @@ -361,12 +361,24 @@ struct edid {
>   
>   /* Short Audio Descriptor */
>   struct cea_sad {
> -	u8 format;
> +	u8 format; /* See HDMI_AUDIO_CODING_TYPE_* */

Hello Guillaume,

since you're adding comments to all the rest of the struct members,
I think that a small effort to instead convert this to kerneldoc is
totally worth it.
Can you please do that?

Thanks,
Angelo

>   	u8 channels; /* max number of channels - 1 */
> -	u8 freq;
> +	u8 freq; /* See CEA_SAD_FREQ_* */
>   	u8 byte2; /* meaning depends on format */
>   };
>   
> +#define DRM_CEA_SAD_FREQ_32KHZ  BIT(0)
> +#define DRM_CEA_SAD_FREQ_44KHZ  BIT(1)
> +#define DRM_CEA_SAD_FREQ_48KHZ  BIT(2)
> +#define DRM_CEA_SAD_FREQ_88KHZ  BIT(3)
> +#define DRM_CEA_SAD_FREQ_96KHZ  BIT(4)
> +#define DRM_CEA_SAD_FREQ_176KHZ BIT(5)
> +#define DRM_CEA_SAD_FREQ_192KHZ BIT(6)
> +
> +#define DRM_CEA_SAD_UNCOMPRESSED_WORD_16BIT BIT(0)
> +#define DRM_CEA_SAD_UNCOMPRESSED_WORD_20BIT BIT(1)
> +#define DRM_CEA_SAD_UNCOMPRESSED_WORD_24BIT BIT(2)
> +
>   struct drm_encoder;
>   struct drm_connector;
>   struct drm_connector_state;
> @@ -374,6 +386,8 @@ struct drm_display_mode;
>   
>   int drm_edid_to_sad(struct edid *edid, struct cea_sad **sads);
>   int drm_edid_to_speaker_allocation(struct edid *edid, u8 **sadb);
> +int drm_cea_sad_get_sample_rate(const struct cea_sad *sad);
> +int drm_cea_sad_get_uncompressed_word_length(const struct cea_sad *sad);
>   int drm_av_sync_delay(struct drm_connector *connector,
>   		      const struct drm_display_mode *mode);
>   

Quoting AngeloGioacchino Del Regno (2022-02-21 15:30:04)
> Il 18/02/22 15:54, Guillaume Ranquet ha scritto:
> > From: Markus Schneider-Pargmann <msp@baylibre.com>
> >
> > This patch adds two helper functions that extract the frequency and word
> > length from a struct cea_sad.
> >
> > For these helper functions new defines are added that help translate the
> > 'freq' and 'byte2' fields into real numbers.
> >
> > Signed-off-by: Markus Schneider-Pargmann <msp@baylibre.com>
> > Signed-off-by: Guillaume Ranquet <granquet@baylibre.com>
> > ---
> >   drivers/gpu/drm/drm_edid.c | 74 ++++++++++++++++++++++++++++++++++++++
> >   include/drm/drm_edid.h     | 18 ++++++++--
> >   2 files changed, 90 insertions(+), 2 deletions(-)
> >
> > diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> > index 12893e7be89bb..500279a82167a 100644
> > --- a/drivers/gpu/drm/drm_edid.c
> > +++ b/drivers/gpu/drm/drm_edid.c
> > @@ -4747,6 +4747,80 @@ int drm_edid_to_speaker_allocation(struct edid *edid, u8 **sadb)
> >   }
> >   EXPORT_SYMBOL(drm_edid_to_speaker_allocation);
> >
> > +/**
> > + * drm_cea_sad_get_sample_rate - Extract the sample rate from cea_sad
> > + * @sad: Pointer to the cea_sad struct
> > + *
> > + * Extracts the cea_sad frequency field and returns the sample rate in Hz.
> > + *
> > + * Return: Sample rate in Hz or a negative errno if parsing failed.
> > + */
> > +int drm_cea_sad_get_sample_rate(const struct cea_sad *sad)
> > +{
> > +     switch (sad->freq) {
> > +     case DRM_CEA_SAD_FREQ_32KHZ:
> > +             return 32000;
> > +     case DRM_CEA_SAD_FREQ_44KHZ:
> > +             return 44100;
> > +     case DRM_CEA_SAD_FREQ_48KHZ:
> > +             return 48000;
> > +     case DRM_CEA_SAD_FREQ_88KHZ:
> > +             return 88200;
> > +     case DRM_CEA_SAD_FREQ_96KHZ:
> > +             return 96000;
> > +     case DRM_CEA_SAD_FREQ_176KHZ:
> > +             return 176400;
> > +     case DRM_CEA_SAD_FREQ_192KHZ:
> > +             return 192000;
> > +     default:
> > +             return -EINVAL;
> > +     }
> > +}
> > +EXPORT_SYMBOL(drm_cea_sad_get_sample_rate);
> > +
> > +static bool drm_cea_sad_is_uncompressed(const struct cea_sad *sad)
> > +{
> > +     switch (sad->format) {
> > +     case HDMI_AUDIO_CODING_TYPE_STREAM:
> > +     case HDMI_AUDIO_CODING_TYPE_PCM:
> > +             return true;
> > +     default:
> > +             return false;
> > +     }
> > +}
> > +
> > +/**
> > + * drm_cea_sad_get_uncompressed_word_length - Extract word length
> > + * @sad: Pointer to the cea_sad struct
> > + *
> > + * Extracts the cea_sad byte2 field and returns the word length for an
> > + * uncompressed stream.
> > + *
> > + * Note: This function may only be called for uncompressed audio.
> > + *
> > + * Return: Word length in bits or a negative errno if parsing failed.
> > + */
> > +int drm_cea_sad_get_uncompressed_word_length(const struct cea_sad *sad)
> > +{
> > +     if (!drm_cea_sad_is_uncompressed(sad)) {
> > +             DRM_WARN("Unable to get the uncompressed word length for a compressed format: %u\n",
> > +                      sad->format);
> > +             return -EINVAL;
> > +     }
> > +
> > +     switch (sad->byte2) {
> > +     case DRM_CEA_SAD_UNCOMPRESSED_WORD_16BIT:
> > +             return 16;
> > +     case DRM_CEA_SAD_UNCOMPRESSED_WORD_20BIT:
> > +             return 20;
> > +     case DRM_CEA_SAD_UNCOMPRESSED_WORD_24BIT:
> > +             return 24;
> > +     default:
> > +             return -EINVAL;
> > +     }
> > +}
> > +EXPORT_SYMBOL(drm_cea_sad_get_uncompressed_word_length);
> > +
> >   /**
> >    * drm_av_sync_delay - compute the HDMI/DP sink audio-video sync delay
> >    * @connector: connector associated with the HDMI/DP sink
> > diff --git a/include/drm/drm_edid.h b/include/drm/drm_edid.h
> > index 18f6c700f6d02..a30452b313979 100644
> > --- a/include/drm/drm_edid.h
> > +++ b/include/drm/drm_edid.h
> > @@ -361,12 +361,24 @@ struct edid {
> >
> >   /* Short Audio Descriptor */
> >   struct cea_sad {
> > -     u8 format;
> > +     u8 format; /* See HDMI_AUDIO_CODING_TYPE_* */
>
> Hello Guillaume,
>
> since you're adding comments to all the rest of the struct members,
> I think that a small effort to instead convert this to kerneldoc is
> totally worth it.
> Can you please do that?
>
> Thanks,
> Angelo
>
Hello Angelo,

Sure, that's a good suggestion.

Thx,
Guillaume.
> >       u8 channels; /* max number of channels - 1 */
> > -     u8 freq;
> > +     u8 freq; /* See CEA_SAD_FREQ_* */
> >       u8 byte2; /* meaning depends on format */
> >   };
> >
> > +#define DRM_CEA_SAD_FREQ_32KHZ  BIT(0)
> > +#define DRM_CEA_SAD_FREQ_44KHZ  BIT(1)
> > +#define DRM_CEA_SAD_FREQ_48KHZ  BIT(2)
> > +#define DRM_CEA_SAD_FREQ_88KHZ  BIT(3)
> > +#define DRM_CEA_SAD_FREQ_96KHZ  BIT(4)
> > +#define DRM_CEA_SAD_FREQ_176KHZ BIT(5)
> > +#define DRM_CEA_SAD_FREQ_192KHZ BIT(6)
> > +
> > +#define DRM_CEA_SAD_UNCOMPRESSED_WORD_16BIT BIT(0)
> > +#define DRM_CEA_SAD_UNCOMPRESSED_WORD_20BIT BIT(1)
> > +#define DRM_CEA_SAD_UNCOMPRESSED_WORD_24BIT BIT(2)
> > +
> >   struct drm_encoder;
> >   struct drm_connector;
> >   struct drm_connector_state;
> > @@ -374,6 +386,8 @@ struct drm_display_mode;
> >
> >   int drm_edid_to_sad(struct edid *edid, struct cea_sad **sads);
> >   int drm_edid_to_speaker_allocation(struct edid *edid, u8 **sadb);
> > +int drm_cea_sad_get_sample_rate(const struct cea_sad *sad);
> > +int drm_cea_sad_get_uncompressed_word_length(const struct cea_sad *sad);
> >   int drm_av_sync_delay(struct drm_connector *connector,
> >                     const struct drm_display_mode *mode);
> >
>
>