On Mon, 20 Sep 2021, Markus Schneider-Pargmann <msp@xxxxxxxxxxxx> wrote:
> 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@xxxxxxxxxxxx>
> ---
>
> Notes:
> Changes v1 -> v2:
> - Use const struct pointers.
> - Add a check whether the format is actually uncompressed or not.
>
> 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 6325877c5fd6..28df422fbc03 100644
> --- a/drivers/gpu/drm/drm_edid.c
> +++ b/drivers/gpu/drm/drm_edid.c
> @@ -4666,6 +4666,80 @@ 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 CEA_SAD_FREQ_32KHZ:
> + return 32000;
> + case CEA_SAD_FREQ_44KHZ:
> + return 44100;
> + case CEA_SAD_FREQ_48KHZ:
> + return 48000;
> + case CEA_SAD_FREQ_88KHZ:
> + return 88200;
> + case CEA_SAD_FREQ_96KHZ:
> + return 96000;
> + case CEA_SAD_FREQ_176KHZ:
> + return 176400;
> + case 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 CEA_SAD_UNCOMPRESSED_WORD_16BIT:
> + return 16;
> + case CEA_SAD_UNCOMPRESSED_WORD_20BIT:
> + return 20;
> + case 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 deccfd39e6db..7b7d71a7154d 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 CEA_SAD_FREQ_32KHZ BIT(0)
> +#define CEA_SAD_FREQ_44KHZ BIT(1)
> +#define CEA_SAD_FREQ_48KHZ BIT(2)
> +#define CEA_SAD_FREQ_88KHZ BIT(3)
> +#define CEA_SAD_FREQ_96KHZ BIT(4)
> +#define CEA_SAD_FREQ_176KHZ BIT(5)
> +#define CEA_SAD_FREQ_192KHZ BIT(6)
> +
> +#define CEA_SAD_UNCOMPRESSED_WORD_16BIT BIT(0)
> +#define CEA_SAD_UNCOMPRESSED_WORD_20BIT BIT(1)
> +#define CEA_SAD_UNCOMPRESSED_WORD_24BIT BIT(2)
I suggest adding DRM_ prefixes here.
BR,
Jani.
> +
> 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);
--
Jani Nikula, Intel Open Source Graphics Center
