Re: [PATCH v2 3/6] drm/edid: Add cea_sad helpers for freq/length

On Mon, 20 Sep 2021, Markus Schneider-Pargmann msp@baylibre.com 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@baylibre.com

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);