To help to determine if digital display port needs to enable audio output or not. This one adds a helper to get monitor's audio capability via EDID CEA extension block.
Tested-by: Wu Fengguang fengguang.wu@intel.com Signed-off-by: Zhenyu Wang zhenyuw@linux.intel.com --- drivers/gpu/drm/drm_edid.c | 92 +++++++++++++++++++++++++++++++++++++------- include/drm/drm_crtc.h | 1 + 2 files changed, 79 insertions(+), 14 deletions(-)
diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c index 96e9631..7f356af 100644 --- a/drivers/gpu/drm/drm_edid.c +++ b/drivers/gpu/drm/drm_edid.c @@ -1268,34 +1268,51 @@ add_detailed_modes(struct drm_connector *connector, struct edid *edid, }
#define HDMI_IDENTIFIER 0x000C03 +#define AUDIO_BLOCK 0x01 #define VENDOR_BLOCK 0x03 +#define EDID_BASIC_AUDIO (1 << 6) + /** - * drm_detect_hdmi_monitor - detect whether monitor is hdmi. - * @edid: monitor EDID information - * - * Parse the CEA extension according to CEA-861-B. - * Return true if HDMI, false if not or unknown. + * Search EDID for CEA extension block. */ -bool drm_detect_hdmi_monitor(struct edid *edid) +static u8 *drm_find_cea_extension(struct edid *edid) { - char *edid_ext = NULL; - int i, hdmi_id; - int start_offset, end_offset; - bool is_hdmi = false; + u8 *edid_ext = NULL; + int i;
/* No EDID or EDID extensions */ if (edid == NULL || edid->extensions == 0) - goto end; + return NULL;
/* Find CEA extension */ for (i = 0; i < edid->extensions; i++) { - edid_ext = (char *)edid + EDID_LENGTH * (i + 1); - /* This block is CEA extension */ - if (edid_ext[0] == 0x02) + edid_ext = (u8 *)edid + EDID_LENGTH * (i + 1); + if (edid_ext[0] == CEA_EXT) break; }
if (i == edid->extensions) + return NULL; + + return edid_ext; +} + +/** + * drm_detect_hdmi_monitor - detect whether monitor is hdmi. + * @edid: monitor EDID information + * + * Parse the CEA extension according to CEA-861-B. + * Return true if HDMI, false if not or unknown. + */ +bool drm_detect_hdmi_monitor(struct edid *edid) +{ + u8 *edid_ext; + int i, hdmi_id; + int start_offset, end_offset; + bool is_hdmi = false; + + edid_ext = drm_find_cea_extension(edid); + if (!edid_ext) goto end;
/* Data block offset in CEA extension block */ @@ -1326,6 +1343,53 @@ end: EXPORT_SYMBOL(drm_detect_hdmi_monitor);
/** + * drm_detect_monitor_audio - check monitor audio capability + * + * Monitor should have CEA extension block. + * If monitor has 'basic audio', but no CEA audio blocks, it's 'basic + * audio' only. If there is any audio extension block and supported + * audio format, assume at least 'basic audio' support, even if 'basic + * audio' is not defined in EDID. + * + */ +bool drm_detect_monitor_audio(struct edid *edid) +{ + u8 *edid_ext; + int i, j; + bool has_audio = false; + int start_offset, end_offset; + + edid_ext = drm_find_cea_extension(edid); + if (!edid_ext) + goto end; + + has_audio = ((edid_ext[3] & EDID_BASIC_AUDIO) != 0); + + if (has_audio) { + DRM_DEBUG_KMS("Monitor has basic audio support\n"); + goto end; + } + + /* Data block offset in CEA extension block */ + start_offset = 4; + end_offset = edid_ext[2]; + + for (i = start_offset; i < end_offset; + i += ((edid_ext[i] & 0x1f) + 1)) { + if ((edid_ext[i] >> 5) == AUDIO_BLOCK) { + has_audio = true; + for (j = 1; j < (edid_ext[i] & 0x1f); j += 3) + DRM_DEBUG_KMS("CEA audio format %d\n", + (edid_ext[i + j] >> 3) & 0xf); + goto end; + } + } +end: + return has_audio; +} +EXPORT_SYMBOL(drm_detect_monitor_audio); + +/** * drm_add_edid_modes - add modes from EDID data, if available * @connector: connector we're probing * @edid: edid data diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h index c9f3cc5..284ca90 100644 --- a/include/drm/drm_crtc.h +++ b/include/drm/drm_crtc.h @@ -754,6 +754,7 @@ extern int drm_mode_gamma_get_ioctl(struct drm_device *dev, extern int drm_mode_gamma_set_ioctl(struct drm_device *dev, void *data, struct drm_file *file_priv); extern bool drm_detect_hdmi_monitor(struct edid *edid); +extern bool drm_detect_monitor_audio(struct edid *edid); extern int drm_mode_page_flip_ioctl(struct drm_device *dev, void *data, struct drm_file *file_priv); extern struct drm_display_mode *drm_cvt_mode(struct drm_device *dev,