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Commit 8fe9790d authored by Zhenyu Wang's avatar Zhenyu Wang Committed by Chris Wilson
Browse files

drm/edid: add helper function to detect monitor audio capability 



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: default avatarWu Fengguang <fengguang.wu@intel.com>
Signed-off-by: default avatarZhenyu Wang <zhenyuw@linux.intel.com>
Reviewed-by: default avatarAdam Jackson <ajax@redhat.com>
Signed-off-by: default avatarChris Wilson <chris@chris-wilson.co.uk>
parent 6d139a87

drivers/gpu/drm/drm_edid.c

+78 −14
Original line number Diff line number Diff line
@@ -1267,34 +1267,51 @@ 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 */
@@ -1324,6 +1341,53 @@ bool drm_detect_hdmi_monitor(struct edid *edid) 
}

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

include/drm/drm_crtc.h

+1 −0
Original line number Diff line number Diff line
@@ -763,6 +763,7 @@ 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,