[Intel-gfx] [PATCH] drm: detect hdmi monitor by hdmi identifier (v2)

[Ma Ling]

Any comments ?

Thanks
Ma Ling 

On Tue, 2009-03-24 at 14:31 +0800, Ma Ling wrote:
> Sometime we need to communicate with HDMI monitor by sending audio or video info frame,
> so we have to know the monitor type. However if user utilize HDMI->DVI adaptor to connect DVI monitor,
> hardware detection will incorrectly shows the monitor is HDMI. 
> HDMI spec tell us that any device containing IEEE Registration Identifier will be treated as HDMI device.
> The patch intends to detect HDMI monitor by this rule.
> 
> Signed-off-by: Ma Ling <ling.ma at intel.com>
> ---
> In this version the function will use edid info directly, instead of fetching it again,
> at same time I did some clean-up,the patch need to re-base on [PATCH] drm: read EDID extensions from monitor(v2).
>   
>  drivers/gpu/drm/drm_edid.c |   62 ++++++++++++++++++++++++++++++++++++++++++++
>  include/drm/drm_crtc.h     |    1 +
>  2 files changed, 63 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
> index a839a28..9b72fda 100644
> --- a/drivers/gpu/drm/drm_edid.c
> +++ b/drivers/gpu/drm/drm_edid.c
> @@ -677,6 +677,68 @@ struct edid *drm_get_edid(struct drm_connector *connector,
>  }
>  EXPORT_SYMBOL(drm_get_edid);
>  
> +#define HDMI_IDENTIFIER 0x000C03
> +#define VENDOR_BLOCK    0x03
> +/**
> + * 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)
> +{
> +	char *edid_ext = NULL;
> +	int i, hdmi_id, edid_ext_num;
> +	int start_offset, end_offset;
> +	bool is_hdmi = false;
> +
> +	/* No EDID or EDID extensions */
> +	if (edid == NULL || edid->extensions == 0)
> +		goto end;
> +
> +	/* Chose real EDID extension number */
> +	edid_ext_num = edid->extensions > MAX_EDID_EXT_NUM ?
> +		       MAX_EDID_EXT_NUM : edid->extensions;
> +
> +	/* Find CEA extension */
> +	for (i = 0; i < edid_ext_num; i++) {
> +		edid_ext = (char *)edid + EDID_LENGTH * (i + 1);
> +		/* This block is CEA extension */
> +		if (edid_ext[0] == 0x02)
> +			break;
> +	}
> +
> +	if (i == edid_ext_num)
> +		goto end;
> +
> +	/* Data block offset in CEA extension block */
> +	start_offset = 4;
> +	end_offset = edid_ext[2];
> +
> +	/*
> +	 * Because HDMI identifier is in Vendor Specific Block,
> +	 * search it from all data blocks of CEA extension.
> +	 */
> +	for (i = start_offset; i < end_offset;
> +		/* Increased by data block len */
> +		i += ((edid_ext[i] & 0x1f) + 1)) {
> +		/* Find vendor specific block */
> +		if ((edid_ext[i] >> 5) == VENDOR_BLOCK) {
> +			hdmi_id = edid_ext[i + 1] | (edid_ext[i + 2] << 8) |
> +				  edid_ext[i + 3] << 16;
> +			/* Find HDMI identifier */
> +			if (hdmi_id == HDMI_IDENTIFIER)
> +				is_hdmi = true;
> +			break;
> +		}
> +	}
> +
> +end:
> +	return is_hdmi;
> +}
> +EXPORT_SYMBOL(drm_detect_hdmi_monitor);
> +
>  /**
>   * drm_add_edid_modes - add modes from EDID data, if available
>   * @connector: connector we're probing
> diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
> index 5ded1ac..2d81578 100644
> --- a/include/drm/drm_crtc.h
> +++ b/include/drm/drm_crtc.h
> @@ -731,4 +731,5 @@ extern int drm_mode_gamma_get_ioctl(struct drm_device *dev,
>  				    void *data, struct drm_file *file_priv);
>  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);
>  #endif /* __DRM_CRTC_H__ */