Re: [PATCH] drm: detect hdmi monitor by hdmi identifier (v2)

[Dave A. <ai...@li...>]

On Thu, 26 Mar 2009, Ma Ling wrote:

> Any comments ?

I merged this into my tree today, but I have to clean up another patch 
before I can push it.

Dave.
> 
> 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 <li...@in...>
> > ---
> > 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__ */
> 
> 
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