Commit 051963d4 authored by Thomas Reim's avatar Thomas Reim Committed by Dave Airlie
Browse files

drm: Separate EDID Header Check from EDID Block Check 



    Provides function drm_edid_header_is_valid() for EDID header check
    and replaces EDID header check part of function drm_edid_block_valid()
    by a call of drm_edid_header_is_valid().
    This is a prerequisite to extend DDC probing, e. g. in function
    radeon_ddc_probe() for Radeon devices, by a central EDID header check.

    Tested for kernel 2.6.35, 2.6.38 and 3.0

Cc: <stable@kernel.org>
Signed-off-by: default avatarThomas Reim <reimth@gmail.com>
Reviewed-by: default avatarAlex Deucher <alexdeucher@gmail.com>
Acked-by: default avatarStephen Michaels <Stephen.Micheals@gmail.com>
Signed-off-by: default avatarDave Airlie <airlied@redhat.com>
parent 5037f8ac

drivers/gpu/drm/drm_edid.c

+18 −6
Original line number Diff line number Diff line
@@ -127,6 +127,23 @@ static const u8 edid_header[] = { 
	0x00, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x00

};



 /*

 * Sanity check the header of the base EDID block.  Return 8 if the header

 * is perfect, down to 0 if it's totally wrong.

 */

int drm_edid_header_is_valid(const u8 *raw_edid)

{

	int i, score = 0;



	for (i = 0; i < sizeof(edid_header); i++)

		if (raw_edid[i] == edid_header[i])

			score++;



	return score;

}

EXPORT_SYMBOL(drm_edid_header_is_valid);





/*

 * Sanity check the EDID block (base or extension).  Return 0 if the block

 * doesn't check out, or 1 if it's valid.
@@ -139,12 +156,7 @@ drm_edid_block_valid(u8 *raw_edid) 
	struct edid *edid = (struct edid *)raw_edid;



	if (raw_edid[0] == 0x00) {

		int score = 0;



		for (i = 0; i < sizeof(edid_header); i++)

			if (raw_edid[i] == edid_header[i])

				score++;



		int score = drm_edid_header_is_valid(raw_edid);

		if (score == 8) ;

		else if (score >= 6) {

			DRM_DEBUG("Fixing EDID header, your hardware may be failing\n");

include/drm/drm_crtc.h

+1 −0
Original line number Diff line number Diff line
@@ -804,6 +804,7 @@ extern struct drm_display_mode *drm_gtf_mode_complex(struct drm_device *dev, 
extern int drm_add_modes_noedid(struct drm_connector *connector,

				int hdisplay, int vdisplay);



extern int drm_edid_header_is_valid(const u8 *raw_edid);

extern bool drm_edid_is_valid(struct edid *edid);

struct drm_display_mode *drm_mode_find_dmt(struct drm_device *dev,

					   int hsize, int vsize, int fresh);

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