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Subject[PATCH 1/3] drm: Separate EDID Header Check from EDID Block Check
Date
From: Thomas Reim <rdratlos@yahoo.co.uk>

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 2.35, 2.38 and 3.0

Signed-off-by: Thomas Reim <rdratlos@yahoo.co.uk>
---
drivers/gpu/drm/drm_edid.c | 24 ++++++++++++++++++------
include/drm/drm_crtc.h | 1 +
2 files changed, 19 insertions(+), 6 deletions(-)
diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index 0929219..1bbb85b 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -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");
diff --git a/include/drm/drm_crtc.h b/include/drm/drm_crtc.h
index 33d12f8..0ec3687 100644
--- a/include/drm/drm_crtc.h
+++ b/include/drm/drm_crtc.h
@@ -802,6 +802,7 @@ 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);
--
1.7.1


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