(Sorry if I'm spawning a very old thread here). After all this time I have been patching my kernels to workaround [0][1] [0] <https://bugs.debian.org/cgi-bin/bugreport.cgi?bugb4549> [1] <https://bugs.freedesktop.org/show_bug.cgi?id7040> Some time ago I found [2] and today I finally solved the problem. [2] <http://www.blaicher.com/2012/06/howto-fixing-a-broken-edid-eeprom-with-a-bus-pirate-v4/> Some stuff I learned: the kernel does ignores checksums mismatches by 8... in the positive side! My mismatch was exactly -1, ie, 255. I have been modifying the original patch to workaround this since 2011. I'm attaching my last patch in case someone else needs it. It does adds a kernel parameter to ignore edid mismatches. Kinds regards, Lisandro. -- Theory and practice sometimes clash. And when that happens, theory loses. Every single time. Linus Benedict Torvalds. Lisandro Damián Nicanor Pérez Meyer http://perezmeyer.com.ar/ http://perezmeyer.blogspot.com/
diff --git a/drivers/gpu/drm/drm_edid.c b/drivers/gpu/drm/drm_edid.c
index 830f750..773c5d0 100644
--- a/drivers/gpu/drm/drm_edid.c
+++ b/drivers/gpu/drm/drm_edid.c
@@ -1018,6 +1018,9 @@ bool drm_edid_block_valid(u8 *raw_edid, int block, bool print_bad_edid)
}
}
+ if (!drm_edid_strict)
+ return 1;
+
for (i = 0; i < EDID_LENGTH; i++)
csum += raw_edid[i];
if (csum) {
@@ -2021,7 +2024,7 @@ do_inferred_modes(struct detailed_timing *timing, void *c)
closure->modes += drm_dmt_modes_for_range(closure->connector,
closure->edid,
timing);
-
+
if (!version_greater(closure->edid, 1, 1))
return; /* GTF not defined yet */
@@ -2258,7 +2261,7 @@ do_cvt_mode(struct detailed_timing *timing, void *c)
static int
add_cvt_modes(struct drm_connector *connector, struct edid *edid)
-{
+{
struct detailed_mode_closure closure = {
connector, edid, 0, 0, 0
};
diff --git a/drivers/gpu/drm/drm_stub.c b/drivers/gpu/drm/drm_stub.c
index 39d8645..487a6ef 100644
--- a/drivers/gpu/drm/drm_stub.c
+++ b/drivers/gpu/drm/drm_stub.c
@@ -49,6 +49,9 @@ EXPORT_SYMBOL(drm_vblank_offdelay);
unsigned int drm_timestamp_precision = 20; /* Default to 20 usecs. */
EXPORT_SYMBOL(drm_timestamp_precision);
+int drm_edid_strict = 1; /* 0 to disable strict edid conformance */
+EXPORT_SYMBOL(drm_edid_strict);
+
/*
* Default to use monotonic timestamps for wait-for-vblank and page-flip
* complete events.
@@ -63,12 +66,14 @@ MODULE_PARM_DESC(rnodes, "Enable experimental render nodes API");
MODULE_PARM_DESC(vblankoffdelay, "Delay until vblank irq auto-disable [msecs]");
MODULE_PARM_DESC(timestamp_precision_usec, "Max. error on timestamps [usecs]");
MODULE_PARM_DESC(timestamp_monotonic, "Use monotonic timestamps");
+MODULE_PARM_DESC(edid_strict, "Strict EDID checks (0 = disable)");
module_param_named(debug, drm_debug, int, 0600);
module_param_named(rnodes, drm_rnodes, int, 0600);
module_param_named(vblankoffdelay, drm_vblank_offdelay, int, 0600);
module_param_named(timestamp_precision_usec, drm_timestamp_precision, int, 0600);
module_param_named(timestamp_monotonic, drm_timestamp_monotonic, int, 0600);
+module_param_named(edid_strict, drm_edid_strict, int, 0600);
struct idr drm_minors_idr;
diff --git a/include/drm/drmP.h b/include/drm/drmP.h
index b46fb45..b86d239 100644
--- a/include/drm/drmP.h
+++ b/include/drm/drmP.h
@@ -1462,6 +1462,7 @@ extern unsigned int drm_rnodes;
extern unsigned int drm_vblank_offdelay;
extern unsigned int drm_timestamp_precision;
extern unsigned int drm_timestamp_monotonic;
+extern int drm_edid_strict;
extern struct class *drm_class;
extern struct dentry *drm_debugfs_root;
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