[Bug 2079960] [NEW] [drm] ERROR Unexpected child device config size 40 (expected 39 for VBT version 256) in Ubuntu 24.04.1 and 22.04.5

[Yuri Zhang]

Public bug reported:

1. Power on SUT and install Ubuntu 22.04.5 or Ubuntu 24.04.1

2. After booting into OS, open a terminal and check system logs (dmesg
and /var/log/messages in RHEL, and /var/log/syslog in Ubuntu) to see if
there are any unexpected error/fail/warning logs.

3. There are fail and error logs for i915 and drm in dmesg and /var/log/messages and /var/log/syslog:
—
i915 0000:00:02.0: [drm] [ENCODER:235:DDI A/PHY A] failed to retrieve link info, disabling eDP
i915 0000:00:02.0: [drm] ERROR Unexpected child device config size 40 (expected 39 for VBT version 256)
—

It seems like theres a patch will check "40" child device size in
"/drivers/gpu/drm/i915/display/intel_bios.c"

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=5216ec0eeaee781ae74b79e91a270ea1873cabf5


""""""
drm/i915/bios: bump expected child device size
VBT versions since 256 have an extra byte for EFP index.

v2: Update BUILD_BUG_ON() (Matt)

Reviewed-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240226175854.287871-1-jani.nikula@intel.com
Signed-off-by: Jani Nikula <jani.nikula at intel.com>
Diffstat
-rw-r--r--	drivers/gpu/drm/i915/display/intel_bios.c	6	
-rw-r--r--	drivers/gpu/drm/i915/display/intel_vbt_defs.h	1	
2 files changed, 5 insertions, 2 deletions
diff --git a/drivers/gpu/drm/i915/display/intel_bios.c b/drivers/gpu/drm/i915/display/intel_bios.c
index fe52c06271ef05..f967ab406e353d 100644
--- a/drivers/gpu/drm/i915/display/intel_bios.c
+++ b/drivers/gpu/drm/i915/display/intel_bios.c
@@ -2740,11 +2740,13 @@ parse_general_definitions(struct drm_i915_private *i915)
 		expected_size = 37;
 	} else if (i915->display.vbt.version <= 215) {
 		expected_size = 38;
-	} else if (i915->display.vbt.version <= 250) {
+	} else if (i915->display.vbt.version <= 255) {
 		expected_size = 39;
+	} else if (i915->display.vbt.version <= 256) {
+		expected_size = 40;
 	} else {
 		expected_size = sizeof(*child);
-		BUILD_BUG_ON(sizeof(*child) < 39);
+		BUILD_BUG_ON(sizeof(*child) < 40);
 		drm_dbg(&i915->drm,
 			"Expected child device config size for VBT version %u not known; assuming %u\n",
 			i915->display.vbt.version, expected_size);

""""""

** Affects: subiquity (Ubuntu)
     Importance: Undecided
         Status: New

-- 
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https://bugs.launchpad.net/bugs/2079960

Title:
  [drm] ERROR Unexpected child device config size 40 (expected 39 for
  VBT version 256) in Ubuntu 24.04.1 and 22.04.5

Status in subiquity package in Ubuntu:
  New

Bug description:
  1. Power on SUT and install Ubuntu 22.04.5 or Ubuntu 24.04.1

  2. After booting into OS, open a terminal and check system logs (dmesg
  and /var/log/messages in RHEL, and /var/log/syslog in Ubuntu) to see
  if there are any unexpected error/fail/warning logs.

  3. There are fail and error logs for i915 and drm in dmesg and /var/log/messages and /var/log/syslog:
  —
  i915 0000:00:02.0: [drm] [ENCODER:235:DDI A/PHY A] failed to retrieve link info, disabling eDP
  i915 0000:00:02.0: [drm] ERROR Unexpected child device config size 40 (expected 39 for VBT version 256)
  —

  It seems like theres a patch will check "40" child device size in
  "/drivers/gpu/drm/i915/display/intel_bios.c"

  https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=5216ec0eeaee781ae74b79e91a270ea1873cabf5

  
  """"""
  drm/i915/bios: bump expected child device size
  VBT versions since 256 have an extra byte for EFP index.

  v2: Update BUILD_BUG_ON() (Matt)

  Reviewed-by: Ville Syrjälä <ville.syrjala at linux.intel.com>
  Link: https://patchwork.freedesktop.org/patch/msgid/20240226175854.287871-1-jani.nikula@intel.com
  Signed-off-by: Jani Nikula <jani.nikula at intel.com>
  Diffstat
  -rw-r--r--	drivers/gpu/drm/i915/display/intel_bios.c	6	
  -rw-r--r--	drivers/gpu/drm/i915/display/intel_vbt_defs.h	1	
  2 files changed, 5 insertions, 2 deletions
  diff --git a/drivers/gpu/drm/i915/display/intel_bios.c b/drivers/gpu/drm/i915/display/intel_bios.c
  index fe52c06271ef05..f967ab406e353d 100644
  --- a/drivers/gpu/drm/i915/display/intel_bios.c
  +++ b/drivers/gpu/drm/i915/display/intel_bios.c
  @@ -2740,11 +2740,13 @@ parse_general_definitions(struct drm_i915_private *i915)
   		expected_size = 37;
   	} else if (i915->display.vbt.version <= 215) {
   		expected_size = 38;
  -	} else if (i915->display.vbt.version <= 250) {
  +	} else if (i915->display.vbt.version <= 255) {
   		expected_size = 39;
  +	} else if (i915->display.vbt.version <= 256) {
  +		expected_size = 40;
   	} else {
   		expected_size = sizeof(*child);
  -		BUILD_BUG_ON(sizeof(*child) < 39);
  +		BUILD_BUG_ON(sizeof(*child) < 40);
   		drm_dbg(&i915->drm,
   			"Expected child device config size for VBT version %u not known; assuming %u\n",
   			i915->display.vbt.version, expected_size);

  """"""

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