On 7/24/2014 7:46 PM, rafael.barba...@intel.com wrote:
From: Rafael Barbalho <rafael.barba...@intel.com>

This particular nasty presented itself while trying to register the
intelfb device (intel_fbdev.c). During the process of registering the device
the driver will disable the crtc via i9xx_crtc_disable. These will
also disable the panel using the generic mipi panel functions in
dsi_mod_vbt_generic.c. The stale MIPI generic data sequence pointers would
cause a crash within those functions. However, all of this is happening
while console_lock is held from do_register_framebuffer inside fbcon.c. Which
means that you got kernel log and just the device appearing to reboot/hang for
no apparent reason.

The fault started from the FB_EVENT_FB_REGISTERED event using the
fb_notifier_call_chain call in fbcon.c.

Cc: Shobhit Kumar <shobhit.ku...@intel.com>
Signed-off-by: Rafael Barbalho <rafael.barba...@intel.com>
---
  drivers/gpu/drm/i915/intel_bios.c | 2 +-
  1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/i915/intel_bios.c 
b/drivers/gpu/drm/i915/intel_bios.c
index 608ed30..a669550 100644
--- a/drivers/gpu/drm/i915/intel_bios.c
+++ b/drivers/gpu/drm/i915/intel_bios.c
@@ -878,7 +878,7 @@ err:

        /* error during parsing so set all pointers to null
         * because of partial parsing */
-       memset(dev_priv->vbt.dsi.sequence, 0, MIPI_SEQ_MAX);
+       memset(dev_priv->vbt.dsi.sequence, 0, 
sizeof(dev_priv->vbt.dsi.sequence));

Ouch !! This mistake hurts. This is manifesting now because the VBT probably you tested had sequences not supported by the driver. I am influencing a TLV based VBT structure design for the sequence which when done will ensure proper parsing for all that is known and unknown pointers will remain NULL. But for now

Reviewed-by: Shobhit Kumar <shobhit.ku...@intel.com>

Regards
Shobhit
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