[PATCH 4.9 56/63] drm/i915: Fix not finding the VBT when it overlaps with OPREGION_ASLE_EXT
From: Greg Kroah-Hartman
Date: Mon Mar 13 2017 - 05:06:38 EST
4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Hans de Goede <hdegoede@xxxxxxxxxx>
commit 998d75730b40afc218c059d811869abe9676b305 upstream.
If there is no OPREGION_ASLE_EXT then a VBT stored in mailbox #4 may
use the ASLE_EXT parts of the opregion. Adjust the vbt_size calculation
for a vbt in mailbox #4 for this.
This fixes the driver not finding the VBT on a jumper ezpad mini3
cherrytrail tablet and on a ACER SW5_017 machine.
Signed-off-by: Hans de Goede <hdegoede@xxxxxxxxxx>
Signed-off-by: Jani Nikula <jani.nikula@xxxxxxxxx>
Link: http://patchwork.freedesktop.org/patch/msgid/1487088758-30050-1-git-send-email-jani.nikula@xxxxxxxxx
(cherry picked from commit dfb65e71ea2c1d97ac373cc0587dc60b3307581a)
Signed-off-by: Jani Nikula <jani.nikula@xxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/gpu/drm/i915/intel_opregion.c | 13 ++++++++++++-
1 file changed, 12 insertions(+), 1 deletion(-)
--- a/drivers/gpu/drm/i915/intel_opregion.c
+++ b/drivers/gpu/drm/i915/intel_opregion.c
@@ -1031,7 +1031,18 @@ int intel_opregion_setup(struct drm_i915
opregion->vbt_size = vbt_size;
} else {
vbt = base + OPREGION_VBT_OFFSET;
- vbt_size = OPREGION_ASLE_EXT_OFFSET - OPREGION_VBT_OFFSET;
+ /*
+ * The VBT specification says that if the ASLE ext
+ * mailbox is not used its area is reserved, but
+ * on some CHT boards the VBT extends into the
+ * ASLE ext area. Allow this even though it is
+ * against the spec, so we do not end up rejecting
+ * the VBT on those boards (and end up not finding the
+ * LCD panel because of this).
+ */
+ vbt_size = (mboxes & MBOX_ASLE_EXT) ?
+ OPREGION_ASLE_EXT_OFFSET : OPREGION_SIZE;
+ vbt_size -= OPREGION_VBT_OFFSET;
if (intel_bios_is_valid_vbt(vbt, vbt_size)) {
DRM_DEBUG_KMS("Found valid VBT in ACPI OpRegion (Mailbox #4)\n");
opregion->vbt = vbt;