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    Subject[PATCH 4.9 56/63] drm/i915: Fix not finding the VBT when it overlaps with OPREGION_ASLE_EXT
    Date
    4.9-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Hans de Goede <hdegoede@redhat.com>

    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@redhat.com>
    Signed-off-by: Jani Nikula <jani.nikula@intel.com>
    Link: http://patchwork.freedesktop.org/patch/msgid/1487088758-30050-1-git-send-email-jani.nikula@intel.com
    (cherry picked from commit dfb65e71ea2c1d97ac373cc0587dc60b3307581a)
    Signed-off-by: Jani Nikula <jani.nikula@intel.com>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    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;

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