[Intel-gfx] [PATCH v3] drm/i915: Fix not finding the VBT when it overlaps with OPREGION_ASLE_EXT

[Hans de Goede]

Hi,

On 14-02-17 17:12, Jani Nikula wrote:
> From: Hans de Goede <hdegoede at redhat.com>
>
> 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.
>
> Cc: stable at vger.kernel.org
> Signed-off-by: Hans de Goede <hdegoede at redhat.com>
> Signed-off-by: Jani Nikula <jani.nikula at intel.com>
>
> ---
>
> Hans, I'm resending because for some reason our CI didn't pick this
> up. Fixed a s/one/on/ typo in the comment while at it.

Ok. Let me know if you need me to do anything to move this forward.

Regards,

Hans


> ---
>  drivers/gpu/drm/i915/intel_opregion.c | 13 ++++++++++++-
>  1 file changed, 12 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/i915/intel_opregion.c b/drivers/gpu/drm/i915/intel_opregion.c
> index f4429f67a4e3..4a862a358c70 100644
> --- a/drivers/gpu/drm/i915/intel_opregion.c
> +++ b/drivers/gpu/drm/i915/intel_opregion.c
> @@ -982,7 +982,18 @@ int intel_opregion_setup(struct drm_i915_private *dev_priv)
>  			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;
>