tree 3eb13d88444e14f91b95a6dbd34f403ffad47ed1
parent 5bb7dc4e050b79390037a931681c6fbce639a052
author Maulik V Vaghela <maulik.v.vaghela@intel.com> 1623218780 +0530
committer Tim Wawrzynczak <twawrzynczak@chromium.org> 1625157407 +0000

drivers/intel/gma: Move extended VBT just below opregion

Currently the flow for opregion init is as below:
1. Allocate memory for opregion first (cbmem_add(opregion))
2. Check if VBT size > 6 KiB (this requires extended VBT support)
3. In case of extended VBT requirement, we allocate another chunk
   of memory which is equal to size of VBT (cbmem_add(extended_vbt))
4. Pass physical address pointer to OS via RVDA

We can optimize the above flow to allocate single chunk of memory by
checking VBT size in earlier step. The new optimized flow for opregion
init is as below:
1. Check if VBT size > 6 KiB (this requires extended VBT support)
2. In case of extended VBT requirement, total memory to be allocated
   is calculated as sizeof(opregion) + sizeof (extended_vbt)
   In case where VBT size is < 6 KiB, total memory requirement would
   be equal to sizeof(opregion)
3. Based on above calculation, allocate single chunk of memory based on
   total size.

This will also be helpful for the case of virtualization where guest
users don't have access to physical address and when it needs relative
address of VBT compared to absolute address.

In case of opregion 2.1 spec, we need to pass relative address of
VBT from opregion base in RVDA. This optimization will help in meeting
this requirement since relative address of extended VBT is easy to get.
This change will ensure that it meets opregion specification
requirement and will be compatible with future versions as well.

BUG=b:190019970
BRANCH=None
TEST=check the address of extended VBT region and address is coming
correctly.

Change-Id: Ic0e255df63145409096b0b9312c6c51c05f49931
Signed-off-by: Maulik V Vaghela <maulik.v.vaghela@intel.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/55341
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>
Reviewed-by: Tim Wawrzynczak <twawrzynczak@chromium.org>