[Intel-gfx] [RFC 0/1] converging intel igfx and dgfx opregion

[Anshuman Gupta]

     +---------+                            +---------+
     |         |                            |         |
     |  igfx   |                            |  dgfx   |
     |         |                            |         |
     +----+----+                            +----+----+
          |                                      |
          |                                      |
          v                                      v
+---------+-----------+        +-----------------+----------------+
|                     |        |                                  |
| intel_get_asls_opreg|        |  intel_get_{spi,pci}_oprom_opreg |
|                     |        |                                  |
+------+--------------+        +------------------+---------------+
       |                                          |
       |                                          |
       |       +---------------------------+      |
       |       |                           |      |
       +------->   intel_opregion_setup    +<-----+
               |                           |
               +---------------------------+
 
i915 requires igx and dgfx converging interface for intel opregion setup and
extracting the vbt from opregion (mailbox #3 or mailbox #4).
 
dgfx uses standrd oprom to store opregion image and CSS image.
CSS image is used for oprom signature verification and opregion image stores
VBT and other stuff.

This is the RFC proposal to start a discussion to get the opreg for igfx and
dgfx separately and have a converging function intel_opregion_setup to get the
vbt and setup the opregion.

dgfx can get the oprom by pci or spi interfaces, earlier in past there were
some BIOS related issues, which has erased PCI oprom mappings due which pci_map_rom
has failed to get the oprom.  Let's first read the oprom by PCI interface and in case
of failure fall back to SPI interface.

Requesting community to provide suggestion and feedback on above proposal.    

Thanks,
Anshuman Gupta.
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2.26.2