[coreboot-gerrit] [S] Change in coreboot[master]: soc/intel/cmn/graphics: Use pci_dev_request_bus_master for BM enabling

[Subrata Banik (Code Review)]

Subrata Banik has submitted this change. ( https://review.coreboot.org/c/coreboot/+/67273 )

Change subject: soc/intel/cmn/graphics: Use pci_dev_request_bus_master for BM enabling
......................................................................

soc/intel/cmn/graphics: Use pci_dev_request_bus_master for BM enabling

Enabling Bus Master isn't required by the hardware, so we shouldn't
need to enable it at all. However, some payloads do not set this bit
before attempting DMA transfers, which results in functionality
failure. For example: in this case, unable to see the developer screen
in Depthcharge.

In the prior IA SoC platform, FSP/GFX PEIM does the BM enabling for
the IGD BAR resources but starting with the MTL platform, it fails
to do so resulting into inability to see the Pre-OS display.

BUG=b:243919230 ([Rex] Unable to see Pre-OS display although GFX
                 PEIM Display Init is successful during AP boot)
TEST=Able to see the developer screen with eDP/HDMI while booting
the Google/Rex.

Also, this change doesn't impact the previous platforms
(ADL, TGL, CML etc.) where the BM is default enabled.

Signed-off-by: Subrata Banik 
Change-Id: I9ad9eee8379b7ea1e50224e3fabb347e5f14c25b
Reviewed-on: https://review.coreboot.org/c/coreboot/+/67273
Tested-by: build bot (Jenkins) 
Reviewed-by: Tarun Tuli 
Reviewed-by: Werner Zeh 
Reviewed-by: Angel Pons 
Reviewed-by: Wonkyu Kim 
Reviewed-by: Jamie Ryu 
Reviewed-by: Kapil Porwal 
---
M src/soc/intel/common/block/graphics/graphics.c
1 file changed, 37 insertions(+), 0 deletions(-)

Approvals:
  build bot (Jenkins): Verified
  Werner Zeh: Looks good to me, approved
  Angel Pons: Looks good to me, but someone else must approve
  Wonkyu Kim: Looks good to me, approved
  Jamie Ryu: Looks good to me, but someone else must approve
  Tarun Tuli: Looks good to me, approved
  Kapil Porwal: Looks good to me, approved

diff --git a/src/soc/intel/common/block/graphics/graphics.c b/src/soc/intel/common/block/graphics/graphics.c
index e4ef458..6b5770c 100644
--- a/src/soc/intel/common/block/graphics/graphics.c
+++ b/src/soc/intel/common/block/graphics/graphics.c
@@ -180,6 +180,7 @@
    .set_resources		= pci_dev_set_resources,
    .enable_resources	= pci_dev_enable_resources,
    .init			= gma_init,
+	.final			= pci_dev_request_bus_master,
    .ops_pci		= &pci_dev_ops_pci,
 #if CONFIG(HAVE_ACPI_TABLES)
    .acpi_fill_ssdt		= gma_generate_ssdt,