soc/intel/cannonlake: Initialize DDI-A lane in Normal mode

Enable DDI-A (eDP) when pre-OS graphics is not Loaded or in normal mode.
This will make sure that kernel will detect eDP.

TEST=Edp should come up in normal mode.

Change-Id: I6353020f892f2d7b75997eace88b3074adc32aef
Signed-off-by: Abhay Kumar <abhay.kumar@intel.com>
Reviewed-on: https://review.coreboot.org/22799
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Subrata Banik <subrata.banik@intel.com>
Reviewed-by: Aaron Durbin <adurbin@chromium.org>

src/soc/intel/cannonlake/graphics.c

@@ -19,6 +19,7 @@
 #include <fsp/util.h>
 #include <device/device.h>
 #include <device/pci.h>
+#include <drivers/intel/gma/i915_reg.h>
 #include <drivers/intel/gma/opregion.h>
 #include <intelblocks/graphics.h>
 
@@ -27,6 +28,43 @@ uintptr_t fsp_soc_get_igd_bar(void)
 	return graphics_get_memory_base();
 }
 
+void graphics_soc_init(struct device *dev)
+{
+	uint32_t ddi_buf_ctl;
+
+	/*
+	 * Enable DDI-A (eDP) 4-lane operation if the link is not up yet.
+	 * This will allow the kernel to use 4-lane eDP links properly
+	 * if the VBIOS or GOP driver do not execute.
+	 */
+	ddi_buf_ctl = graphics_gtt_read(DDI_BUF_CTL_A);
+	if (!acpi_is_wakeup_s3() && !(ddi_buf_ctl & DDI_BUF_CTL_ENABLE)) {
+		ddi_buf_ctl |= (DDI_A_4_LANES | DDI_INIT_DISPLAY_DETECTED |
+				DDI_BUF_IS_IDLE);
+		graphics_gtt_write(DDI_BUF_CTL_A, ddi_buf_ctl);
+	}
+
+	/*
+	 * GFX PEIM module inside FSP binary is taking care of graphics
+	 * initialization based on INTEL_GMA_ADD_VBT_DATA_FILE Kconfig
+	 * option and input VBT file. Hence no need to load/execute legacy VGA
+	 * OpROM in order to initialize GFX.
+	 *
+	 * In case of non-FSP solution, SoC need to select VGA_ROM_RUN
+	 * Kconfig to perform GFX initialization through VGA OpRom.
+	 */
+	if (IS_ENABLED(CONFIG_INTEL_GMA_ADD_VBT_DATA_FILE))
+		return;
+
+	/* IGD needs to Bus Master */
+	uint32_t reg32 = pci_read_config32(dev, PCI_COMMAND);
+	reg32 |= PCI_COMMAND_MASTER | PCI_COMMAND_MEMORY | PCI_COMMAND_IO;
+	pci_write_config32(dev, PCI_COMMAND, reg32);
+
+	/* Initialize PCI device, load/execute BIOS Option ROM */
+	pci_dev_init(dev);
+}
+
 uintptr_t graphics_soc_write_acpi_opregion(struct device *device,
 		uintptr_t current, struct acpi_rsdp *rsdp)
 {