soc/intel/cmn/gfx: Fix GFX modeset issue with dual-display

This patch fixes the redundent GFX modeset issue when a dual display
is attached (e.g. an eDP display and an HDMI display).

The issue was caused by the MBUS joining logic not considering the
display type. This patch introduces three types of display: internal,
external, and dual-display. The MBUS joining logic is then updated
to consider the display type and ensure that the correct pipes are
joined to the MBUS:

For internal-only displays, only PIPE-A is joined to the MBUS.
For external displays, no pipes are joined to the MBUS.
For dual-displays, all available pipes are joined to the MBUS.

BUG=b:284799726
TEST=Able to fix the redundent modeset issue when eDP and HDMI attached
to the google/rex.

Change-Id: Ie2a3b9f1212a9dcab2b7305078fe22ee35e7423c
Signed-off-by: Subrata Banik <subratabanik@google.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/78691
Reviewed-by: Nick Vaccaro <nvaccaro@google.com>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

1 files changed, 42 insertions, 11 deletions

diff --git a/src/soc/intel/common/block/graphics/graphics.c b/src/soc/intel/common/block/graphics/graphics.c
index 4bec7a4cc6..e744ca7f05 100644
--- a/src/soc/intel/common/block/graphics/graphics.c
+++ b/src/soc/intel/common/block/graphics/graphics.c
@@ -16,7 +16,19 @@
 #include <soc/pci_devs.h>
 #include <types.h>
 
+/* Display Type:
+*  0 - only internal display aka eDP attached
+*  1 - only external display aka HDMI/USB-C attached
+*  2 - dual display aka both internal and external display attached
+*/
+enum display_type {
+	INTERNAL_DISPLAY_ONLY,
+	EXTERNAL_DISPLAY_ONLY,
+	DUAL_DISPLAY,
+};
+
 #define GFX_MBUS_CTL		0x4438C
+#define GFX_MBUS_SEL(x)		(GFX_MBUS_CTL + (x))
 #define GFX_MBUS_JOIN		BIT(31)
 #define GFX_MBUS_HASHING_MODE	BIT(30)
 #define GFX_MBUS_JOIN_PIPE_SEL	(BIT(28) | BIT(27) | BIT(26))
@@ -69,7 +81,7 @@ static uint32_t graphics_get_ddi_func_ctrl(unsigned long reg)
  * Consider external display is present and enabled, if eDP/DDI-A is not enabled
  * and transcoder is attached to any DDI port (bits 27-30 are not zero).
  */
-static int get_external_display_status(void)
+static enum display_type get_external_display_status(void)
 {
 	/* Read the transcoder register for DDI-A (eDP) */
 	uint32_t ddi_a_func_ctrl = graphics_get_ddi_func_ctrl(TRANS_DDI_FUNC_CTL_A);
@@ -81,20 +93,27 @@ static int get_external_display_status(void)
 	 * Report no external display in both cases.
 	 */
 	if (ddi_a_func_ctrl == TRANS_DDI_PORT_NONE) {
-		return 0;
+		return INTERNAL_DISPLAY_ONLY;
 	} else {
-		if ((ddi_a_func_ctrl == TRANS_DDI_SELECT_PORT(PORT_A)) &&
-			 (ddi_b_func_ctrl == TRANS_DDI_SELECT_PORT(PORT_B))) {
+		if (ddi_a_func_ctrl == TRANS_DDI_SELECT_PORT(PORT_A) &&
+			 (ddi_b_func_ctrl == TRANS_DDI_SELECT_PORT(PORT_B)
+#if CONFIG(INTEL_GMA_VERSION_2)
+			 || ddi_b_func_ctrl == TRANS_DDI_SELECT_PORT(PORT_USB_C1)
+			 || ddi_b_func_ctrl == TRANS_DDI_SELECT_PORT(PORT_USB_C2)
+			 || ddi_b_func_ctrl == TRANS_DDI_SELECT_PORT(PORT_USB_C3)
+			 || ddi_b_func_ctrl == TRANS_DDI_SELECT_PORT(PORT_USB_C4)
+#endif
+		)) {
 			/*
 			 * Dual display detected: both DDI-A(eDP) and
 			 * DDI-B(HDMI) pipes are active
 			 */
-			return 1;
+			return DUAL_DISPLAY;
 		} else {
 			if (ddi_a_func_ctrl == TRANS_DDI_SELECT_PORT(PORT_A))
-				return 0;
+				return INTERNAL_DISPLAY_ONLY;
 			else
-				return 1;
+				return EXTERNAL_DISPLAY_ONLY;
 		}
 	}
 }
@@ -266,13 +285,25 @@ static void graphics_dev_final(struct device *dev)
 	pci_dev_request_bus_master(dev);
 
 	if (CONFIG(SOC_INTEL_GFX_MBUS_JOIN)) {
+		enum display_type type = get_external_display_status();
 		uint32_t hashing_mode = 0;  /* 2x2 */
-		uint32_t pipe_select = 0; /* None */
-		if (!get_external_display_status()) {
+		if (type == INTERNAL_DISPLAY_ONLY) {
 			hashing_mode = GFX_MBUS_HASHING_MODE; /* 1x4 */
-			pipe_select = GFX_MBUS_JOIN_PIPE_SEL; /* Pipe-A */
+			/* Only eDP pipes is joining the MBUS */
+			graphics_gtt_rmw(GFX_MBUS_SEL(PIPE_A), PIPE_A, GFX_MBUS_JOIN | hashing_mode);
+		} else if (type == DUAL_DISPLAY) {
+			/* All pipes are joining the MBUS */
+			graphics_gtt_rmw(GFX_MBUS_SEL(PIPE_A), PIPE_A, GFX_MBUS_JOIN | hashing_mode);
+			graphics_gtt_rmw(GFX_MBUS_SEL(PIPE_B), PIPE_B, GFX_MBUS_JOIN | hashing_mode);
+			graphics_gtt_rmw(GFX_MBUS_SEL(PIPE_C), PIPE_C, GFX_MBUS_JOIN | hashing_mode);
+#if CONFIG(INTEL_GMA_VERSION_2)
+			graphics_gtt_rmw(GFX_MBUS_SEL(PIPE_D), PIPE_D, GFX_MBUS_JOIN | hashing_mode);
+#endif
+		} else {
+			/* No pipe joins the MBUS */
+			graphics_gtt_rmw(GFX_MBUS_CTL, GFX_MBUS_JOIN_PIPE_SEL,
+					 GFX_MBUS_JOIN | hashing_mode);
 		}
-		graphics_gtt_rmw(GFX_MBUS_CTL, (uint32_t)(~pipe_select), GFX_MBUS_JOIN | hashing_mode);
 	}
 }