display: Use dcpext0 for HDMI out on t8112/t6020/t6021

dcpext0 behaves like dcp on M1* devices and can sleep after display
init. This has the advantage of not breaking macOS when starting with an
initialized display.
dcpext* are according to Apple's tech specs slightly more powerful than
dcp. They are advertised as 6K at 60Hz while dcp seems to be limited to
5K at 60Hz.

Signed-off-by: Janne Grunau <j@jannau.net>

src/dcp.c

@@ -204,12 +204,7 @@ out_free:
 
 int dcp_shutdown(dcp_dev_t *dcp, bool sleep)
 {
-    if (dcp->dptx_ep) {
-        if (sleep) {
-            printf("DCP: dcp_shutdown(sleep=true) is broken with dptx-port, quiesce instead\n");
-            sleep = false;
-        }
-    }
+    /* dcp/dcp0 on desktop M2 and M2 Pro/Max devices do not wake from sleep */
     dcp_system_shutdown(dcp->system_ep);
     dcp_dptx_shutdown(dcp->dptx_ep);
     dcp_dpav_shutdown(dcp->dpav_ep);

src/dcp.h

@@ -19,6 +19,7 @@ typedef struct {
     const char dptx_phy[24];
     const char dp2hdmi_gpio[24];
     const char pmgr_dev[24];
+    const char dcp_alias[8];
     u32 dcp_index;
     u8 num_dptxports;
     u8 die;

src/display.c

@@ -37,41 +37,49 @@ static const display_config_t display_config_m1 = {
     .dcp_dart = "/arm-io/dart-dcp",
     .disp_dart = "/arm-io/dart-disp0",
     .pmgr_dev = "DISP0_CPU0",
+    .dcp_alias = "dcp",
 };
 
+#define USE_DCPEXT 1
+
 static const display_config_t display_config_m2 = {
+#if USE_DCPEXT
+    .dcp = "/arm-io/dcpext",
+    .dcp_dart = "/arm-io/dart-dcpext",
+    .disp_dart = "/arm-io/dart-dispext0",
+    .pmgr_dev = "DISPEXT_CPU0",
+    .dcp_alias = "dcpext",
+    .dcp_index = 1,
+#else
     .dcp = "/arm-io/dcp",
     .dcp_dart = "/arm-io/dart-dcp",
     .disp_dart = "/arm-io/dart-disp0",
     .dp2hdmi_gpio = "/arm-io/dp2hdmi-gpio",
     .dptx_phy = "/arm-io/dptx-phy",
     .pmgr_dev = "DISP0_CPU0",
+    .dcp_alias = "dcp",
     .dcp_index = 0,
+#endif
+    .dp2hdmi_gpio = "/arm-io/dp2hdmi-gpio",
+    .dptx_phy = "/arm-io/dptx-phy",
     .num_dptxports = 2,
 };
 
-#define T6020_T6021_USE_DCPEXT 255
-
 static const display_config_t display_config_m2_pro_max = {
-#if T6020_T6021_USE_DCPEXT == 0
+#if USE_DCPEXT
     .dcp = "/arm-io/dcpext0",
     .dcp_dart = "/arm-io/dart-dcpext0",
     .disp_dart = "/arm-io/dart-dispext0",
     .pmgr_dev = "DISPEXT0_CPU0",
+    .dcp_alias = "dcpext0",
     .dcp_index = 1,
     .num_dptxports = 2,
-#elif T6020_T6021_USE_DCPEXT == 1
-    .dcp = "/arm-io/dcpext1",
-    .dcp_dart = "/arm-io/dart-dcpext1",
-    .disp_dart = "/arm-io/dart-dispext1",
-    .pmgr_dev = "DISPEXT1_CPU0",
-    .dcp_index = 2,
-    .num_dptxports = 2,
 #else
     .dcp = "/arm-io/dcp0",
     .dcp_dart = "/arm-io/dart-dcp0",
     .disp_dart = "/arm-io/dart-disp0",
     .pmgr_dev = "DISP0_CPU0",
+    .dcp_alias = "dcp",
     .dcp_index = 0,
     .num_dptxports = 1,
 #endif
@@ -86,6 +94,7 @@ static const display_config_t display_config_m2_ultra = {
     .dp2hdmi_gpio = "/arm-io/dp2hdmi-gpio1",
     .dptx_phy = "/arm-io/lpdptx-phy1",
     .pmgr_dev = "DISPEXT4_CPU0",
+    .dcp_alias = "dcpext4",
     .dcp_index = 1,
     .num_dptxports = 2,
     .die = 1,
@@ -222,6 +231,18 @@ static uintptr_t display_map_fb(uintptr_t iova, u64 paddr, u64 size)
     return iova;
 }
 
+const display_config_t *display_get_config(void)
+{
+    if (adt_is_compatible(adt, 0, "J473AP"))
+        return &display_config_m2;
+    else if (adt_is_compatible(adt, 0, "J474sAP") || adt_is_compatible(adt, 0, "J475cAP"))
+        return &display_config_m2_pro_max;
+    else if (adt_is_compatible(adt, 0, "J180dAP") || adt_is_compatible(adt, 0, "J475dAP"))
+        return &display_config_m2_ultra;
+    else
+        return &display_config_m1;
+}
+
 int display_start_dcp(void)
 {
     if (iboot)
@@ -232,14 +253,7 @@ int display_start_dcp(void)
     return 0;
 #endif
 
-    const display_config_t *disp_cfg = &display_config_m1;
-
-    if (adt_is_compatible(adt, 0, "J473AP"))
-        disp_cfg = &display_config_m2;
-    else if (adt_is_compatible(adt, 0, "J474sAP") || adt_is_compatible(adt, 0, "J475cAP"))
-        disp_cfg = &display_config_m2_pro_max;
-    else if (adt_is_compatible(adt, 0, "J180dAP") || adt_is_compatible(adt, 0, "J475dAP"))
-        disp_cfg = &display_config_m2_ultra;
+    const display_config_t *disp_cfg = display_get_config();
 
     display_is_dptx = !!disp_cfg->dptx_phy[0];
 

src/display.h

@@ -3,6 +3,7 @@
 #ifndef DISPLAY_H
 #define DISPLAY_H
 
+#include "dcp.h"
 #include "types.h"
 
 typedef enum _dcp_shutdown_mode {
@@ -17,5 +18,6 @@ int display_init(void);
 int display_start_dcp(void);
 int display_configure(const char *config);
 void display_shutdown(dcp_shutdown_mode mode);
+const display_config_t *display_get_config(void);
 
 #endif

src/kboot.c

@@ -8,6 +8,7 @@
 #include "clk.h"
 #include "dapf.h"
 #include "devicetree.h"
+#include "display.h"
 #include "exception.h"
 #include "firmware.h"
 #include "isp.h"
@@ -1774,7 +1775,6 @@ static int dt_set_display(void)
      * they are missing. */
 
     int ret = 0;
-    char dcp_alias[8] = "dcp";
 
     if (!fdt_node_check_compatible(dt, 0, "apple,t8103")) {
         ret = dt_carveout_reserved_regions("dcp", "disp0", "disp0_piodma",
@@ -1818,9 +1818,7 @@ static int dt_set_display(void)
         if (ret)
             return ret;
     } else if (!fdt_node_check_compatible(dt, 0, "apple,t6022")) {
-        // Set dcp_alias to "dcpext4" on  M2 Ultra, cmp. display.c
-        strncpy(dcp_alias, "dcpext4", sizeof(dcp_alias));
-        dcp_alias[sizeof(dcp_alias) - 1] = '\0';
+        /* noop */
     } else {
         printf("FDT: unknown compatible, skip display reserved-memory setup\n");
         return 0;
@@ -1838,7 +1836,9 @@ static int dt_set_display(void)
         !fdt_node_check_compatible(dt, 0, "apple,t6022"))
         dt_reserve_dcpext_firmware();
 
-    return dt_vram_reserved_region(dcp_alias, "disp0");
+    const display_config_t *disp_cfg = display_get_config();
+
+    return dt_vram_reserved_region(disp_cfg->dcp_alias, "disp0");
 }
 
 static int dt_set_sio_fwdata(void)