Fix SD pins for SKR Pro and GTR (#19047)

Marlin/src/lcd/extui/ui_api.cpp

 // At the moment, we piggy-back off the ultralcd calls, but this could be cleaned up in the future
 
 void MarlinUI::init() {
-  #if ENABLED(SDSUPPORT) && PIN_EXISTS(SD_DETECT)
-    SET_INPUT_PULLUP(SD_DETECT_PIN);
-  #endif
-
   ExtUI::onStartup();
 }
 

Marlin/src/lcd/ultralcd.cpp

 
   #endif // HAS_SHIFT_ENCODER
 
-  #if ENABLED(SDSUPPORT) && PIN_EXISTS(SD_DETECT)
-    SET_INPUT_PULLUP(SD_DETECT_PIN);
-  #endif
-
   #if HAS_ENCODER_ACTION && HAS_SLOW_BUTTONS
     slow_buttons = 0;
   #endif

Marlin/src/pins/stm32f4/pins_BTT_GTR_V1_0.h

 //#define FAN6_PIN                          PC9   // Fan6
 //#define FAN7_PIN                          PE14  // Fan7
 
+#ifndef SDCARD_CONNECTION
+  #define SDCARD_CONNECTION ONBOARD
+#endif
+
 //
-// By default the onboard SD (SPI1) is enabled
+// By default the LCD SD (SPI2) is enabled
+// Onboard SD is on a completely separate SPI bus, and requires
+// overriding pins to access.
 //
-#define CUSTOM_SPI_PINS
-#if DISABLED(CUSTOM_SPI_PINS)
+#if SD_CONNECTION_IS(LCD)
+  #define SD_DETECT_PIN                     PB10
   #define SDSS                              PB12
-#endif
-
-// HAL SPI1 pins group
-#if ENABLED(CUSTOM_SPI_PINS)
+#elif SD_CONNECTION_IS(ONBOARD)
+  // Instruct the STM32 HAL to override the default SPI pins from the variant.h file
+  #define CUSTOM_SPI_PINS
   #define SDSS                              PA4
-  #define SD_DETECT_PIN                     PC4
-  #define LCD_SDSS                          PA4
-
+  #define SS_PIN                            SDSS
   #define SCK_PIN                           PA5
   #define MISO_PIN                          PA6
   #define MOSI_PIN                          PA7
-  #define SS_PIN                            PA4   // Chip select for SD card used by Marlin
+  #define SD_DETECT_PIN                     PC4
+#elif SD_CONNECTION_IS(CUSTOM_CABLE)
+  #define "CUSTOM_CABLE is not a supported SDCARD_CONNECTION for this board"
 #endif
 
 /**
   #define BTN_ENC                           PA15
 
   #if ENABLED(CR10_STOCKDISPLAY)
-
     #define LCD_PINS_RS                     PG6
 
     #define BTN_EN1                         PC10
     #undef BOARD_ST7920_DELAY_2
     #undef BOARD_ST7920_DELAY_3
 
+  #elif ENABLED(MKS_MINI_12864)
+    #define DOGLCD_A0                       PG6
+    #define DOGLCD_CS                       PG7
+    #define BTN_EN1                         PD10
+    #define BTN_EN2                         PH10
+
+    #if SD_CONNECTION_IS(ONBOARD)
+      #define SOFTWARE_SPI
+    #endif
   #else
 
     #define LCD_PINS_RS                     PA8
     #define BTN_EN1                         PD10
     #define BTN_EN2                         PH10
 
-    #if DISABLED(CUSTOM_SPI_PINS)
-      #define SD_DETECT_PIN                 PB10
-      #define LCD_SDSS                      PB12
-    #endif
-
     #define LCD_PINS_ENABLE                 PC10
     #define LCD_PINS_D4                     PG8
 
     #if ENABLED(FYSETC_MINI_12864)
       #define DOGLCD_CS                     PC10
       #define DOGLCD_A0                     PA8
+
+      #if SD_CONNECTION_IS(ONBOARD)
+        #define SOFTWARE_SPI
+      #endif
+
       //#define LCD_BACKLIGHT_PIN           -1
       #define LCD_RESET_PIN                 PG8   // Must be high or open for LCD to operate normally.
       #if EITHER(FYSETC_MINI_12864_1_2, FYSETC_MINI_12864_2_0)
     #endif
   #endif
 
-  //#define DOGLCD_CS                       PB12
-  //#define DOGLCD_A0                       PA8
-  //#define LCD_PINS_DC                     PB14
-  //#define DOGLCD_MOSI                     PB15
-
 #endif // HAS_SPI_LCD
 
 #undef TP

Marlin/src/pins/stm32f4/pins_BTT_SKR_PRO_common.h

 // Onboard SD card
 // Must use soft SPI because Marlin's default hardware SPI is tied to LCD's EXP2
 //
-#if SD_CONNECTION_IS(ONBOARD)
-  #define SOFTWARE_SPI                            // Use soft SPI for onboard SD
+#if SD_CONNECTION_IS(LCD)
+  #define SD_DETECT_PIN                     PF12
+  #define SDSS                              PB12
+#elif SD_CONNECTION_IS(ONBOARD)
+  // The SKR Pro's ONBOARD SD interface is on SPI1.
+  // Due to a pull resistor on the clock line, it needs to use SPI Data Mode 3 to
+  // function with Hardware SPI. This is not currently configurable in the HAL,
+  // so force Software SPI to work around this issue.
+  #define SOFTWARE_SPI
   #define SDSS                              PA4
   #define SCK_PIN                           PA5
   #define MISO_PIN                          PA6
   #define MOSI_PIN                          PB5
+  #define SD_DETECT_PIN                     PB11
+#elif SD_CONNECTION_IS(CUSTOM_CABLE)
+  #define "CUSTOM_CABLE is not a supported SDCARD_CONNECTION for this board"
 #endif
 
 /**
 #if HAS_SPI_LCD
   #define BEEPER_PIN                        PG4
   #define BTN_ENC                           PA8
-  #if SD_CONNECTION_IS(LCD)
-    #define SDSS                            PB12  // Uses default hardware SPI for LCD's SD
-  #endif
 
   #if ENABLED(CR10_STOCKDISPLAY)
     #define LCD_PINS_RS                     PG6
   #elif ENABLED(MKS_MINI_12864)
     #define DOGLCD_A0                       PG6
     #define DOGLCD_CS                       PG3
-
+    #define BTN_EN1                         PG10
+    #define BTN_EN2                         PF11
   #else
 
     #define LCD_PINS_RS                     PD10
 
     #define BTN_EN1                         PG10
     #define BTN_EN2                         PF11
-    #define SD_DETECT_PIN                   PF12
-
-    #define LCD_SDSS                        PB12
 
     #define LCD_PINS_ENABLE                 PD11
     #define LCD_PINS_D4                     PG2

Marlin/src/sd/cardreader.cpp

   // Disable autostart until card is initialized
   autostart_index = -1;
 
+  #if ENABLED(SDSUPPORT) && PIN_EXISTS(SD_DETECT)
+    SET_INPUT_PULLUP(SD_DETECT_PIN);
+  #endif
+  
   #if PIN_EXISTS(SDPOWER)
     OUT_WRITE(SDPOWER_PIN, HIGH); // Power the SD reader
   #endif