[U-Boot] [PATCH 13/69] x86: Allow use of serial soon after relocation

[Simon Glass]

At present on x86 machines with use cache-as-RAM, the memory goes away just
before board_init_r() is called. This means that serial drivers are
no-longer unavailable, until initr_dm() it called, etc.

Any attempt to use printf() within this period will cause a hang.

To fix this, mark the serial devices as 'unavailable' when it is no-longer
available. Bring it back when serial_initialize() is called. This means that
the debug UART will be used instead for this period.

Signed-off-by: Simon Glass <sjg at chromium.org>
---

 common/board_f.c               | 7 +++++++
 drivers/serial/serial-uclass.c | 1 +
 2 files changed, 8 insertions(+)

diff --git a/common/board_f.c b/common/board_f.c
index 622093a..109025a 100644
--- a/common/board_f.c
+++ b/common/board_f.c
@@ -1096,6 +1096,13 @@ void board_init_f_r(void)
 		hang();
 
 	/*
+	 * The pre-relocation drivers may be using memory that has now gone
+	 * away. Mark serial as unavailable - this will fall back to the debug
+	 * UART if available.
+	 */
+	gd->flags &= ~GD_FLG_SERIAL_READY;
+
+	/*
 	 * U-Boot has been copied into SDRAM, the BSS has been cleared etc.
 	 * Transfer execution from Flash to RAM by calculating the address
 	 * of the in-RAM copy of board_init_r() and calling it
diff --git a/drivers/serial/serial-uclass.c b/drivers/serial/serial-uclass.c
index 1c447ff..6562be0 100644
--- a/drivers/serial/serial-uclass.c
+++ b/drivers/serial/serial-uclass.c
@@ -116,6 +116,7 @@ int serial_init(void)
 void serial_initialize(void)
 {
 	serial_find_console_or_panic();
+	gd->flags |= GD_FLG_SERIAL_READY;
 }
 
 static void _serial_putc(struct udevice *dev, char ch)
-- 
2.7.0.rc3.207.g0ac5344