From: Heinrich Schuchardt <xypron.glpk@gmx.de>
Date: Sun, 22 Dec 2019 07:15:55 +0000 (+0000)
Subject: efi_loader: clear screen should move cursor to home
X-Git-Url: http://git.dujemihanovic.xyz/img/static/git-favicon.png?a=commitdiff_plain;h=b0ad9b5b2a60583dc44a171d7dfdaac1b4518aa7;p=u-boot.git

efi_loader: clear screen should move cursor to home

On a VT100 terminal <ESC>[2J should be enough to both clear the whole
screen and set the cursor to position (1, 1). But the Linux console does
not behave like this. So send an extra <ESC>[H. For reference see the
console_codes(4) man page.

Add a function description.

Signed-off-by: Heinrich Schuchardt <xypron.glpk@gmx.de>
---

diff --git a/lib/efi_loader/efi_console.c b/lib/efi_loader/efi_console.c
index 218f7caa12..8494044799 100644
--- a/lib/efi_loader/efi_console.c
+++ b/lib/efi_loader/efi_console.c
@@ -360,12 +360,26 @@ static efi_status_t EFIAPI efi_cout_set_attribute(
 	return EFI_EXIT(EFI_SUCCESS);
 }
 
+/**
+ * efi_cout_clear_screen() - clear screen
+ *
+ * This function implements the ClearScreen service of the
+ * EFI_SIMPLE_TEXT_OUTPUT_PROTOCOL. See the Unified Extensible Firmware
+ * Interface (UEFI) specification for details.
+ *
+ * @this:	pointer to the protocol instance
+ * Return:	status code
+ */
 static efi_status_t EFIAPI efi_cout_clear_screen(
 			struct efi_simple_text_output_protocol *this)
 {
 	EFI_ENTRY("%p", this);
 
-	printf(ESC"[2J");
+	/*
+	 * The Linux console wants both a clear and a home command. The video
+	 * uclass does not support <ESC>[H without coordinates, yet.
+	 */
+	printf(ESC "[2J" ESC "[1;1H");
 	efi_con_mode.cursor_column = 0;
 	efi_con_mode.cursor_row = 0;