---
Changes in v2:
-Check the whole string when checking for erases in putcs, instead of just
the first char
-Make dummycon_blank return 1, so that a redraw gets triggered and any text
rendered while blanked gets output so that it can trigger a deferred
takeover if one is pending
Changes in v3:
-Call WARN_CONSOLE_UNLOCKED() from fbcon_output_notifier()
-Unregister the notifier on fbcon_exit()
-Document the fbcon=nodefer commandline option in Documentation/fb/fbcon.txt
---
Documentation/fb/fbcon.txt | 7 ++++
drivers/video/console/Kconfig | 11 +++++
drivers/video/console/dummycon.c | 67 +++++++++++++++++++++++++----
drivers/video/fbdev/core/fbcon.c | 72 ++++++++++++++++++++++++++++++++
include/linux/console.h | 5 +++
5 files changed, 154 insertions(+), 8 deletions(-)
diff --git a/Documentation/fb/fbcon.txt b/Documentation/fb/fbcon.txt
index 79c22d096bbc..d4d642e1ce9c 100644
--- a/Documentation/fb/fbcon.txt
+++ b/Documentation/fb/fbcon.txt
@@ -155,6 +155,13 @@ C. Boot options
used by text. By default, this area will be black. The 'color' value
is an integer number that depends on the framebuffer driver being used.
+6. fbcon=nodefer
+
+ If the kernel is compiled with deferred fbcon takeover support, normally
+ the framebuffer contents, left in place by the firmware/bootloader, will
+ be preserved until there actually is some text is output to the console.
+ This option causes fbcon to bind immediately to the fbdev device.
+
C. Attaching, Detaching and Unloading
Before going on how to attach, detach and unload the framebuffer console, an
diff --git a/drivers/video/console/Kconfig b/drivers/video/console/Kconfig
index 4110ba7d7ca9..e91edef98633 100644
--- a/drivers/video/console/Kconfig
+++ b/drivers/video/console/Kconfig
@@ -150,6 +150,17 @@ config FRAMEBUFFER_CONSOLE_ROTATION
such that other users of the framebuffer will remain normally
oriented.
+config FRAMEBUFFER_CONSOLE_DEFERRED_TAKEOVER
+ bool "Framebuffer Console Deferred Takeover"
+ depends on FRAMEBUFFER_CONSOLE=y && DUMMY_CONSOLE=y
+ help
+ If enabled this defers the framebuffer console taking over the
+ console from the dummy console until the first text is displayed on
+ the console. This is useful in combination with the "quiet" kernel
+ commandline option to keep the framebuffer contents initially put up
+ by the firmware in place, rather then replacing the contents with a
+ black screen as soon as fbcon loads.
+
config STI_CONSOLE
bool "STI text console"
depends on PARISC && HAS_IOMEM
diff --git a/drivers/video/console/dummycon.c b/drivers/video/console/dummycon.c
index f2eafe2ed980..45ad925ad5f8 100644
--- a/drivers/video/console/dummycon.c
+++ b/drivers/video/console/dummycon.c
@@ -26,6 +26,65 @@
#define DUMMY_ROWS CONFIG_DUMMY_CONSOLE_ROWS
#endif
+#ifdef CONFIG_FRAMEBUFFER_CONSOLE_DEFERRED_TAKEOVER
+/* These are both protected by the console_lock */
+static RAW_NOTIFIER_HEAD(dummycon_output_nh);
+static bool dummycon_putc_called;
+
+void dummycon_register_output_notifier(struct notifier_block *nb)
+{
+ raw_notifier_chain_register(&dummycon_output_nh, nb);
+
+ if (dummycon_putc_called)
+ nb->notifier_call(nb, 0, NULL);
+}
+
+void dummycon_unregister_output_notifier(struct notifier_block *nb)
+{
+ raw_notifier_chain_unregister(&dummycon_output_nh, nb);
+}
+
+static void dummycon_putc(struct vc_data *vc, int c, int ypos, int xpos)
+{
+ dummycon_putc_called = true;
+ raw_notifier_call_chain(&dummycon_output_nh, 0, NULL);
+}
+
+static void dummycon_putcs(struct vc_data *vc, const unsigned short *s,
+ int count, int ypos, int xpos)
+{
+ int i;
+
+ if (!dummycon_putc_called) {
+ /* Ignore erases */
+ for (i = 0 ; i < count; i++) {
+ if (s[i] != vc->vc_video_erase_char)
+ break;
+ }
+ if (i == count)
+ return;
+
+ dummycon_putc_called = true;
+ }
+
+ raw_notifier_call_chain(&dummycon_output_nh, 0, NULL);
+}
+
+static int dummycon_blank(struct vc_data *vc, int blank, int mode_switch)
+{
+ /* Redraw, so that we get putc(s) for output done while blanked */
+ return 1;
+}
+#else
+static void dummycon_putc(struct vc_data *vc, int c, int ypos, int xpos) { }
+static void dummycon_putcs(struct vc_data *vc, const unsigned short *s,
+ int count, int ypos, int xpos) { }
+static int dummycon_blank(struct vc_data *vc, int blank, int mode_switch)
+{
+ return 0;
+}
+#endif
+
static const char *dummycon_startup(void)
{
return "dummy device";
@@ -44,9 +103,6 @@ static void dummycon_init(struct vc_data *vc, int init)
static void dummycon_deinit(struct vc_data *vc) { }
static void dummycon_clear(struct vc_data *vc, int sy, int sx, int height,
int width) { }
-static void dummycon_putc(struct vc_data *vc, int c, int ypos, int xpos) { }
-static void dummycon_putcs(struct vc_data *vc, const unsigned short *s,
- int count, int ypos, int xpos) { }
static void dummycon_cursor(struct vc_data *vc, int mode) { }
static bool dummycon_scroll(struct vc_data *vc, unsigned int top,
@@ -61,11 +117,6 @@ static int dummycon_switch(struct vc_data *vc)
return 0;
}
-static int dummycon_blank(struct vc_data *vc, int blank, int mode_switch)
-{
- return 0;
-}
-
static int dummycon_font_set(struct vc_data *vc, struct console_font *font,
unsigned int flags)
{
diff --git a/drivers/video/fbdev/core/fbcon.c b/drivers/video/fbdev/core/fbcon.c
index cd8d52a967aa..5fb156bdcf4e 100644
--- a/drivers/video/fbdev/core/fbcon.c
+++ b/drivers/video/fbdev/core/fbcon.c
@@ -129,6 +129,12 @@ static inline void fbcon_map_override(void)
}
#endif /* CONFIG_FRAMEBUFFER_CONSOLE_DETECT_PRIMARY */
+#ifdef CONFIG_FRAMEBUFFER_CONSOLE_DEFERRED_TAKEOVER
+static bool deferred_takeover = true;
+#else
+#define deferred_takeover false
+#endif
+
/* font data */
static char fontname[40];
@@ -499,6 +505,12 @@ static int __init fb_console_setup(char *this_opt)
margin_color = simple_strtoul(options, &options, 0);
continue;
}
+#ifdef CONFIG_FRAMEBUFFER_CONSOLE_DEFERRED_TAKEOVER
+ if (!strcmp(options, "nodefer")) {
+ deferred_takeover = false;
+ continue;
+ }
+#endif
}
return 1;
}
@@ -3100,6 +3112,9 @@ static int fbcon_fb_unregistered(struct fb_info *info)
WARN_CONSOLE_UNLOCKED();
+ if (deferred_takeover)
+ return 0;
+
idx = info->node;
for (i = first_fb_vc; i <= last_fb_vc; i++) {
if (con2fb_map[i] == idx)
@@ -3140,6 +3155,13 @@ static void fbcon_remap_all(int idx)
WARN_CONSOLE_UNLOCKED();
+ if (deferred_takeover) {
+ for (i = first_fb_vc; i <= last_fb_vc; i++)
+ con2fb_map_boot[i] = idx;
+ fbcon_map_override();
+ return;
+ }
+
for (i = first_fb_vc; i <= last_fb_vc; i++)
set_con2fb_map(i, idx, 0);
@@ -3191,6 +3213,11 @@ static int fbcon_fb_registered(struct fb_info *info)
idx = info->node;
fbcon_select_primary(info);
+ if (deferred_takeover) {
+ pr_info("fbcon: Deferring console take-over\n");
+ return 0;
+ }
+
if (info_idx == -1) {
for (i = first_fb_vc; i <= last_fb_vc; i++) {
if (con2fb_map_boot[i] == idx) {
@@ -3566,8 +3593,46 @@ static int fbcon_init_device(void)
return 0;
}
+#ifdef CONFIG_FRAMEBUFFER_CONSOLE_DEFERRED_TAKEOVER
+static struct notifier_block fbcon_output_nb;
+
+static int fbcon_output_notifier(struct notifier_block *nb,
+ unsigned long action, void *data)
+{
+ int i;
+
+ WARN_CONSOLE_UNLOCKED();
+
+ pr_info("fbcon: Taking over console\n");
+
+ dummycon_unregister_output_notifier(&fbcon_output_nb);
+ deferred_takeover = false;
+ logo_shown = FBCON_LOGO_DONTSHOW;
+
+ for (i = 0; i < FB_MAX; i++) {
+ if (registered_fb[i])
+ fbcon_fb_registered(registered_fb[i]);
+ }
+
+ return NOTIFY_OK;
+}
+
+static void fbcon_register_output_notifier(void)
+{
+ fbcon_output_nb.notifier_call = fbcon_output_notifier;
+ dummycon_register_output_notifier(&fbcon_output_nb);
+}
+#else
+static inline void fbcon_register_output_notifier(void) {}
+#endif
+
static void fbcon_start(void)
{
+ if (deferred_takeover) {
+ fbcon_register_output_notifier();
+ return;
+ }
+
if (num_registered_fb) {
int i;
@@ -3594,6 +3659,13 @@ static void fbcon_exit(void)
if (fbcon_has_exited)
return;
+#ifdef CONFIG_FRAMEBUFFER_CONSOLE_DEFERRED_TAKEOVER
+ if (deferred_takeover) {
+ dummycon_unregister_output_notifier(&fbcon_output_nb);
+ deferred_takeover = false;
+ }
+#endif
+
kfree((void *)softback_buf);
softback_buf = 0UL;
diff --git a/include/linux/console.h b/include/linux/console.h
index dfd6b0e97855..f59f3dbca65c 100644
--- a/include/linux/console.h
+++ b/include/linux/console.h
@@ -21,6 +21,7 @@ struct console_font_op;
struct console_font;
struct module;
struct tty_struct;
+struct notifier_block;
/*
* this is what the terminal answers to a ESC-Z or csi0c query.
@@ -220,4 +221,8 @@ static inline bool vgacon_text_force(void) { return false; }
extern void console_init(void);
+/* For deferred console takeover */
+void dummycon_register_output_notifier(struct notifier_block *nb);
+void dummycon_unregister_output_notifier(struct notifier_block *nb);
+
#endif /* _LINUX_CONSOLE_H */
--
2.17.1
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