[PATCH v7 14/17] printk: Update Braille options when preferred more times

[Petr Mladek <pmladek@suse.com>]

The current behavior is not consistent when the same console driver
is preferred several times as Braille or non-Braille console.

In particular, preferred_dev_console is not updated when @brl_options
are passed. But @brl_options are stored only it is a new entry in
preferred_consoles[].

It is even more hairy because preferred_console[] entry is considered
a Braille entry only when .brl->options are defined.

Make the behavior consistent and always update pc->brl_options when
@brl_options are passed and they were not defined yet.

Signed-off-by: Petr Mladek <pmladek@suse.com>
---
 kernel/printk/braille.h |  7 ++++---
 kernel/printk/printk.c  | 12 +++++++++---
 2 files changed, 13 insertions(+), 6 deletions(-)

diff --git a/kernel/printk/braille.h b/kernel/printk/braille.h
index e9790c28027d..7a845caf4082 100644
--- a/kernel/printk/braille.h
+++ b/kernel/printk/braille.h
@@ -5,9 +5,10 @@
 #ifdef CONFIG_A11Y_BRAILLE_CONSOLE
 
 static inline void
-braille_set_options(struct preferred_console *pc, char *brl_options)
+braille_update_options(struct preferred_console *pc, char *brl_options)
 {
-	pc->brl_options = brl_options;
+	if (!pc->brl_options || !pc->brl_options[0])
+		pc->brl_options = brl_options;
 }
 
 static inline bool
@@ -35,7 +36,7 @@ _braille_unregister_console(struct console *console);
 #else
 
 static inline void
-braille_set_options(struct preferred_console *pc, char *brl_options)
+braille_update_options(struct preferred_console *pc, char *brl_options)
 {
 }
 
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 617414d419b1..d1481ae6c729 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -2647,10 +2647,16 @@ static int add_or_update_preferred_console(unsigned int i,
 	 * Historically, the preferred options are stored only by the first
 	 * caller who prefers the particular console.
 	 */
-	if (is_new_entry) {
+	if (is_new_entry)
 		pc->options = options;
-		braille_set_options(pc, brl_options);
-	}
+
+	/*
+	 * Allow to override normal console with the Braille variant,
+	 * for example when ttyS0 is preferred via SPCR brl,ttyS0
+	 * via the command line.
+	 */
+	if (brl_options)
+		braille_update_options(pc, brl_options);
 
 	if (brl_options)
 		want_braille_console = true;
-- 
2.56.0