fbcon can deal with vc_hi_font_mask (the upper 256 chars) and adjust the vc attrs dynamically when vc_hi_font_mask is changed at fbcon_init(). When the vc_hi_font_mask is set, it remaps the attrs in the existing console buffer with one bit shift up (for 9 bits), while it remaps with one bit shift down (for 8 bits) when the value is cleared. It works fine as long as the font gets updated after fbcon was initialized.

However, we hit a bizarre problem when the console is switched to another fb driver (typically from vesafb or efifb to drmfb). At switching to the new fb driver, we temporarily rebind the console to the dummy console, then rebind to the new driver. During the switching, we leave the modified attrs as is. Thus, the new fbcon takes over the old buffer as if it were to contain 8 bits chars (although the attrs are still shifted for 9 bits), and effectively this results in the yellow color texts instead of the original white color, as found in the bugzilla entry below.

An easy fix for this is to re-adjust the attrs before leaving the fbcon at con_deinit callback. Since the code to adjust the attrs is already present in the current fbcon code, in this patch, we simply factor out the relevant code, and call it from fbcon_deinit().

Bugzilla: https://bugzilla.suse.com/show_bug.cgi?id=1000619

Signed-off-by Takashi Iwai <[email protected]>

Signed-off-by Bartlomiej Zolnierkiewicz <[email protected]>

Cc Arnd Bergmann <[email protected]>

Signed-off-by Greg Kroah-Hartman <[email protected]>

---
 drivers/video/console/fbcon.c |   67 +++++++++++++++++++++++++-----------------
 1 file changed, 40 insertions(+), 27 deletions(-)

drivers/video/console/fbcon.c +40 ~~-27~~

@@ -1168,6 +1168,8 @@ static void fbcon_free_font(struct displ
 	p->userfont = 0;
 }
 
+static void set_vc_hi_font(struct vc_data *vc, bool set);
+
 static void fbcon_deinit(struct vc_data *vc)
 {
 	struct display *p = &fb_display[vc->vc_num];

@@ -1203,6 +1205,9 @@ finished:
 	if (free_font)
 		vc->vc_font.data = NULL;
 
+	if (vc->vc_hi_font_mask)
+		set_vc_hi_font(vc, false);
+
 	if (!con_is_bound(&fb_con))
 		fbcon_exit();

@@ -2439,32 +2444,10 @@ static int fbcon_get_font(struct vc_data
 	return 0;
 }
 
-static int fbcon_do_set_font(struct vc_data *vc, int w, int h,
-			     const u8 * data, int userfont)
+/* set/clear vc_hi_font_mask and update vc attrs accordingly */
+static void set_vc_hi_font(struct vc_data *vc, bool set)
 {
-	struct fb_info *info = registered_fb[con2fb_map[vc->vc_num]];
-	struct fbcon_ops *ops = info->fbcon_par;
-	struct display *p = &fb_display[vc->vc_num];
-	int resize;
-	int cnt;
-	char *old_data = NULL;
-
-	if (CON_IS_VISIBLE(vc) && softback_lines)
-		fbcon_set_origin(vc);
-
-	resize = (w != vc->vc_font.width) || (h != vc->vc_font.height);
-	if (p->userfont)
-		old_data = vc->vc_font.data;
-	if (userfont)
-		cnt = FNTCHARCNT(data);
-	else
-		cnt = 256;
-	vc->vc_font.data = (void *)(p->fontdata = data);
-	if ((p->userfont = userfont))
-		REFCOUNT(data)++;
-	vc->vc_font.width = w;
-	vc->vc_font.height = h;
-	if (vc->vc_hi_font_mask && cnt == 256) {
+	if (!set) {
 		vc->vc_hi_font_mask = 0;
 		if (vc->vc_can_do_color) {
 			vc->vc_complement_mask >>= 1;

@@ -2487,7 +2470,7 @@ static int fbcon_do_set_font(struct vc_d
 			    ((c & 0xfe00) >> 1) | (c & 0xff);
 			vc->vc_attr >>= 1;
 		}
-	} else if (!vc->vc_hi_font_mask && cnt == 512) {
+	} else {
 		vc->vc_hi_font_mask = 0x100;
 		if (vc->vc_can_do_color) {
 			vc->vc_complement_mask <<= 1;

@@ -2519,8 +2502,38 @@ static int fbcon_do_set_font(struct vc_d
 			} else
 				vc->vc_video_erase_char = c & ~0x100;
 		}
-
 	}
+}
+
+static int fbcon_do_set_font(struct vc_data *vc, int w, int h,
+			     const u8 * data, int userfont)
+{
+	struct fb_info *info = registered_fb[con2fb_map[vc->vc_num]];
+	struct fbcon_ops *ops = info->fbcon_par;
+	struct display *p = &fb_display[vc->vc_num];
+	int resize;
+	int cnt;
+	char *old_data = NULL;
+
+	if (CON_IS_VISIBLE(vc) && softback_lines)
+		fbcon_set_origin(vc);
+
+	resize = (w != vc->vc_font.width) || (h != vc->vc_font.height);
+	if (p->userfont)
+		old_data = vc->vc_font.data;
+	if (userfont)
+		cnt = FNTCHARCNT(data);
+	else
+		cnt = 256;
+	vc->vc_font.data = (void *)(p->fontdata = data);
+	if ((p->userfont = userfont))
+		REFCOUNT(data)++;
+	vc->vc_font.width = w;
+	vc->vc_font.height = h;
+	if (vc->vc_hi_font_mask && cnt == 256)
+		set_vc_hi_font(vc, false);
+	else if (!vc->vc_hi_font_mask && cnt == 512)
+		set_vc_hi_font(vc, true);
 
 	if (resize) {
 		int cols, rows;

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/fbcon-fix-vc-attr-at-deinit.patch queue-4.4/alsa-ctxfi-fix-the-incorrect-check-of-dma_set_mask-call.patch queue-4.4/alsa-hda-adding-a-group-of-pin-definition-to-fix-headset-problem.patch queue-4.4/alsa-seq-fix-racy-cell-insertions-during-snd_seq_pool_done.patch