From 2a2483072393b27f4336ab068a1f48ca19ff1c1e Mon Sep 17 00:00:00 2001 From: Dave Airlie Date: Thu, 24 Jan 2013 14:14:19 +1000 Subject: vgacon/vt: clear buffer attributes when we load a 512 character font (v2) When we switch from 256->512 byte font rendering mode, it means the current contents of the screen is being reinterpreted. The bit that holds the high bit of the 9-bit font, may have been previously set, and thus the new font misrenders. The problem case we see is grub2 writes spaces with the bit set, so it ends up with data like 0x820, which gets reinterpreted into 0x120 char which the font translates into G with a circumflex. This flashes up on screen at boot and is quite ugly. A current side effect of this patch though is that any rendering on the screen changes color to a slightly darker color, but at least the screen no longer corrupts. v2: as suggested by hpa, always clear the attribute space, whether we are are going to or from 512 chars. Cc: stable@vger.kernel.org Signed-off-by: Dave Airlie --- drivers/video/console/vgacon.c | 22 +++++++++++++++------- 1 file changed, 15 insertions(+), 7 deletions(-) (limited to 'drivers/video') diff --git a/drivers/video/console/vgacon.c b/drivers/video/console/vgacon.c index d449a74..5855d17 100644 --- a/drivers/video/console/vgacon.c +++ b/drivers/video/console/vgacon.c @@ -1064,7 +1064,7 @@ static int vgacon_do_font_op(struct vgastate *state,char *arg,int set,int ch512) unsigned short video_port_status = vga_video_port_reg + 6; int font_select = 0x00, beg, i; char *charmap; - + bool clear_attribs = false; if (vga_video_type != VIDEO_TYPE_EGAM) { charmap = (char *) VGA_MAP_MEM(colourmap, 0); beg = 0x0e; @@ -1169,12 +1169,6 @@ static int vgacon_do_font_op(struct vgastate *state,char *arg,int set,int ch512) /* if 512 char mode is already enabled don't re-enable it. */ if ((set) && (ch512 != vga_512_chars)) { - /* attribute controller */ - for (i = 0; i < MAX_NR_CONSOLES; i++) { - struct vc_data *c = vc_cons[i].d; - if (c && c->vc_sw == &vga_con) - c->vc_hi_font_mask = ch512 ? 0x0800 : 0; - } vga_512_chars = ch512; /* 256-char: enable intensity bit 512-char: disable intensity bit */ @@ -1185,8 +1179,22 @@ static int vgacon_do_font_op(struct vgastate *state,char *arg,int set,int ch512) it means, but it works, and it appears necessary */ inb_p(video_port_status); vga_wattr(state->vgabase, VGA_AR_ENABLE_DISPLAY, 0); + clear_attribs = true; } raw_spin_unlock_irq(&vga_lock); + + if (clear_attribs) { + for (i = 0; i < MAX_NR_CONSOLES; i++) { + struct vc_data *c = vc_cons[i].d; + if (c && c->vc_sw == &vga_con) { + /* force hi font mask to 0, so we always clear + the bit on either transition */ + c->vc_hi_font_mask = 0x00; + clear_buffer_attributes(c); + c->vc_hi_font_mask = ch512 ? 0x0800 : 0; + } + } + } return 0; } -- cgit v1.1