Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757431Ab3CDDow (ORCPT ); Sun, 3 Mar 2013 22:44:52 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:33157 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757343Ab3CDDos (ORCPT ); Sun, 3 Mar 2013 22:44:48 -0500 Message-Id: <20130304033710.623093483@decadent.org.uk> User-Agent: quilt/0.60-1 Date: Mon, 04 Mar 2013 03:37:38 +0000 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: akpm@linux-foundation.org, Dave Airlie Subject: [ 031/153] vgacon/vt: clear buffer attributes when we load a 512 character font (v2) In-Reply-To: <20130304033707.648729212@decadent.org.uk> X-SA-Exim-Connect-IP: 2001:470:1f08:1539:a11:96ff:fec6:70c4 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3856 Lines: 108 3.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Dave Airlie commit 2a2483072393b27f4336ab068a1f48ca19ff1c1e upstream. 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. Signed-off-by: Dave Airlie Signed-off-by: Ben Hutchings --- drivers/tty/vt/vt.c | 2 +- drivers/video/console/vgacon.c | 22 +++++++++++++++------- include/linux/vt_kern.h | 1 + 3 files changed, 17 insertions(+), 8 deletions(-) --- a/drivers/tty/vt/vt.c +++ b/drivers/tty/vt/vt.c @@ -657,7 +657,7 @@ static inline void save_screen(struct vc * Redrawing of screen */ -static void clear_buffer_attributes(struct vc_data *vc) +void clear_buffer_attributes(struct vc_data *vc) { unsigned short *p = (unsigned short *)vc->vc_origin; int count = vc->vc_screenbuf_size / 2; --- a/drivers/video/console/vgacon.c +++ b/drivers/video/console/vgacon.c @@ -1064,7 +1064,7 @@ static int vgacon_do_font_op(struct vgas 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 vgas /* 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 vgas 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; } --- a/include/linux/vt_kern.h +++ b/include/linux/vt_kern.h @@ -47,6 +47,7 @@ int con_set_cmap(unsigned char __user *c int con_get_cmap(unsigned char __user *cmap); void scrollback(struct vc_data *vc, int lines); void scrollfront(struct vc_data *vc, int lines); +void clear_buffer_attributes(struct vc_data *vc); void update_region(struct vc_data *vc, unsigned long start, int count); void redraw_screen(struct vc_data *vc, int is_switch); #define update_screen(x) redraw_screen(x, 0) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/