tgafb: fix mode setting with fbset

commit 62496658 upstream.

Mode setting in the TGA driver is broken for these reasons:

- info->fix.line_length is set just once in tgafb_init_fix function. If
  we change videomode, info->fix.line_length is not recalculated - so
  the video mode is changed but the screen is corrupted because of wrong
  info->fix.line_length.

- info->fix.smem_len is set in tgafb_init_fix to the size of the default
  video mode (640x480). If we set a higher resolution,
  info->fix.smem_len is smaller than the current screen size, preventing
  the userspace program from mapping the framebuffer.

This patch fixes it:

- info->fix.line_length initialization is moved to tgafb_set_par so that
  it is recalculated with each mode change.

- info->fix.smem_len is set to a fixed value representing the real
  amount of video ram (the values are taken from xfree86 driver).

- add a check to tgafb_check_var to prevent us from setting a videomode
  that doesn't fit into videoram.

- in tgafb_register, tgafb_init_fix is moved upwards, to be called
  before fb_find_mode (because fb_find_mode already needs the videoram
  size set in tgafb_init_fix).
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Cc: stable@vga.kernel.org
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

drivers/video/tgafb.c

@@ -192,6 +192,8 @@ tgafb_check_var(struct fb_var_screeninfo *var, struct fb_info *info)
 
 	if (var->xres_virtual != var->xres || var->yres_virtual != var->yres)
 		return -EINVAL;
+	if (var->xres * var->yres * (var->bits_per_pixel >> 3) > info->fix.smem_len)
+		return -EINVAL;
 	if (var->nonstd)
 		return -EINVAL;
 	if (1000000000 / var->pixclock > TGA_PLL_MAX_FREQ)
@@ -272,6 +274,7 @@ tgafb_set_par(struct fb_info *info)
 	par->yres = info->var.yres;
 	par->pll_freq = pll_freq = 1000000000 / info->var.pixclock;
 	par->bits_per_pixel = info->var.bits_per_pixel;
+	info->fix.line_length = par->xres * (par->bits_per_pixel >> 3);
 
 	tga_type = par->tga_type;
 
@@ -1318,6 +1321,7 @@ tgafb_init_fix(struct fb_info *info)
 	int tga_bus_tc = TGA_BUS_TC(par->dev);
 	u8 tga_type = par->tga_type;
 	const char *tga_type_name = NULL;
+	unsigned memory_size;
 
 	switch (tga_type) {
 	case TGA_TYPE_8PLANE:
@@ -1325,21 +1329,25 @@ tgafb_init_fix(struct fb_info *info)
 			tga_type_name = "Digital ZLXp-E1";
 		if (tga_bus_tc)
 			tga_type_name = "Digital ZLX-E1";
+		memory_size = 2097152;
 		break;
 	case TGA_TYPE_24PLANE:
 		if (tga_bus_pci)
 			tga_type_name = "Digital ZLXp-E2";
 		if (tga_bus_tc)
 			tga_type_name = "Digital ZLX-E2";
+		memory_size = 8388608;
 		break;
 	case TGA_TYPE_24PLUSZ:
 		if (tga_bus_pci)
 			tga_type_name = "Digital ZLXp-E3";
 		if (tga_bus_tc)
 			tga_type_name = "Digital ZLX-E3";
+		memory_size = 16777216;
 		break;
 	default:
 		tga_type_name = "Unknown";
+		memory_size = 16777216;
 		break;
 	}
 
@@ -1351,9 +1359,8 @@ tgafb_init_fix(struct fb_info *info)
 			    ? FB_VISUAL_PSEUDOCOLOR
 			    : FB_VISUAL_DIRECTCOLOR);
 
-	info->fix.line_length = par->xres * (par->bits_per_pixel >> 3);
 	info->fix.smem_start = (size_t) par->tga_fb_base;
-	info->fix.smem_len = info->fix.line_length * par->yres;
+	info->fix.smem_len = memory_size;
 	info->fix.mmio_start = (size_t) par->tga_regs_base;
 	info->fix.mmio_len = 512;
 
@@ -1478,6 +1485,9 @@ tgafb_register(struct device *dev)
 		modedb_tga = &modedb_tc;
 		modedbsize_tga = 1;
 	}
+
+	tgafb_init_fix(info);
+
 	ret = fb_find_mode(&info->var, info,
 			   mode_option ? mode_option : mode_option_tga,
 			   modedb_tga, modedbsize_tga, NULL,
@@ -1495,7 +1505,6 @@ tgafb_register(struct device *dev)
 	}
 
 	tgafb_set_par(info);
-	tgafb_init_fix(info);
 
 	if (register_framebuffer(info) < 0) {
 		printk(KERN_ERR "tgafb: Could not register framebuffer\n");