fbdev: atafb - Fix line length handling

  - Make sure par->next_line is always set (this was done for Falcon only),
    as all the text console drawing operations need a valid par->next_line,
  - Make sure fix->line_length is always set, as some userspace applications
    need it because they don't have fallback code for the case where it's zero.
Signed-off-by: NGeert Uytterhoeven <geert@linux-m68k.org>

drivers/video/atafb.c

@@ -614,7 +614,7 @@ static int tt_encode_fix(struct fb_fix_screeninfo *fix, struct atafb_par *par)
 	fix->xpanstep = 0;
 	fix->ypanstep = 1;
 	fix->ywrapstep = 0;
-	fix->line_length = 0;
+	fix->line_length = par->next_line;
 	fix->accel = FB_ACCEL_ATARIBLITT;
 	return 0;
 }
@@ -691,6 +691,7 @@ static int tt_decode_var(struct fb_var_screeninfo *var, struct atafb_par *par)
 		return -EINVAL;
 	par->yres_virtual = yres_virtual;
 	par->screen_base = screen_base + var->yoffset * linelen;
+	par->next_line = linelen;
 	return 0;
 }
 
@@ -918,7 +919,7 @@ static int falcon_encode_fix(struct fb_fix_screeninfo *fix,
 		fix->visual = FB_VISUAL_TRUECOLOR;
 		fix->xpanstep = 2;
 	}
-	fix->line_length = 0;
+	fix->line_length = par->next_line;
 	fix->accel = FB_ACCEL_ATARIBLITT;
 	return 0;
 }
@@ -1852,7 +1853,7 @@ static int stste_encode_fix(struct fb_fix_screeninfo *fix,
 		fix->ypanstep = 0;
 	}
 	fix->ywrapstep = 0;
-	fix->line_length = 0;
+	fix->line_length = par->next_line;
 	fix->accel = FB_ACCEL_ATARIBLITT;
 	return 0;
 }
@@ -1910,6 +1911,7 @@ static int stste_decode_var(struct fb_var_screeninfo *var,
 		return -EINVAL;
 	par->yres_virtual = yres_virtual;
 	par->screen_base = screen_base + var->yoffset * linelen;
+	par->next_line = linelen;
 	return 0;
 }
 
@@ -2169,7 +2171,7 @@ static int ext_encode_fix(struct fb_fix_screeninfo *fix, struct atafb_par *par)
 	fix->xpanstep = 0;
 	fix->ypanstep = 0;
 	fix->ywrapstep = 0;
-	fix->line_length = 0;
+	fix->line_length = par->next_line;
 	return 0;
 }
 
@@ -2184,6 +2186,8 @@ static int ext_decode_var(struct fb_var_screeninfo *var, struct atafb_par *par)
 	    var->xoffset > 0 ||
 	    var->yoffset > 0)
 		return -EINVAL;
+
+	par->next_line = external_xres_virtual * external_depth / 8;
 	return 0;
 }