uvesafb: fix color component length for pseudocolor modes

uvesafb incorrectly sets the length of the color fields to 6 bits for
PSEUDOCOLOR modes, even though 8 bits are always used per pixel.  Fix this
by setting the length to 8.

The switch of the DAC width from the default 6 bits to 8 bits is retained
and tracked internally in the driver, but never exposed to userspace.

Signed-off-by: Michal Januszewski <spock@gentoo.org>
Acked-by: Krzysztof Helt <krzysztof.h1@poczta.fm>
Cc: <syrjala@sci.fi>
Cc: Geert Uytterhoeven <geert.uytterhoeven@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 10 insertions, 25 deletions

diff --git a/drivers/video/uvesafb.c b/drivers/video/uvesafb.c
index 0b370aebdbfd..421770b5e6ab 100644
--- a/drivers/video/uvesafb.c
+++ b/drivers/video/uvesafb.c
@@ -55,6 +55,7 @@ static u16 maxvf	__devinitdata; /* maximum vertical frequency */
 static u16 maxhf        __devinitdata; /* maximum horizontal frequency */
 static u16 vbemode      __devinitdata; /* force use of a specific VBE mode */
 static char *mode_option __devinitdata;
+static u8  dac_width    = 6;
 
 static struct uvesafb_ktask *uvfb_tasks[UVESAFB_TASKS_MAX];
 static DEFINE_MUTEX(uvfb_lock);
@@ -303,22 +304,10 @@ static void uvesafb_setup_var(struct fb_var_screeninfo *var,
                 var->blue.offset   = 0;
                 var->transp.offset = 0;
 
-                /*
-                 * We're assuming that we can switch the DAC to 8 bits. If
-                 * this proves to be incorrect, we'll update the fields
-                 * later in set_par().
-                 */
-                if (par->vbe_ib.capabilities & VBE_CAP_CAN_SWITCH_DAC) {
-                        var->red.length    = 8;
-                        var->green.length  = 8;
-                        var->blue.length   = 8;
-                        var->transp.length = 0;
-                } else {
-                        var->red.length    = 6;
-                        var->green.length  = 6;
-                        var->blue.length   = 6;
-                        var->transp.length = 0;
-                }
+                var->red.length    = 8;
+                var->green.length  = 8;
+                var->blue.length   = 8;
+                var->transp.length = 0;
         }
 }
 
@@ -1006,7 +995,7 @@ static int uvesafb_setcolreg(unsigned regno, unsigned red, unsigned green,
                 struct fb_info *info)
 {
         struct uvesafb_pal_entry entry;
-        int shift = 16 - info->var.green.length;
+        int shift = 16 - dac_width;
         int err = 0;
 
         if (regno >= info->cmap.len)
@@ -1055,7 +1044,7 @@ static int uvesafb_setcolreg(unsigned regno, unsigned red, unsigned green,
 static int uvesafb_setcmap(struct fb_cmap *cmap, struct fb_info *info)
 {
         struct uvesafb_pal_entry *entries;
-        int shift = 16 - info->var.green.length;
+        int shift = 16 - dac_width;
         int i, err = 0;
 
         if (info->var.bits_per_pixel == 8) {
@@ -1317,13 +1306,9 @@ setmode:
                 err = uvesafb_exec(task);
                 if (err || (task->t.regs.eax & 0xffff) != 0x004f ||
                     ((task->t.regs.ebx & 0xff00) >> 8) != 8) {
-                        /*
-                         * We've failed to set the DAC palette format -
-                         * time to correct var.
-                         */
-                        info->var.red.length    = 6;
-                        info->var.green.length  = 6;
-                        info->var.blue.length   = 6;
+                        dac_width = 6;
+                } else {
+                        dac_width = 8;
                 }
         }