udlfb: don't switch if we are switching to the same videomode

The udlfb driver reprograms the hardware everytime the user switches the
console, that makes quite unusable when working on the console.

This patch makes the driver remember the videomode we are in and avoid
reprogramming the hardware if we switch to the same videomode.

We mask the "activate" field and the "FB_VMODE_SMOOTH_XPAN" flag when
comparing the videomode, because they cause spurious switches when
switching to and from the Xserver.

Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Cc: stable@vger.kernel.org
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>

diff --git a/drivers/video/fbdev/udlfb.c b/drivers/video/fbdev/udlfb.c
index 864e2917c27633186ed2eab558ac040effb84ba1..fa63a2e359d62a496ad21be99e27714c6cd8f42e 100644 (file)
--- a/drivers/video/fbdev/udlfb.c
+++ b/drivers/video/fbdev/udlfb.c
@@ -1041,10 +1041,24 @@ static int dlfb_ops_set_par(struct fb_info *info)
        int result;
        u16 *pix_framebuffer;
        int i;
+       struct fb_var_screeninfo fvs;
+
+       /* clear the activate field because it causes spurious miscompares */
+       fvs = info->var;
+       fvs.activate = 0;
+       fvs.vmode &= ~FB_VMODE_SMOOTH_XPAN;
+
+       if (!memcmp(&dlfb->current_mode, &fvs, sizeof(struct fb_var_screeninfo)))
+               return 0;
 
        result = dlfb_set_video_mode(dlfb, &info->var);
 
-       if ((result == 0) && (dlfb->fb_count == 0)) {
+       if (result)
+               return result;
+
+       dlfb->current_mode = fvs;
+
+       if (dlfb->fb_count == 0) {
 
                /* paint greenscreen */
 
@@ -1056,7 +1070,7 @@ static int dlfb_ops_set_par(struct fb_info *info)
                                   info->screen_base);
        }
 
-       return result;
+       return 0;
 }
 
 /* To fonzi the jukebox (e.g. make blanking changes take effect) */

diff --git a/include/video/udlfb.h b/include/video/udlfb.h
index 8a1948f3c07f1d44801cc95dd745d5e0d8997976..bc2e9cf34aa5f8cb5df3442dc29f334856d4abe3 100644 (file)
--- a/include/video/udlfb.h
+++ b/include/video/udlfb.h
@@ -56,6 +56,7 @@ struct dlfb_data {
        atomic_t bytes_identical; /* saved effort with backbuffer comparison */
        atomic_t bytes_sent; /* to usb, after compression including overhead */
        atomic_t cpu_kcycles_used; /* transpired during pixel processing */
+       struct fb_var_screeninfo current_mode;
 };
 
 #define NR_USB_REQUEST_I2C_SUB_IO 0x02