ENGR00232660 EPDC: Wrong panel loaded at boot

The wrong EPDC panel can be loaded at boot time if the machine
board file has multiple panel entries with the same video mode
parameter values. To reproduce, select a particular panel with
u-boot kernel command line parameters, for example:
video=mxcepdcfb:XYZZY

Add panel XYZZY to arch/arm/mach-mx6/board-mx6sl_evk.c after
an existing entry. Use the same video mode parameter settings
as the existing entry. On boot, the existing panel will be loaded
instead of the XYZZY panel because it comes earlier in the list
and happens to have the same video mode parameter values.

Solution: If the video mode parameter settings specified in
the call to msc_epdc_fb_set_par() match those of the panel
already loaded by mxc_epdc_fb_probe(), don't execute a
search for a new matching panel.

Signed-off-by: Michael Minnick <michael.minnick@freescale.com>

diff --git a/drivers/video/mxc/mxc_epdc_fb.c b/drivers/video/mxc/mxc_epdc_fb.c
index 2df44041e65ccc05464b28d4a74a052cb229fdce..f3c8ea8d18ad9065de52d94115933332d1c69fe4 100644 (file)
--- a/drivers/video/mxc/mxc_epdc_fb.c
+++ b/drivers/video/mxc/mxc_epdc_fb.c
@@ -1492,7 +1492,6 @@ static int mxc_epdc_fb_set_par(struct fb_info *info)
         */
        if (!fb_data->hw_ready) {
                struct fb_videomode mode;
-               bool found_match = false;
                u32 xres_temp;
 
                fb_var_to_videomode(&mode, screeninfo);
@@ -1506,19 +1505,31 @@ static int mxc_epdc_fb_set_par(struct fb_info *info)
                        mode.yres = xres_temp;
                }
 
-               /* Match videomode against epdc modes */
-               for (i = 0; i < fb_data->pdata->num_modes; i++) {
-                       if (!fb_mode_is_equal(epdc_modes[i].vmode, &mode))
-                               continue;
-                       fb_data->cur_mode = &epdc_modes[i];
-                       found_match = true;
-                       break;
-               }
+               /*
+               * If requested video mode does not match current video
+               * mode, search for a matching panel.
+               */
+               if (fb_data->cur_mode &&
+                       !fb_mode_is_equal(fb_data->cur_mode->vmode,
+                       &mode)) {
+                       bool found_match = false;
+
+                       /* Match videomode against epdc modes */
+                       for (i = 0; i < fb_data->pdata->num_modes; i++) {
+                               if (!fb_mode_is_equal(epdc_modes[i].vmode,
+                                       &mode))
+                                       continue;
+                               fb_data->cur_mode = &epdc_modes[i];
+                               found_match = true;
+                               break;
+                       }
 
-               if (!found_match) {
-                       dev_err(fb_data->dev,
-                               "Failed to match requested video mode\n");
-                       return EINVAL;
+                       if (!found_match) {
+                               dev_err(fb_data->dev,
+                                       "Failed to match requested "
+                                       "video mode\n");
+                               return EINVAL;
+                       }
                }
 
                /* Found a match - Grab timing params */