1 files changed, 79 insertions, 54 deletions

diff --git a/drivers/gpu/drm/drm_fb_helper.c b/drivers/gpu/drm/drm_fb_helper.c
index d3af098b0922..d73703a695e8 100644
--- a/drivers/gpu/drm/drm_fb_helper.c
+++ b/drivers/gpu/drm/drm_fb_helper.c
@@ -1621,6 +1621,64 @@ static bool drm_fb_pixel_format_equal(const struct fb_var_screeninfo *var_1,
                var_1->transp.msb_right == var_2->transp.msb_right;
 }
 
+static void drm_fb_helper_fill_pixel_fmt(struct fb_var_screeninfo *var,
+                                         u8 depth)
+{
+        switch (depth) {
+        case 8:
+                var->red.offset = 0;
+                var->green.offset = 0;
+                var->blue.offset = 0;
+                var->red.length = 8; /* 8bit DAC */
+                var->green.length = 8;
+                var->blue.length = 8;
+                var->transp.offset = 0;
+                var->transp.length = 0;
+                break;
+        case 15:
+                var->red.offset = 10;
+                var->green.offset = 5;
+                var->blue.offset = 0;
+                var->red.length = 5;
+                var->green.length = 5;
+                var->blue.length = 5;
+                var->transp.offset = 15;
+                var->transp.length = 1;
+                break;
+        case 16:
+                var->red.offset = 11;
+                var->green.offset = 5;
+                var->blue.offset = 0;
+                var->red.length = 5;
+                var->green.length = 6;
+                var->blue.length = 5;
+                var->transp.offset = 0;
+                break;
+        case 24:
+                var->red.offset = 16;
+                var->green.offset = 8;
+                var->blue.offset = 0;
+                var->red.length = 8;
+                var->green.length = 8;
+                var->blue.length = 8;
+                var->transp.offset = 0;
+                var->transp.length = 0;
+                break;
+        case 32:
+                var->red.offset = 16;
+                var->green.offset = 8;
+                var->blue.offset = 0;
+                var->red.length = 8;
+                var->green.length = 8;
+                var->blue.length = 8;
+                var->transp.offset = 24;
+                var->transp.length = 8;
+                break;
+        default:
+                break;
+        }
+}
+
 /**
  * drm_fb_helper_check_var - implementation for &fb_ops.fb_check_var
  * @var: screeninfo to check
@@ -1632,9 +1690,14 @@ int drm_fb_helper_check_var(struct fb_var_screeninfo *var,
         struct drm_fb_helper *fb_helper = info->par;
         struct drm_framebuffer *fb = fb_helper->fb;
 
-        if (var->pixclock != 0 || in_dbg_master())
+        if (in_dbg_master())
                 return -EINVAL;
 
+        if (var->pixclock != 0) {
+                DRM_DEBUG("fbdev emulation doesn't support changing the pixel clock, value of pixclock is ignored\n");
+                var->pixclock = 0;
+        }
+
         if ((drm_format_info_block_width(fb->format, 0) > 1) ||
             (drm_format_info_block_height(fb->format, 0) > 1))
                 return -EINVAL;
@@ -1655,6 +1718,20 @@ int drm_fb_helper_check_var(struct fb_var_screeninfo *var,
         }
 
         /*
+         * Workaround for SDL 1.2, which is known to be setting all pixel format
+         * fields values to zero in some cases. We treat this situation as a
+         * kind of "use some reasonable autodetected values".
+         */
+        if (!var->red.offset     && !var->green.offset    &&
+            !var->blue.offset    && !var->transp.offset   &&
+            !var->red.length     && !var->green.length    &&
+            !var->blue.length    && !var->transp.length   &&
+            !var->red.msb_right  && !var->green.msb_right &&
+            !var->blue.msb_right && !var->transp.msb_right) {
+                drm_fb_helper_fill_pixel_fmt(var, fb->format->depth);
+        }
+
+        /*
          * drm fbdev emulation doesn't support changing the pixel format at all,
          * so reject all pixel format changing requests.
          */
@@ -1967,59 +2044,7 @@ void drm_fb_helper_fill_var(struct fb_info *info, struct drm_fb_helper *fb_helpe
         info->var.yoffset = 0;
         info->var.activate = FB_ACTIVATE_NOW;
 
-        switch (fb->format->depth) {
-        case 8:
-                info->var.red.offset = 0;
-                info->var.green.offset = 0;
-                info->var.blue.offset = 0;
-                info->var.red.length = 8; /* 8bit DAC */
-                info->var.green.length = 8;
-                info->var.blue.length = 8;
-                info->var.transp.offset = 0;
-                info->var.transp.length = 0;
-                break;
-        case 15:
-                info->var.red.offset = 10;
-                info->var.green.offset = 5;
-                info->var.blue.offset = 0;
-                info->var.red.length = 5;
-                info->var.green.length = 5;
-                info->var.blue.length = 5;
-                info->var.transp.offset = 15;
-                info->var.transp.length = 1;
-                break;
-        case 16:
-                info->var.red.offset = 11;
-                info->var.green.offset = 5;
-                info->var.blue.offset = 0;
-                info->var.red.length = 5;
-                info->var.green.length = 6;
-                info->var.blue.length = 5;
-                info->var.transp.offset = 0;
-                break;
-        case 24:
-                info->var.red.offset = 16;
-                info->var.green.offset = 8;
-                info->var.blue.offset = 0;
-                info->var.red.length = 8;
-                info->var.green.length = 8;
-                info->var.blue.length = 8;
-                info->var.transp.offset = 0;
-                info->var.transp.length = 0;
-                break;
-        case 32:
-                info->var.red.offset = 16;
-                info->var.green.offset = 8;
-                info->var.blue.offset = 0;
-                info->var.red.length = 8;
-                info->var.green.length = 8;
-                info->var.blue.length = 8;
-                info->var.transp.offset = 24;
-                info->var.transp.length = 8;
-                break;
-        default:
-                break;
-        }
+        drm_fb_helper_fill_pixel_fmt(&info->var, fb->format->depth);
 
         info->var.xres = fb_width;
         info->var.yres = fb_height;