video: msmfb: Put the partial update magic value into the fix_screen struct.

This can then be tested by userspace to see if the capability is supported.
Userspace cannot rely on that value being left in var_screen, since userspace
itself can change it.

Signed-off-by: Dima Zavin <dima@android.com>
Signed-off-by: Carl Vanderlip <carlv@codeaurora.org>
Signed-off-by: David Brown <davidb@codeaurora.org>

1 files changed, 12 insertions, 0 deletions

diff --git a/drivers/video/msm/msm_fb.c b/drivers/video/msm/msm_fb.c
index 5436aeb94456..fe5efe59d5c5 100644
--- a/drivers/video/msm/msm_fb.c
+++ b/drivers/video/msm/msm_fb.c
@@ -469,6 +469,18 @@ static void setup_fb_info(struct msmfb_info *msmfb)
         fb_info->var.yoffset = 0;
 
         if (msmfb->panel->caps & MSMFB_CAP_PARTIAL_UPDATES) {
+                /*
+                 * Set the param in the fixed screen, so userspace can't
+                 * change it. This will be used to check for the
+                 * capability.
+                 */
+                fb_info->fix.reserved[0] = 0x5444;
+                fb_info->fix.reserved[1] = 0x5055;
+
+                /*
+                 * This preloads the value so that if userspace doesn't
+                 * change it, it will be a full update
+                 */
                 fb_info->var.reserved[0] = 0x54445055;
                 fb_info->var.reserved[1] = 0;
                 fb_info->var.reserved[2] = (uint16_t)msmfb->xres |