[media] v4l2-dv-timings: fix overflow in gtf timings calculation

[firefly-linux-kernel-4.4.55.git] / drivers / media / v4l2-core / v4l2-dv-timings.c

diff --git a/drivers/media/v4l2-core/v4l2-dv-timings.c b/drivers/media/v4l2-core/v4l2-dv-timings.c
index 37f0d6f89878dcc1fef79dafaf884528d20b9d77..5792192bce6ccd3c14cf9ec01cdced4fbeb0dcc3 100644 (file)
--- a/drivers/media/v4l2-core/v4l2-dv-timings.c
+++ b/drivers/media/v4l2-core/v4l2-dv-timings.c
@@ -25,6 +25,7 @@
 #include <linux/videodev2.h>
 #include <linux/v4l2-dv-timings.h>
 #include <media/v4l2-dv-timings.h>
+#include <linux/math64.h>
 
 MODULE_AUTHOR("Hans Verkuil");
 MODULE_DESCRIPTION("V4L2 DV Timings Helper Functions");
@@ -554,16 +555,23 @@ bool v4l2_detect_gtf(unsigned frame_height,
        image_width = (image_width + GTF_CELL_GRAN/2) & ~(GTF_CELL_GRAN - 1);
 
        /* Horizontal */
-       if (default_gtf)
-               h_blank = ((image_width * GTF_D_C_PRIME * hfreq) -
-                                       (image_width * GTF_D_M_PRIME * 1000) +
-                       (hfreq * (100 - GTF_D_C_PRIME) + GTF_D_M_PRIME * 1000) / 2) /
-                       (hfreq * (100 - GTF_D_C_PRIME) + GTF_D_M_PRIME * 1000);
-       else
-               h_blank = ((image_width * GTF_S_C_PRIME * hfreq) -
-                                       (image_width * GTF_S_M_PRIME * 1000) +
-                       (hfreq * (100 - GTF_S_C_PRIME) + GTF_S_M_PRIME * 1000) / 2) /
-                       (hfreq * (100 - GTF_S_C_PRIME) + GTF_S_M_PRIME * 1000);
+       if (default_gtf) {
+               u64 num;
+               u32 den;
+
+               num = ((image_width * GTF_D_C_PRIME * (u64)hfreq) -
+                     ((u64)image_width * GTF_D_M_PRIME * 1000));
+               den = hfreq * (100 - GTF_D_C_PRIME) + GTF_D_M_PRIME * 1000;
+               h_blank = div_u64((num + (den >> 1)), den);
+       } else {
+               u64 num;
+               u32 den;
+
+               num = ((image_width * GTF_S_C_PRIME * (u64)hfreq) -
+                     ((u64)image_width * GTF_S_M_PRIME * 1000));
+               den = hfreq * (100 - GTF_S_C_PRIME) + GTF_S_M_PRIME * 1000;
+               h_blank = div_u64((num + (den >> 1)), den);
+       }
 
        h_blank = ((h_blank + GTF_CELL_GRAN) / (2 * GTF_CELL_GRAN)) *
                  (2 * GTF_CELL_GRAN);