drm: radeon: fix sign bug

The "error" variable is unsigned so it's never less than zero.  I
changed it to check if (freq < current_freq) directly.

"best_error" is also unsigned so "best_error - 100" could be a large
number instead of a negative.  Since "error" is unsigned it is never
less than a negative and so the cases where "best_error" is less than or
equal to 100 are false.

Signed-off-by: Dan Carpenter <error27@gmail.com>
Reviewed-by: Alex Deucher <alexdeucher@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>

diff --git a/drivers/gpu/drm/radeon/radeon_display.c b/drivers/gpu/drm/radeon/radeon_display.c
index 8154cdf..a68728d 100644 (file)
--- a/drivers/gpu/drm/radeon/radeon_display.c
+++ b/drivers/gpu/drm/radeon/radeon_display.c
@@ -558,15 +558,17 @@ static void radeon_compute_pll_legacy(struct radeon_pll *pll,
                                        current_freq = radeon_div(tmp, ref_div * post_div);
 
                                        if (pll->flags & RADEON_PLL_PREFER_CLOSEST_LOWER) {
-                                               error = freq - current_freq;
-                                               error = error < 0 ? 0xffffffff : error;
+                                               if (freq < current_freq)
+                                                       error = 0xffffffff;
+                                               else
+                                                       error = freq - current_freq;
                                        } else
                                                error = abs(current_freq - freq);
                                        vco_diff = abs(vco - best_vco);
 
                                        if ((best_vco == 0 && error < best_error) ||
                                            (best_vco != 0 &&
-                                            (error < best_error - 100 ||
+                                            ((best_error > 100 && error < best_error - 100) ||
                                              (abs(error - best_error) < 100 && vco_diff < best_vco_diff)))) {
                                                best_post_div = post_div;
                                                best_ref_div = ref_div;