There are several issues in sun4i_tmds_determine_rate:
- doesn't check if the best match was already set before comparing it
with the enumerated parameters which could result in integer divide
by zero
- doesn't consider rate halving when determining closest match if it
can't match the requested rate exactly
- sets best_div to i which corresponds to rate halving when it should be
set to j which corresponds to the divider
Fix these issues.
Fixes: 9c5681011a0c ("drm/sun4i: Add HDMI support")
Signed-off-by: Jonathan Liu <net147@xxxxxxxxx>
---
drivers/gpu/drm/sun4i/sun4i_hdmi_tmds_clk.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/drivers/gpu/drm/sun4i/sun4i_hdmi_tmds_clk.c b/drivers/gpu/drm/sun4i/sun4i_hdmi_tmds_clk.c
index dc332ea56f6c..3ecffa52c814 100644
--- a/drivers/gpu/drm/sun4i/sun4i_hdmi_tmds_clk.c
+++ b/drivers/gpu/drm/sun4i/sun4i_hdmi_tmds_clk.c
@@ -102,10 +102,13 @@ static int sun4i_tmds_determine_rate(struct clk_hw *hw,
goto out;
}
- if (abs(rate - rounded / i) <
- abs(rate - best_parent / best_div)) {
+ if (!best_parent ||
+ abs(rate - rounded / i / j) <
+ abs(rate - best_parent / best_half /
+ best_div)) {
best_parent = rounded;
- best_div = i;
+ best_half = i;
+ best_div = j;
}
}
}
--
2.15.0
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