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drm/sun4i: hdmi: Check for unset best_parent in sun4i_tmds_determine_rate

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It is possible that if there is no exact rate match and
"rounded = clk_hw_round_rate(parent, ideal)" gives high enough values
(e.g. if rounded is 2 * ideal) that the condition
"abs(rate - rounded / i) < abs(rate - best_parent / best_div)" is never
met and best_parent is never set. This results in req->rate and
req->best_parent_rate being assigned 0.

To avoid this, we set best_parent to the first calculated rate if it is
unset. The sun4i_tmds_calc_divider function already has a similar check.

Fixes: 9c5681011a ("drm/sun4i: Add HDMI support")
Signed-off-by: Jonathan Liu <net147@gmail.com>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180109020323.11852-2-net147@gmail.com
This commit is contained in:
Jonathan Liu 2018-01-09 13:03:21 +11:00 committed by Maxime Ripard
parent b0bb222440
commit 111f4c3309
1 changed files with 1 additions and 1 deletions
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2
drivers/gpu/drm/sun4i/sun4i_hdmi_tmds_clk.c
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@ -102,7 +102,7 @@ static int sun4i_tmds_determine_rate(struct clk_hw *hw,
goto out;
}
if (abs(rate - rounded / i) <
if (!best_parent || abs(rate - rounded / i) <
abs(rate - best_parent / best_div)) {
best_parent = rounded;
best_div = i;