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drm/sun4i: hdmi: Allow using second PLL as TMDS clk parent

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On SoCs with two display pipelines, it is possible that the two
pipelines are active at the same time, with potentially incompatible
dot clocks.

Let the HDMI encoder's TMDS clock go through all of its parents when
calculating possible clock rates. This allows usage of the second video
PLL as its parent.

Signed-off-by: Chen-Yu Tsai <wens@csie.org>
Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20171010032008.682-6-wens@csie.org
This commit is contained in:
Chen-Yu Tsai 2017-10-10 11:20:02 +08:00 committed by Maxime Ripard
parent 4b1c924b1f
commit cc67ae90be
1 changed files with 25 additions and 20 deletions
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45
drivers/gpu/drm/sun4i/sun4i_hdmi_tmds_clk.c
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@ -67,11 +67,11 @@ static unsigned long sun4i_tmds_calc_divider(unsigned long rate,
static int sun4i_tmds_determine_rate(struct clk_hw *hw,
struct clk_rate_request *req)
{
struct clk_hw *parent;
struct clk_hw *parent = NULL;
unsigned long best_parent = 0;
unsigned long rate = req->rate;
int best_div = 1, best_half = 1;
int i, j;
int i, j, p;
/*
* We only consider PLL3, since the TCON is very likely to be
@ -79,32 +79,37 @@ static int sun4i_tmds_determine_rate(struct clk_hw *hw,
* clock, so we should not need to do anything.
*/
parent = clk_hw_get_parent_by_index(hw, 0);
if (!parent)
return -EINVAL;
for (p = 0; p < clk_hw_get_num_parents(hw); p++) {
parent = clk_hw_get_parent_by_index(hw, p);
if (!parent)
continue;
for (i = 1; i < 3; i++) {
for (j = 1; j < 16; j++) {
unsigned long ideal = rate * i * j;
unsigned long rounded;
for (i = 1; i < 3; i++) {
for (j = 1; j < 16; j++) {
unsigned long ideal = rate * i * j;
unsigned long rounded;
rounded = clk_hw_round_rate(parent, ideal);
rounded = clk_hw_round_rate(parent, ideal);
if (rounded == ideal) {
best_parent = rounded;
best_half = i;
best_div = j;
goto out;
}
if (rounded == ideal) {
best_parent = rounded;
best_half = i;
best_div = j;
goto out;
}
if (abs(rate - rounded / i) <
abs(rate - best_parent / best_div)) {
best_parent = rounded;
best_div = i;
if (abs(rate - rounded / i) <
abs(rate - best_parent / best_div)) {
best_parent = rounded;
best_div = i;
}
}
}
}
if (!parent)
return -EINVAL;
out:
req->rate = best_parent / best_half / best_div;
req->best_parent_rate = best_parent;