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path: root/drivers/gpu/drm/sun4i/sun4i_dotclock.c
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Diffstat (limited to 'drivers/gpu/drm/sun4i/sun4i_dotclock.c')
-rw-r--r--drivers/gpu/drm/sun4i/sun4i_dotclock.c39
1 files changed, 35 insertions, 4 deletions
diff --git a/drivers/gpu/drm/sun4i/sun4i_dotclock.c b/drivers/gpu/drm/sun4i/sun4i_dotclock.c
index 3ff668cb463c..5b3463197c48 100644
--- a/drivers/gpu/drm/sun4i/sun4i_dotclock.c
+++ b/drivers/gpu/drm/sun4i/sun4i_dotclock.c
@@ -72,14 +72,40 @@ static unsigned long sun4i_dclk_recalc_rate(struct clk_hw *hw,
static long sun4i_dclk_round_rate(struct clk_hw *hw, unsigned long rate,
unsigned long *parent_rate)
{
- return *parent_rate / DIV_ROUND_CLOSEST(*parent_rate, rate);
+ unsigned long best_parent = 0;
+ u8 best_div = 1;
+ int i;
+
+ for (i = 6; i < 127; i++) {
+ unsigned long ideal = rate * i;
+ unsigned long rounded;
+
+ rounded = clk_hw_round_rate(clk_hw_get_parent(hw),
+ ideal);
+
+ if (rounded == ideal) {
+ best_parent = rounded;
+ best_div = i;
+ goto out;
+ }
+
+ if ((rounded < ideal) && (rounded > best_parent)) {
+ best_parent = rounded;
+ best_div = i;
+ }
+ }
+
+out:
+ *parent_rate = best_parent;
+
+ return best_parent / best_div;
}
static int sun4i_dclk_set_rate(struct clk_hw *hw, unsigned long rate,
unsigned long parent_rate)
{
struct sun4i_dclk *dclk = hw_to_dclk(hw);
- int div = DIV_ROUND_CLOSEST(parent_rate, rate);
+ u8 div = parent_rate / rate;
return regmap_update_bits(dclk->regmap, SUN4I_TCON0_DCLK_REG,
GENMASK(6, 0), div);
@@ -127,10 +153,14 @@ int sun4i_dclk_create(struct device *dev, struct sun4i_tcon *tcon)
const char *clk_name, *parent_name;
struct clk_init_data init;
struct sun4i_dclk *dclk;
+ int ret;
parent_name = __clk_get_name(tcon->sclk0);
- of_property_read_string_index(dev->of_node, "clock-output-names", 0,
- &clk_name);
+ ret = of_property_read_string_index(dev->of_node,
+ "clock-output-names", 0,
+ &clk_name);
+ if (ret)
+ return ret;
dclk = devm_kzalloc(dev, sizeof(*dclk), GFP_KERNEL);
if (!dclk)
@@ -140,6 +170,7 @@ int sun4i_dclk_create(struct device *dev, struct sun4i_tcon *tcon)
init.ops = &sun4i_dclk_ops;
init.parent_names = &parent_name;
init.num_parents = 1;
+ init.flags = CLK_SET_RATE_PARENT;
dclk->regmap = tcon->regs;
dclk->hw.init = &init;