drm/sun4i: Create minimal multipliers and dividers

The various outputs the TCON can provide have different constraints on the
dotclock divider. Let's make them configurable by the various mode_set
functions.

Reviewed-by: Chen-Yu Tsai <wens@csie.org>
Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Link: https://patchwork.freedesktop.org/patch/msgid/92ff5881c8f8674056d34458b2f264cd48d4e136.1513854122.git-series.maxime.ripard@free-electrons.com

3 files changed, 11 insertions, 3 deletions

diff --git a/drivers/gpu/drm/sun4i/sun4i_dotclock.c b/drivers/gpu/drm/sun4i/sun4i_dotclock.c
index d401156490f3..023f39bda633 100644
--- a/drivers/gpu/drm/sun4i/sun4i_dotclock.c
+++ b/drivers/gpu/drm/sun4i/sun4i_dotclock.c
@@ -17,8 +17,9 @@
 #include "sun4i_dotclock.h"
 
 struct sun4i_dclk {
-        struct clk_hw   hw;
-        struct regmap   *regmap;
+        struct clk_hw           hw;
+        struct regmap           *regmap;
+        struct sun4i_tcon       *tcon;
 };
 
 static inline struct sun4i_dclk *hw_to_dclk(struct clk_hw *hw)
@@ -73,11 +74,13 @@ 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)
 {
+        struct sun4i_dclk *dclk = hw_to_dclk(hw);
+        struct sun4i_tcon *tcon = dclk->tcon;
         unsigned long best_parent = 0;
         u8 best_div = 1;
         int i;
 
-        for (i = 6; i <= 127; i++) {
+        for (i = tcon->dclk_min_div; i <= tcon->dclk_max_div; i++) {
                 unsigned long ideal = rate * i;
                 unsigned long rounded;
 
@@ -167,6 +170,7 @@ int sun4i_dclk_create(struct device *dev, struct sun4i_tcon *tcon)
         dclk = devm_kzalloc(dev, sizeof(*dclk), GFP_KERNEL);
         if (!dclk)
                 return -ENOMEM;
+        dclk->tcon = tcon;
 
         init.name = clk_name;
         init.ops = &sun4i_dclk_ops;
diff --git a/drivers/gpu/drm/sun4i/sun4i_tcon.c b/drivers/gpu/drm/sun4i/sun4i_tcon.c
index a1ed462c2430..41d325c0420f 100644
--- a/drivers/gpu/drm/sun4i/sun4i_tcon.c
+++ b/drivers/gpu/drm/sun4i/sun4i_tcon.c
@@ -177,6 +177,8 @@ static void sun4i_tcon0_mode_set_rgb(struct sun4i_tcon *tcon,
         u8 clk_delay;
         u32 val = 0;
 
+        tcon->dclk_min_div = 6;
+        tcon->dclk_max_div = 127;
         sun4i_tcon0_mode_set_common(tcon, mode);
 
         /* Adjust clock delay */
diff --git a/drivers/gpu/drm/sun4i/sun4i_tcon.h b/drivers/gpu/drm/sun4i/sun4i_tcon.h
index 839266a38505..bd3ad7684870 100644
--- a/drivers/gpu/drm/sun4i/sun4i_tcon.h
+++ b/drivers/gpu/drm/sun4i/sun4i_tcon.h
@@ -169,6 +169,8 @@ struct sun4i_tcon {
 
         /* Pixel clock */
         struct clk                      *dclk;
+        u8                              dclk_max_div;
+        u8                              dclk_min_div;
 
         /* Reset control */
         struct reset_control            *lcd_rst;