Some NM PLLs doesn't work well when their output clock rate is set below
certain rate.

Add support for that constrain.

Signed-off-by: Jernej Skrabec <jernej.skra...@siol.net>
---
 drivers/clk/sunxi-ng/ccu_nm.c | 11 +++++++----
 drivers/clk/sunxi-ng/ccu_nm.h | 27 +++++++++++++++++++++++++++
 2 files changed, 34 insertions(+), 4 deletions(-)

diff --git a/drivers/clk/sunxi-ng/ccu_nm.c b/drivers/clk/sunxi-ng/ccu_nm.c
index a16de092bf94..7fc743c78c1b 100644
--- a/drivers/clk/sunxi-ng/ccu_nm.c
+++ b/drivers/clk/sunxi-ng/ccu_nm.c
@@ -20,7 +20,7 @@ struct _ccu_nm {
 };
 
 static void ccu_nm_find_best(unsigned long parent, unsigned long rate,
-                            struct _ccu_nm *nm)
+                            unsigned long min_rate, struct _ccu_nm *nm)
 {
        unsigned long best_rate = 0;
        unsigned long best_n = 0, best_m = 0;
@@ -30,7 +30,7 @@ static void ccu_nm_find_best(unsigned long parent, unsigned 
long rate,
                for (_m = nm->min_m; _m <= nm->max_m; _m++) {
                        unsigned long tmp_rate = parent * _n  / _m;
 
-                       if (tmp_rate > rate)
+                       if (tmp_rate > rate || tmp_rate < min_rate)
                                continue;
 
                        if ((rate - tmp_rate) < (rate - best_rate)) {
@@ -117,6 +117,9 @@ static long ccu_nm_round_rate(struct clk_hw *hw, unsigned 
long rate,
        if (nm->common.features & CCU_FEATURE_FIXED_POSTDIV)
                rate *= nm->fixed_post_div;
 
+       if (rate < nm->min_rate)
+               rate = nm->min_rate;
+
        if (ccu_frac_helper_has_rate(&nm->common, &nm->frac, rate)) {
                if (nm->common.features & CCU_FEATURE_FIXED_POSTDIV)
                        rate /= nm->fixed_post_div;
@@ -134,7 +137,7 @@ static long ccu_nm_round_rate(struct clk_hw *hw, unsigned 
long rate,
        _nm.min_m = 1;
        _nm.max_m = nm->m.max ?: 1 << nm->m.width;
 
-       ccu_nm_find_best(*parent_rate, rate, &_nm);
+       ccu_nm_find_best(*parent_rate, rate, nm->min_rate, &_nm);
        rate = *parent_rate * _nm.n / _nm.m;
 
        if (nm->common.features & CCU_FEATURE_FIXED_POSTDIV)
@@ -186,7 +189,7 @@ static int ccu_nm_set_rate(struct clk_hw *hw, unsigned long 
rate,
                                           &_nm.m, &_nm.n);
        } else {
                ccu_sdm_helper_disable(&nm->common, &nm->sdm);
-               ccu_nm_find_best(parent_rate, rate, &_nm);
+               ccu_nm_find_best(parent_rate, rate, nm->min_rate, &_nm);
        }
 
        spin_lock_irqsave(nm->common.lock, flags);
diff --git a/drivers/clk/sunxi-ng/ccu_nm.h b/drivers/clk/sunxi-ng/ccu_nm.h
index eba586b4c7d0..1d8b459c50b7 100644
--- a/drivers/clk/sunxi-ng/ccu_nm.h
+++ b/drivers/clk/sunxi-ng/ccu_nm.h
@@ -37,6 +37,7 @@ struct ccu_nm {
        struct ccu_sdm_internal         sdm;
 
        unsigned int            fixed_post_div;
+       unsigned int            min_rate;
 
        struct ccu_common       common;
 };
@@ -88,6 +89,32 @@ struct ccu_nm {
                },                                                      \
        }
 
+#define SUNXI_CCU_NM_WITH_FRAC_GATE_LOCK_MIN(_struct, _name, _parent,  \
+                                            _reg, _min_rate,           \
+                                            _nshift, _nwidth,          \
+                                            _mshift, _mwidth,          \
+                                            _frac_en, _frac_sel,       \
+                                            _frac_rate_0, _frac_rate_1,\
+                                            _gate, _lock, _flags)      \
+       struct ccu_nm _struct = {                                       \
+               .enable         = _gate,                                \
+               .lock           = _lock,                                \
+               .n              = _SUNXI_CCU_MULT(_nshift, _nwidth),    \
+               .m              = _SUNXI_CCU_DIV(_mshift, _mwidth),     \
+               .frac           = _SUNXI_CCU_FRAC(_frac_en, _frac_sel,  \
+                                                 _frac_rate_0,         \
+                                                 _frac_rate_1),        \
+               .min_rate       = _min_rate,                            \
+               .common         = {                                     \
+                       .reg            = _reg,                         \
+                       .features       = CCU_FEATURE_FRACTIONAL,       \
+                       .hw.init        = CLK_HW_INIT(_name,            \
+                                                     _parent,          \
+                                                     &ccu_nm_ops,      \
+                                                     _flags),          \
+               },                                                      \
+       }
+
 #define SUNXI_CCU_NM_WITH_GATE_LOCK(_struct, _name, _parent, _reg,     \
                                    _nshift, _nwidth,                   \
                                    _mshift, _mwidth,                   \
-- 
2.16.2

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