2015-04-10 19:14:54

by Sergej Sawazki

Subject: [PATCH v3] clk: si5351: fix .round_rate for multisynth 6-7

The divider calculation for multisynth 6 and 7 differs from the
calculation for multisynth 0-5.

For MS6 and MS7, set MSx_P1 directly, MSx_P1 = divide value
[AN619, p. 6].

Referenced document:
[AN619] Manually Generating an Si5351 Register Map, Rev. 0.4

Signed-off-by: Sergej Sawazki <[email protected]>
---
drivers/clk/clk-si5351.c | 21 +++++++++++++++++----
1 file changed, 17 insertions(+), 4 deletions(-)

diff --git a/drivers/clk/clk-si5351.c b/drivers/clk/clk-si5351.c
index 44ea107..8e90bdd 100644
--- a/drivers/clk/clk-si5351.c
+++ b/drivers/clk/clk-si5351.c
@@ -552,7 +552,8 @@ static const struct clk_ops si5351_pll_ops = {
* MSx_P2[19:0] = 128 * b - c * floor(128 * b/c) = (128*b) mod c
* MSx_P3[19:0] = c
*
- * MS[6,7] are integer (P1) divide only, P2 = 0, P3 = 0
+ * MS[6,7] are integer (P1) divide only, P1 = divide value,
+ * P2 and P3 are not applicable
*
* for 150MHz < fOUT <= 160MHz:
*
@@ -679,6 +680,16 @@ static long si5351_msynth_round_rate(struct clk_hw *hw, unsigned long rate,
c = 1;

*parent_rate = a * rate;
+ } else if (hwdata->num >= 6) {
+ /* determine the closest integer divider */
+ a = DIV_ROUND_CLOSEST(*parent_rate, rate);
+ if (a < SI5351_MULTISYNTH_A_MIN)
+ a = SI5351_MULTISYNTH_A_MIN;
+ if (a > SI5351_MULTISYNTH67_A_MAX)
+ a = SI5351_MULTISYNTH67_A_MAX;
+
+ b = 0;
+ c = 1;
} else {
unsigned long rfrac, denom;

@@ -692,9 +703,7 @@ static long si5351_msynth_round_rate(struct clk_hw *hw, unsigned long rate,
a = *parent_rate / rate;
if (a < SI5351_MULTISYNTH_A_MIN)
a = SI5351_MULTISYNTH_A_MIN;
- if (hwdata->num >= 6 && a > SI5351_MULTISYNTH67_A_MAX)
- a = SI5351_MULTISYNTH67_A_MAX;
- else if (a > SI5351_MULTISYNTH_A_MAX)
+ if (a > SI5351_MULTISYNTH_A_MAX)
a = SI5351_MULTISYNTH_A_MAX;

/* find best approximation for b/c = fVCO mod fOUT */
@@ -723,6 +732,10 @@ static long si5351_msynth_round_rate(struct clk_hw *hw, unsigned long rate,
hwdata->params.p3 = 1;
hwdata->params.p2 = 0;
hwdata->params.p1 = 0;
+ } else if (hwdata->num >= 6) {
+ hwdata->params.p3 = 0;
+ hwdata->params.p2 = 0;
+ hwdata->params.p1 = a;
} else {
hwdata->params.p3 = c;
hwdata->params.p2 = (128 * b) % c;
--
1.9.1

2015-04-11 11:01:39

by Sebastian Hesselbarth

Subject: Re: [PATCH v3] clk: si5351: fix .round_rate for multisynth 6-7

On 10.04.2015 21:14, Sergej Sawazki wrote:
> The divider calculation for multisynth 6 and 7 differs from the
> calculation for multisynth 0-5.
>
> For MS6 and MS7, set MSx_P1 directly, MSx_P1 = divide value
> [AN619, p. 6].
>
> Referenced document:
> [AN619] Manually Generating an Si5351 Register Map, Rev. 0.4
>
> Signed-off-by: Sergej Sawazki <[email protected]>

Looks good to me now,

Reviewed-by: Sebastian Hesselbarth <[email protected]>

Thanks!

> ---
> drivers/clk/clk-si5351.c | 21 +++++++++++++++++----
> 1 file changed, 17 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/clk/clk-si5351.c b/drivers/clk/clk-si5351.c
> index 44ea107..8e90bdd 100644
> --- a/drivers/clk/clk-si5351.c
> +++ b/drivers/clk/clk-si5351.c
> @@ -552,7 +552,8 @@ static const struct clk_ops si5351_pll_ops = {
> * MSx_P2[19:0] = 128 * b - c * floor(128 * b/c) = (128*b) mod c
> * MSx_P3[19:0] = c
> *
> - * MS[6,7] are integer (P1) divide only, P2 = 0, P3 = 0
> + * MS[6,7] are integer (P1) divide only, P1 = divide value,
> + * P2 and P3 are not applicable
> *
> * for 150MHz < fOUT <= 160MHz:
> *
> @@ -679,6 +680,16 @@ static long si5351_msynth_round_rate(struct clk_hw *hw, unsigned long rate,
> c = 1;
>
> *parent_rate = a * rate;
> + } else if (hwdata->num >= 6) {
> + /* determine the closest integer divider */
> + a = DIV_ROUND_CLOSEST(*parent_rate, rate);
> + if (a < SI5351_MULTISYNTH_A_MIN)
> + a = SI5351_MULTISYNTH_A_MIN;
> + if (a > SI5351_MULTISYNTH67_A_MAX)
> + a = SI5351_MULTISYNTH67_A_MAX;
> +
> + b = 0;
> + c = 1;
> } else {
> unsigned long rfrac, denom;
>
> @@ -692,9 +703,7 @@ static long si5351_msynth_round_rate(struct clk_hw *hw, unsigned long rate,
> a = *parent_rate / rate;
> if (a < SI5351_MULTISYNTH_A_MIN)
> a = SI5351_MULTISYNTH_A_MIN;
> - if (hwdata->num >= 6 && a > SI5351_MULTISYNTH67_A_MAX)
> - a = SI5351_MULTISYNTH67_A_MAX;
> - else if (a > SI5351_MULTISYNTH_A_MAX)
> + if (a > SI5351_MULTISYNTH_A_MAX)
> a = SI5351_MULTISYNTH_A_MAX;
>
> /* find best approximation for b/c = fVCO mod fOUT */
> @@ -723,6 +732,10 @@ static long si5351_msynth_round_rate(struct clk_hw *hw, unsigned long rate,
> hwdata->params.p3 = 1;
> hwdata->params.p2 = 0;
> hwdata->params.p1 = 0;
> + } else if (hwdata->num >= 6) {
> + hwdata->params.p3 = 0;
> + hwdata->params.p2 = 0;
> + hwdata->params.p1 = a;
> } else {
> hwdata->params.p3 = c;
> hwdata->params.p2 = (128 * b) % c;
>