[PATCH 0/3] clk: mmp: bug fix for clk-frac

[PATCH 0/3] clk: mmp: bug fix for clk-frac

[Chao Xie]

From: Chao Xie <chao.xie@marvell.com>

When use the clk-frac type of mmp, some bugs are found.
The following 3 patches are bug fix for clk-frac

Chao Xie (3):
  clk: mmp: fix wrong mask when calculate denominator
  clk: mmp: fix the wrong calculation formula
  clk: mmp: try to use closer one when do round rate

 drivers/clk/mmp/clk-frac.c | 21 +++++++++++++--------
 1 file changed, 13 insertions(+), 8 deletions(-)

-- 
1.8.3.2

[PATCH 1/3] clk: mmp: fix wrong mask when calculate denominator

[Chao Xie]

From: Chao Xie <chao.xie@marvell.com>

The code has typo when calculate denominator. It should use
den_mask instead of num_mask.

Signed-off-by: Chao Xie <chao.xie@marvell.com>
---
 drivers/clk/mmp/clk-frac.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/clk/mmp/clk-frac.c b/drivers/clk/mmp/clk-frac.c
index 80c1dd1..f6e7691 100644
--- a/drivers/clk/mmp/clk-frac.c
+++ b/drivers/clk/mmp/clk-frac.c
@@ -64,7 +64,7 @@ static unsigned long clk_factor_recalc_rate(struct clk_hw *hw,
 	num = (val >> masks->num_shift) & masks->num_mask;
 
 	/* calculate denominator */
-	den = (val >> masks->den_shift) & masks->num_mask;
+	den = (val >> masks->den_shift) & masks->den_mask;
 
 	if (!den)
 		return 0;
-- 
1.8.3.2

[PATCH 2/3] clk: mmp: fix the wrong calculation formula

[Chao Xie]

From: Chao Xie <chao.xie@marvell.com>

The formula is numerator/denominator = Fin / (Fout * factor)
So
Fout = Fin * denominator / (numerator * factor).
Current clk_factor_round_rate and clk_factor_recalc_rate use
wrong formula. This patch will fix them.

Signed-off-by: Chao Xie <chao.xie@marvell.com>
---
 drivers/clk/mmp/clk-frac.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/drivers/clk/mmp/clk-frac.c b/drivers/clk/mmp/clk-frac.c
index f6e7691..5863a37 100644
--- a/drivers/clk/mmp/clk-frac.c
+++ b/drivers/clk/mmp/clk-frac.c
@@ -40,12 +40,12 @@ static long clk_factor_round_rate(struct clk_hw *hw, unsigned long drate,
 
 	for (i = 0; i < factor->ftbl_cnt; i++) {
 		prev_rate = rate;
-		rate = (((*prate / 10000) * factor->ftbl[i].num) /
-			(factor->ftbl[i].den * factor->masks->factor)) * 10000;
+		rate = (((*prate / 10000) * factor->ftbl[i].den) /
+			(factor->ftbl[i].num * factor->masks->factor)) * 10000;
 		if (rate > drate)
 			break;
 	}
-	if (i == 0)
+	if ((i == 0) || (i == factor->ftbl_cnt))
 		return rate;
 	else
 		return prev_rate;
@@ -85,8 +85,8 @@ static int clk_factor_set_rate(struct clk_hw *hw, unsigned long drate,
 
 	for (i = 0; i < factor->ftbl_cnt; i++) {
 		prev_rate = rate;
-		rate = (((prate / 10000) * factor->ftbl[i].num) /
-			(factor->ftbl[i].den * factor->masks->factor)) * 10000;
+		rate = (((prate / 10000) * factor->ftbl[i].den) /
+			(factor->ftbl[i].num * factor->masks->factor)) * 10000;
 		if (rate > drate)
 			break;
 	}
-- 
1.8.3.2

[PATCH 3/3] clk: mmp: try to use closer one when do round rate

[Chao Xie]

From: Chao Xie <chao.xie@marvell.com>

The orignal code will use the bigger rate between
"previous rate" and "current rate" when caculate the
rate.
In fact, hardware cares about the closest one.
So choose the closer rate between "previous rate" and
"current rate".

Signed-off-by: Chao Xie <chao.xie@marvell.com>
---
 drivers/clk/mmp/clk-frac.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/drivers/clk/mmp/clk-frac.c b/drivers/clk/mmp/clk-frac.c
index 5863a37..23a56f5 100644
--- a/drivers/clk/mmp/clk-frac.c
+++ b/drivers/clk/mmp/clk-frac.c
@@ -45,10 +45,14 @@ static long clk_factor_round_rate(struct clk_hw *hw, unsigned long drate,
 		if (rate > drate)
 			break;
 	}
-	if ((i == 0) || (i == factor->ftbl_cnt))
+	if ((i == 0) || (i == factor->ftbl_cnt)) {
 		return rate;
-	else
-		return prev_rate;
+	} else {
+		if ((drate - prev_rate) > (rate - drate))
+			return rate;
+		else
+			return prev_rate;
+	}
 }
 
 static unsigned long clk_factor_recalc_rate(struct clk_hw *hw,
-- 
1.8.3.2

[PATCH 0/3] clk: mmp: bug fix for clk-frac

[Chao Xie]

hi, Mike
How about these fix patches?

On Thu, Jan 23, 2014 at 10:47 AM, Chao Xie <chao.xie@marvell.com> wrote:
> From: Chao Xie <chao.xie@marvell.com>
>
> When use the clk-frac type of mmp, some bugs are found.
> The following 3 patches are bug fix for clk-frac
>
> Chao Xie (3):
>   clk: mmp: fix wrong mask when calculate denominator
>   clk: mmp: fix the wrong calculation formula
>   clk: mmp: try to use closer one when do round rate
>
>  drivers/clk/mmp/clk-frac.c | 21 +++++++++++++--------
>  1 file changed, 13 insertions(+), 8 deletions(-)
>
> --
> 1.8.3.2
>

[PATCH 0/3] clk: mmp: bug fix for clk-frac

[Mike Turquette]

Quoting Chao Xie (2014-01-22 18:47:39)
> From: Chao Xie <chao.xie@marvell.com>
> 
> When use the clk-frac type of mmp, some bugs are found.
> The following 3 patches are bug fix for clk-frac

Taken into clk-next!

Regards,
Mike

> 
> Chao Xie (3):
>   clk: mmp: fix wrong mask when calculate denominator
>   clk: mmp: fix the wrong calculation formula
>   clk: mmp: try to use closer one when do round rate
> 
>  drivers/clk/mmp/clk-frac.c | 21 +++++++++++++--------
>  1 file changed, 13 insertions(+), 8 deletions(-)
> 
> -- 
> 1.8.3.2
>