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[PATCH 4/4] clk: sunxi-ng: Wait for lock when using fractional mode

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  [PATCH 4/4] clk: sunxi-ng: Wait for lock when using fractional mode Jernej Skrabec <jernej.skrabec@siol.net> - 2017-07-30 18:50 +0200
    Re: [PATCH 4/4] clk: sunxi-ng: Wait for lock when using fractional mode Chen-Yu Tsai <wens@csie.org> - 2017-07-31 07:10 +0200
      Re: [PATCH 4/4] clk: sunxi-ng: Wait for lock when using fractional mode Jernej Škrabec <jernej.skrabec@siol.net> - 2017-07-31 19:20 +0200

#1699567 — [PATCH 4/4] clk: sunxi-ng: Wait for lock when using fractional mode

Currently ccu_frac_helper_set_rate() doesn't wait for a lock bit to be
set before returning. Because of that, unstable clock may be used.

Add a wait for lock in the helper function.

Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
---
 drivers/clk/sunxi-ng/ccu_frac.c | 4 +++-
 drivers/clk/sunxi-ng/ccu_frac.h | 2 +-
 drivers/clk/sunxi-ng/ccu_mult.c | 3 ++-
 drivers/clk/sunxi-ng/ccu_nm.c   | 3 ++-
 4 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/clk/sunxi-ng/ccu_frac.c b/drivers/clk/sunxi-ng/ccu_frac.c
index ff9e72dc5337..d1d168d4c4f0 100644
--- a/drivers/clk/sunxi-ng/ccu_frac.c
+++ b/drivers/clk/sunxi-ng/ccu_frac.c
@@ -85,7 +85,7 @@ unsigned long ccu_frac_helper_read_rate(struct ccu_common *common,
 
 int ccu_frac_helper_set_rate(struct ccu_common *common,
 			     struct ccu_frac_internal *cf,
-			     unsigned long rate)
+			     unsigned long rate, u32 lock)
 {
 	unsigned long flags;
 	u32 reg, sel;
@@ -106,5 +106,7 @@ int ccu_frac_helper_set_rate(struct ccu_common *common,
 	writel(reg | sel, common->base + common->reg);
 	spin_unlock_irqrestore(common->lock, flags);
 
+	ccu_helper_wait_for_lock(common, lock);
+
 	return 0;
 }
diff --git a/drivers/clk/sunxi-ng/ccu_frac.h b/drivers/clk/sunxi-ng/ccu_frac.h
index 7b1ee380156f..efe2dd6bac01 100644
--- a/drivers/clk/sunxi-ng/ccu_frac.h
+++ b/drivers/clk/sunxi-ng/ccu_frac.h
@@ -48,6 +48,6 @@ unsigned long ccu_frac_helper_read_rate(struct ccu_common *common,
 
 int ccu_frac_helper_set_rate(struct ccu_common *common,
 			     struct ccu_frac_internal *cf,
-			     unsigned long rate);
+			     unsigned long rate, u32 lock);
 
 #endif /* _CCU_FRAC_H_ */
diff --git a/drivers/clk/sunxi-ng/ccu_mult.c b/drivers/clk/sunxi-ng/ccu_mult.c
index ee5e96222cb2..12e0783caee6 100644
--- a/drivers/clk/sunxi-ng/ccu_mult.c
+++ b/drivers/clk/sunxi-ng/ccu_mult.c
@@ -114,7 +114,8 @@ static int ccu_mult_set_rate(struct clk_hw *hw, unsigned long rate,
 	if (ccu_frac_helper_has_rate(&cm->common, &cm->frac, rate)) {
 		ccu_frac_helper_enable(&cm->common, &cm->frac);
 
-		return ccu_frac_helper_set_rate(&cm->common, &cm->frac, rate);
+		return ccu_frac_helper_set_rate(&cm->common, &cm->frac,
+						rate, cm->lock);
 	} else {
 		ccu_frac_helper_disable(&cm->common, &cm->frac);
 	}
diff --git a/drivers/clk/sunxi-ng/ccu_nm.c b/drivers/clk/sunxi-ng/ccu_nm.c
index c6ba866b99d3..a32158e8f2e3 100644
--- a/drivers/clk/sunxi-ng/ccu_nm.c
+++ b/drivers/clk/sunxi-ng/ccu_nm.c
@@ -129,7 +129,8 @@ static int ccu_nm_set_rate(struct clk_hw *hw, unsigned long rate,
 
 		ccu_frac_helper_enable(&nm->common, &nm->frac);
 
-		return ccu_frac_helper_set_rate(&nm->common, &nm->frac, rate);
+		return ccu_frac_helper_set_rate(&nm->common, &nm->frac,
+						rate, nm->lock);
 	} else {
 		ccu_frac_helper_disable(&nm->common, &nm->frac);
 	}
-- 
2.13.3

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#1699688

On Mon, Jul 31, 2017 at 12:41 AM, Jernej Skrabec
<jernej.skrabec@siol.net> wrote:
> Currently ccu_frac_helper_set_rate() doesn't wait for a lock bit to be
> set before returning. Because of that, unstable clock may be used.
>
> Add a wait for lock in the helper function.
>
> Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>

Can you provide a Fixes: tag?

Otherwise this looks good.

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#1700213

Hi Chen-Yu,

Dne ponedeljek, 31. julij 2017 ob 07:02:18 CEST je Chen-Yu Tsai napisal(a):
> On Mon, Jul 31, 2017 at 12:41 AM, Jernej Skrabec
> 
> <jernej.skrabec@siol.net> wrote:
> > Currently ccu_frac_helper_set_rate() doesn't wait for a lock bit to be
> > set before returning. Because of that, unstable clock may be used.
> > 
> > Add a wait for lock in the helper function.
> > 
> > Signed-off-by: Jernej Skrabec <jernej.skrabec@siol.net>
> 
> Can you provide a Fixes: tag?

fixes: 89a3dfb78707 ("clk: sunxi-ng: Add fractional lib")

As we discussed on IRC, it is safe to call ccu_helper_wait_for_lock() even on 
platforms where lock bit is not present, since it just returns without effect.

Regards,
Jernej

> 
> Otherwise this looks good.

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