[PATCH] i2c: tegra: dynamically control fast clk

[PATCH] i2c: tegra: dynamically control fast clk

[Laxman Dewangan]

Tegra I2C driver enables the fast clock during initialization
and does not disable till driver removed.
Enable this clock before transfer and disable after transfer done.

Signed-off-by: Laxman Dewangan <ldewangan-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
---
This patch is on top of the clock chnages which is in Tegra sub system and
based on 
 i2c: tegra: I2_M_NOSTART functionality not supported in Tegra20
So recommend to go on tegra sub-system.

 drivers/i2c/busses/i2c-tegra.c |   35 ++++++++++++++++++++++++++++-------
 1 files changed, 28 insertions(+), 7 deletions(-)

diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c
index 554f713..24f7cee 100644
--- a/drivers/i2c/busses/i2c-tegra.c
+++ b/drivers/i2c/busses/i2c-tegra.c
@@ -362,12 +362,36 @@ static void tegra_dvc_init(struct tegra_i2c_dev *i2c_dev)
 	dvc_writel(i2c_dev, val, DVC_CTRL_REG1);
 }
 
+static inline int tegra_i2c_clock_enable(struct tegra_i2c_dev *i2c_dev)
+{
+	int ret;
+	ret = clk_prepare_enable(i2c_dev->fast_clk);
+	if (ret < 0) {
+		dev_err(i2c_dev->dev,
+			"Enabling fast clk failed, err %d\n", ret);
+		return ret;
+	}
+	ret = clk_prepare_enable(i2c_dev->div_clk);
+	if (ret < 0) {
+		dev_err(i2c_dev->dev,
+			"Enabling div clk failed, err %d\n", ret);
+		clk_disable_unprepare(i2c_dev->fast_clk);
+	}
+	return ret;
+}
+
+static inline void tegra_i2c_clock_disable(struct tegra_i2c_dev *i2c_dev)
+{
+	clk_disable_unprepare(i2c_dev->div_clk);
+	clk_disable_unprepare(i2c_dev->fast_clk);
+}
+
 static int tegra_i2c_init(struct tegra_i2c_dev *i2c_dev)
 {
 	u32 val;
 	int err = 0;
 
-	clk_prepare_enable(i2c_dev->div_clk);
+	tegra_i2c_clock_enable(i2c_dev);
 
 	tegra_periph_reset_assert(i2c_dev->div_clk);
 	udelay(2);
@@ -398,7 +422,7 @@ static int tegra_i2c_init(struct tegra_i2c_dev *i2c_dev)
 	if (tegra_i2c_flush_fifos(i2c_dev))
 		err = -ETIMEDOUT;
 
-	clk_disable_unprepare(i2c_dev->div_clk);
+	tegra_i2c_clock_disable(i2c_dev);
 
 	if (i2c_dev->irq_disabled) {
 		i2c_dev->irq_disabled = 0;
@@ -584,7 +608,7 @@ static int tegra_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[],
 		}
 	}
 
-	clk_prepare_enable(i2c_dev->clk);
+	tegra_i2c_clock_enable(i2c_dev);
 	for (i = 0; i < num; i++) {
 		enum msg_end_type end_type = MSG_END_STOP;
 		if (i < (num - 1)) {
@@ -597,7 +621,7 @@ static int tegra_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg msgs[],
 		if (ret)
 			break;
 	}
-	clk_disable_unprepare(i2c_dev->div_clk);
+	tegra_i2c_clock_disable(i2c_dev);
 	return ret ?: i;
 }
 
@@ -734,8 +758,6 @@ static int __devinit tegra_i2c_probe(struct platform_device *pdev)
 		return ret;
 	}
 
-	clk_prepare_enable(i2c_dev->fast_clk);
-
 	i2c_set_adapdata(&i2c_dev->adapter, i2c_dev);
 	i2c_dev->adapter.owner = THIS_MODULE;
 	i2c_dev->adapter.class = I2C_CLASS_HWMON;
@@ -749,7 +771,6 @@ static int __devinit tegra_i2c_probe(struct platform_device *pdev)
 	ret = i2c_add_numbered_adapter(&i2c_dev->adapter);
 	if (ret) {
 		dev_err(&pdev->dev, "Failed to add I2C adapter\n");
-		clk_disable_unprepare(i2c_dev->fast_clk);
 		return ret;
 	}
 
-- 
1.7.1.1

Re: [PATCH] i2c: tegra: dynamically control fast clk

[Stephen Warren]

On 08/17/2012 01:48 AM, Laxman Dewangan wrote:
> Tegra I2C driver enables the fast clock during initialization
> and does not disable till driver removed.
> Enable this clock before transfer and disable after transfer done.
> 
> Signed-off-by: Laxman Dewangan <ldewangan-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
> ---
> This patch is on top of the clock chnages which is in Tegra sub system and
> based on 
>  i2c: tegra: I2_M_NOSTART functionality not supported in Tegra20
> So recommend to go on tegra sub-system.

What exactly is this patch based on? I checked out Tegra's
for-3.7/drivers-i2c, cherry-picked the M_NOSTART patch you mentioned,
and attempted to apply this patch. It doesn't apply. Same if I don't
cherry-pick the M_NOSTART patch, and same for next-20120816 with/without
the M_NOSTART patch.

Re: [PATCH] i2c: tegra: dynamically control fast clk

[Laxman Dewangan]

On Saturday 18 August 2012 12:11 AM, Stephen Warren wrote:
> On 08/17/2012 01:48 AM, Laxman Dewangan wrote:
>> Tegra I2C driver enables the fast clock during initialization
>> and does not disable till driver removed.
>> Enable this clock before transfer and disable after transfer done.
>>
>> Signed-off-by: Laxman Dewangan<ldewangan-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
>> ---
>> This patch is on top of the clock chnages which is in Tegra sub system and
>> based on
>>   i2c: tegra: I2_M_NOSTART functionality not supported in Tegra20
>> So recommend to go on tegra sub-system.
> What exactly is this patch based on? I checked out Tegra's
> for-3.7/drivers-i2c, cherry-picked the M_NOSTART patch you mentioned,
> and attempted to apply this patch. It doesn't apply. Same if I don't
> cherry-pick the M_NOSTART patch, and same for next-20120816 with/without
> the M_NOSTART patch.

Then It seems I need to create the patch again and send it.  The 
M_NOSTART patch was on tot before clock related change and that is the 
reason it is not applying.
Should I re-send these two patches together as 1/2 and 2/2 to maintain 
sequence?
I can create based on your clock tree.

Re: [PATCH] i2c: tegra: dynamically control fast clk

[Stephen Warren]

On 08/17/2012 12:45 PM, Laxman Dewangan wrote:
> On Saturday 18 August 2012 12:11 AM, Stephen Warren wrote:
>> On 08/17/2012 01:48 AM, Laxman Dewangan wrote:
>>> Tegra I2C driver enables the fast clock during initialization
>>> and does not disable till driver removed.
>>> Enable this clock before transfer and disable after transfer done.
>>>
>>> Signed-off-by: Laxman Dewangan<ldewangan-DDmLM1+adcrQT0dZR+AlfA@public.gmane.org>
>>> ---
>>> This patch is on top of the clock chnages which is in Tegra sub
>>> system and
>>> based on
>>>   i2c: tegra: I2_M_NOSTART functionality not supported in Tegra20
>>> So recommend to go on tegra sub-system.
>> What exactly is this patch based on? I checked out Tegra's
>> for-3.7/drivers-i2c, cherry-picked the M_NOSTART patch you mentioned,
>> and attempted to apply this patch. It doesn't apply. Same if I don't
>> cherry-pick the M_NOSTART patch, and same for next-20120816 with/without
>> the M_NOSTART patch.
> 
> Then It seems I need to create the patch again and send it.  The
> M_NOSTART patch was on tot before clock related change and that is the
> reason it is not applying.
> Should I re-send these two patches together as 1/2 and 2/2 to maintain
> sequence?
> I can create based on your clock tree.

For any I2C-related changes I take through the Tegra tree, basing them
on top of for-3.7/drivers-i2c would be best. Feel free to send both
patches together again if that's easiest.