diff mbox series

[07/19] media: i2c: ds90ub953: Speed-up I2C watchdog timer

Message ID 20250110-ub9xx-improvements-v1-7-e0b9a1f644da@ideasonboard.com
State Superseded
Headers show
Series media: i2c: ds90ub9xx: Error handling, UB9702 improvements | expand

Commit Message

Tomi Valkeinen Jan. 10, 2025, 9:14 a.m. UTC 
From: Jai Luthra <jai.luthra@ideasonboard.com>

On the I2C bus for remote clients (sensors), by default the watchdog
timer expires in 1s. To allow for a quicker system bring-up time, TI
recommends to speed it up to 50us [1].

[1]: Section 7.3.1.1 - https://www.ti.com/lit/gpn/ds90ub953-q1

Signed-off-by: Jai Luthra <jai.luthra@ideasonboard.com>
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
---
 drivers/media/i2c/ds90ub953.c | 11 +++++++++++
 1 file changed, 11 insertions(+)

Comments

Tomi Valkeinen Jan. 24, 2025, 1:19 p.m. UTC | #1 
Hi,

On 15/01/2025 16:17, Sakari Ailus wrote:
> Moi,
> 
> On Fri, Jan 10, 2025 at 11:14:07AM +0200, Tomi Valkeinen wrote:
>> From: Jai Luthra <jai.luthra@ideasonboard.com>
>>
>> On the I2C bus for remote clients (sensors), by default the watchdog
>> timer expires in 1s. To allow for a quicker system bring-up time, TI
>> recommends to speed it up to 50us [1].
>>
>> [1]: Section 7.3.1.1 - https://www.ti.com/lit/gpn/ds90ub953-q1
>>
>> Signed-off-by: Jai Luthra <jai.luthra@ideasonboard.com>
>> Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
>> ---
>>   drivers/media/i2c/ds90ub953.c | 11 +++++++++++
>>   1 file changed, 11 insertions(+)
>>
>> diff --git a/drivers/media/i2c/ds90ub953.c b/drivers/media/i2c/ds90ub953.c
>> index 99a4852b9381..6c36980e8beb 100644
>> --- a/drivers/media/i2c/ds90ub953.c
>> +++ b/drivers/media/i2c/ds90ub953.c
>> @@ -54,6 +54,10 @@
>>   #define UB953_REG_CLKOUT_CTRL0			0x06
>>   #define UB953_REG_CLKOUT_CTRL1			0x07
>>   
>> +#define UB953_REG_I2C_CONTROL2			0x0a
>> +#define UB953_REG_I2C_CONTROL2_SDA_OUTPUT_SETUP_SHIFT	4
>> +#define UB953_REG_I2C_CONTROL2_BUS_SPEEDUP	BIT(1)
>> +
>>   #define UB953_REG_SCL_HIGH_TIME			0x0b
>>   #define UB953_REG_SCL_LOW_TIME			0x0c
>>   
>> @@ -1320,6 +1324,13 @@ static int ub953_hw_init(struct ub953_data *priv)
>>   	if (ret)
>>   		return ret;
>>   
>> +	v = 0;
>> +	v |= 1 << UB953_REG_I2C_CONTROL2_SDA_OUTPUT_SETUP_SHIFT;
> 
> BIT()? Or at least 1U <<< ...;.

It's a three-bit field, the value just happens to be 1. What's wrong 
with 1 << SHIFT?

> 
>> +	v |= UB953_REG_I2C_CONTROL2_BUS_SPEEDUP;
>> +	ret = ub953_write(priv, UB953_REG_I2C_CONTROL2, v, NULL);
> 
> I'd just do this without a temporary variable. If you prefer to keep it, do
> assign the first calculated value there first and remove the assignment to
> zero.

I think we can do without.

>> +	if (ret)
>> +		return ret;
> 
> No need for this.

No, but it keeps the code structure consistent and allows easy 
future/debug modifications.

  Tomi
Sakari Ailus Feb. 3, 2025, 9:23 a.m. UTC | #2 
Moi,

On Fri, Jan 24, 2025 at 03:19:32PM +0200, Tomi Valkeinen wrote:
> Hi,
> 
> On 15/01/2025 16:17, Sakari Ailus wrote:
> > Moi,
> > 
> > On Fri, Jan 10, 2025 at 11:14:07AM +0200, Tomi Valkeinen wrote:
> > > From: Jai Luthra <jai.luthra@ideasonboard.com>
> > > 
> > > On the I2C bus for remote clients (sensors), by default the watchdog
> > > timer expires in 1s. To allow for a quicker system bring-up time, TI
> > > recommends to speed it up to 50us [1].
> > > 
> > > [1]: Section 7.3.1.1 - https://www.ti.com/lit/gpn/ds90ub953-q1
> > > 
> > > Signed-off-by: Jai Luthra <jai.luthra@ideasonboard.com>
> > > Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ideasonboard.com>
> > > ---
> > >   drivers/media/i2c/ds90ub953.c | 11 +++++++++++
> > >   1 file changed, 11 insertions(+)
> > > 
> > > diff --git a/drivers/media/i2c/ds90ub953.c b/drivers/media/i2c/ds90ub953.c
> > > index 99a4852b9381..6c36980e8beb 100644
> > > --- a/drivers/media/i2c/ds90ub953.c
> > > +++ b/drivers/media/i2c/ds90ub953.c
> > > @@ -54,6 +54,10 @@
> > >   #define UB953_REG_CLKOUT_CTRL0			0x06
> > >   #define UB953_REG_CLKOUT_CTRL1			0x07
> > > +#define UB953_REG_I2C_CONTROL2			0x0a
> > > +#define UB953_REG_I2C_CONTROL2_SDA_OUTPUT_SETUP_SHIFT	4
> > > +#define UB953_REG_I2C_CONTROL2_BUS_SPEEDUP	BIT(1)
> > > +
> > >   #define UB953_REG_SCL_HIGH_TIME			0x0b
> > >   #define UB953_REG_SCL_LOW_TIME			0x0c
> > > @@ -1320,6 +1324,13 @@ static int ub953_hw_init(struct ub953_data *priv)
> > >   	if (ret)
> > >   		return ret;
> > > +	v = 0;
> > > +	v |= 1 << UB953_REG_I2C_CONTROL2_SDA_OUTPUT_SETUP_SHIFT;
> > 
> > BIT()? Or at least 1U <<< ...;.
> 
> It's a three-bit field, the value just happens to be 1. What's wrong with 1
> << SHIFT?

Shifting a signed value leads to the sign bit being undefined on some
architectures.

> 
> > 
> > > +	v |= UB953_REG_I2C_CONTROL2_BUS_SPEEDUP;
> > > +	ret = ub953_write(priv, UB953_REG_I2C_CONTROL2, v, NULL);
> > 
> > I'd just do this without a temporary variable. If you prefer to keep it, do
> > assign the first calculated value there first and remove the assignment to
> > zero.
> 
> I think we can do without.
> 
> > > +	if (ret)
> > > +		return ret;
> > 
> > No need for this.
> 
> No, but it keeps the code structure consistent and allows easy future/debug
> modifications.

Please still remove such redundancies.
diff mbox series

Patch

diff --git a/drivers/media/i2c/ds90ub953.c b/drivers/media/i2c/ds90ub953.c
index 99a4852b9381..6c36980e8beb 100644
--- a/drivers/media/i2c/ds90ub953.c
+++ b/drivers/media/i2c/ds90ub953.c
@@ -54,6 +54,10 @@ 
 #define UB953_REG_CLKOUT_CTRL0			0x06
 #define UB953_REG_CLKOUT_CTRL1			0x07
 
+#define UB953_REG_I2C_CONTROL2			0x0a
+#define UB953_REG_I2C_CONTROL2_SDA_OUTPUT_SETUP_SHIFT	4
+#define UB953_REG_I2C_CONTROL2_BUS_SPEEDUP	BIT(1)
+
 #define UB953_REG_SCL_HIGH_TIME			0x0b
 #define UB953_REG_SCL_LOW_TIME			0x0c
 
@@ -1320,6 +1324,13 @@  static int ub953_hw_init(struct ub953_data *priv)
 	if (ret)
 		return ret;
 
+	v = 0;
+	v |= 1 << UB953_REG_I2C_CONTROL2_SDA_OUTPUT_SETUP_SHIFT;
+	v |= UB953_REG_I2C_CONTROL2_BUS_SPEEDUP;
+	ret = ub953_write(priv, UB953_REG_I2C_CONTROL2, v, NULL);
+	if (ret)
+		return ret;
+
 	return 0;
 }