[U-Boot] Moving i2c_board_init to after i2c_init operations

[U-Boot] Moving i2c_board_init to after i2c_init operations

[Richard Retanubun]

Hi Heiko,

I am trying to do something similar to what you did in this commit:

http://git.denx.de/?p=u-boot/u-boot-i2c.git;a=commit;h=39df00d9aecfb465b9eec9af593f9b763fb5209a

and I have a question, must i2c_board_init for fsl_i2c.c be called before
the actual controller initialization? (i.e. setting the bus speed and the controller's slave address)

if we call it at the end of i2c_init, we can take advantage of the setups done before, no?

Most of the other implementation does it in the beginning because they can change the
i2c pins to GPIO and 'bit-bang' the reset pattern, and then change it back to i2c pins.

The alternative is of course to assume nothing in i2c_board_init, and configure everything
(I kinda liked to use set_i2c_bus_speed, rather than hardcoding something).

Since the kmeter1 board is the only user of i2c_board_init in fsl_i2c.c, would you be
opposed if I submit a patch that moves the call for i2c_board_init to the end of i2c_init?

Or, can I make another 'callpoint' (e.g. i2c_reset_bus) and call that at the end?

Thanks for your time.

- Richard Retanubun

[U-Boot] Moving i2c_board_init to after i2c_init operations

[Heiko Schocher]

Hello Richard,

Richard Retanubun wrote:
> I am trying to do something similar to what you did in this commit:
> 
> http://git.denx.de/?p=u-boot/u-boot-i2c.git;a=commit;h=39df00d9aecfb465b9eec9af593f9b763fb5209a
> 
> 
> and I have a question, must i2c_board_init for fsl_i2c.c be called before
> the actual controller initialization? (i.e. setting the bus speed and
> the controller's slave address)
> 
> if we call it at the end of i2c_init, we can take advantage of the
> setups done before, no?

Yes, you are right.

> Most of the other implementation does it in the beginning because they
> can change the
> i2c pins to GPIO and 'bit-bang' the reset pattern, and then change it
> back to i2c pins.

Yep.

> The alternative is of course to assume nothing in i2c_board_init, and
> configure everything
> (I kinda liked to use set_i2c_bus_speed, rather than hardcoding something).
> 
> Since the kmeter1 board is the only user of i2c_board_init in fsl_i2c.c,
> would you be
> opposed if I submit a patch that moves the call for i2c_board_init to
> the end of i2c_init?

No, this is OK, and looks cleaner to me. Thanks!

bye
Heiko
-- 
DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany

[U-Boot] [PATCH]fsl_i2c: Move i2c_board_init to after i2c_init operations

[richardretanubun at ruggedcom.com]

[U-Boot] [PATCH]fsl_i2c: Move i2c_board_init to after i2c_init operations

[Wolfgang Denk]

Dear richardretanubun at ruggedcom.com,

In message <20100412180215.GA11973@richardretanubun.eng.lan> you wrote:
> From 00f84e4a9a2d13971c9328fc815825456b25f760 Mon Sep 17 00:00:00 2001
> From: Richard Retanubun <richardretanubun@ruggedcom.com>
> Date: Mon, 12 Apr 2010 13:32:09 -0400
> Subject: [PATCH] fsl_i2c: Move the call for i2c_init_board to the end of i2c_init
> 
> This patch moved the call to i2c_init_board to the end of i2c_init.
> This allows the board fixup functions to take advantage of the
> setups done by i2c_init (i.e. bus speed and slave address).
> 
> On other boards, i2c_init_board is called before i2c_init operation
> because the method of resetting i2c bus typically uses GPIOs
> to bit-bang SCLK. For i2c controllers that is using fsl_i2c this is
> unneccessary because there is a i2c register access sequence that
> accomplish the same thing, and it is better to do the accesses
> after the bus speed and slave address have been configured.

I dislike such inconsitent behaviour. It would be better if we could
rely on a specific initialization sequence, i. e. the function always
be called at the beginning or always at the end. Having to deal with
a situation where one or the other might happen, even on the same
hardware, depending on if we use the HW or the SW I2C driver, sounds
like a nightmare to me.

If you need a late init function, then better add a new one.

Best regards,

Wolfgang Denk

-- 
DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
"Have you lived in this village all your life?"        "No, not yet."

[U-Boot] [PATCH]fsl_i2c: Move i2c_board_init to after i2c_init operations

[Richard Retanubun]

Wolfgang Denk wrote:
> 
> If you need a late init function, then better add a new one.

Hi Wolfgang,

That is one of the options I put forth, what would be a name you like for this callpoint?

i2c_board_late_init ??

- Richard

[U-Boot] [PATCH]fsl_i2c: Move i2c_board_init to after i2c_init operations

[Wolfgang Denk]

Dear Richard,

In message <4BC364D1.8020306@RuggedCom.com> you wrote:
> 
> That is one of the options I put forth, what would be a name you like for this callpoint?
> 
> i2c_board_late_init ??

I think we agree that it's not exactly an elegant name, but given the
fact that we already have board_late_init() it would be at least
consistent.

Best regards,

Wolfgang Denk

-- 
DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
Never underestimate the power of human stupidity  when  it  comes  to
using technology they don't understand.

[U-Boot] [PATCH]fsl_i2c: Add i2c_board_late_init

[richardretanubun at ruggedcom.com]

[U-Boot] [PATCH]fsl_i2c: Add i2c_board_late_init

[Wolfgang Denk]

Dear richardretanubun at ruggedcom.com,

In message <20100412191703.GA30835@richardretanubun.eng.lan> you wrote:
> From d0d9e0df99ce9035db43ebcf9d48601fa6f096d4 Mon Sep 17 00:00:00 2001
> From: Richard Retanubun <RichardRetanubun@RuggedCom.com>
> Date: Mon, 12 Apr 2010 15:08:17 -0400
> Subject: [PATCH] fsl_i2c: Added a callpoint for i2c_board_late_init
> 
> This patch adds a callpoint in i2c_init that allows board specific
> i2c board initialization (typically for i2c bus reset) that is called
> after i2c_init operations, allowing the i2c_board_late_init function
> to use the pre-configured i2c bus speed and slave address.
> ---
> 
> Hi Wolfgang & Heiko,
> 
> This is the patch that adds another callpoint. Thanks for
> all the feedback.
> 
> - Richard
> 
>  drivers/i2c/fsl_i2c.c |    8 ++++++++
>  1 files changed, 8 insertions(+), 0 deletions(-)
> 
> diff --git a/drivers/i2c/fsl_i2c.c b/drivers/i2c/fsl_i2c.c
> index 2241990..a1a62fa 100644
> --- a/drivers/i2c/fsl_i2c.c
> +++ b/drivers/i2c/fsl_i2c.c
> @@ -249,6 +249,14 @@ i2c_init(int speed, int slaveadd)
>  	writeb(0x0, &dev->sr);			/* clear status register */
>  	writeb(I2C_CR_MEN, &dev->cr);		/* start I2C controller */
>  #endif
> +
> +#ifdef CONFIG_SYS_I2C_BOARD_LATE_INIT
> +	/* Call board specific i2c bus reset routine after the bus has been   */
> +	/* initialized. Use either this callpoint or i2c_init_board; which is */
> +	/* called before i2c_init operations.                                 */
> +	/* For details about this problem see doc/I2C_Edge_Conditions.        */
> +	i2c_board_late_init();
> +#endif

Incorrect multiline comment style.

Instead of adding more #ifdef'ery we now tend to use weak symbols -
but I'm not sure about this here in this context, though. Heiko, what
do you think about this?

Best regards,

Wolfgang Denk

-- 
DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: wd at denx.de
There's an old proverb that says just about whatever you want it to.

[U-Boot] [PATCH]fsl_i2c: Add i2c_board_late_init

[Heiko Schocher]

Hello Wolfgang, Richard,

Wolfgang Denk wrote:
> Dear richardretanubun at ruggedcom.com,
> 
> In message <20100412191703.GA30835@richardretanubun.eng.lan> you wrote:
>> From d0d9e0df99ce9035db43ebcf9d48601fa6f096d4 Mon Sep 17 00:00:00 2001
>> From: Richard Retanubun <RichardRetanubun@RuggedCom.com>
>> Date: Mon, 12 Apr 2010 15:08:17 -0400
>> Subject: [PATCH] fsl_i2c: Added a callpoint for i2c_board_late_init
>>
>> This patch adds a callpoint in i2c_init that allows board specific
>> i2c board initialization (typically for i2c bus reset) that is called
>> after i2c_init operations, allowing the i2c_board_late_init function
>> to use the pre-configured i2c bus speed and slave address.
>> ---
>>
>> Hi Wolfgang & Heiko,
>>
>> This is the patch that adds another callpoint. Thanks for
>> all the feedback.
>>
>> - Richard
>>
>>  drivers/i2c/fsl_i2c.c |    8 ++++++++
>>  1 files changed, 8 insertions(+), 0 deletions(-)
>>
>> diff --git a/drivers/i2c/fsl_i2c.c b/drivers/i2c/fsl_i2c.c
>> index 2241990..a1a62fa 100644
>> --- a/drivers/i2c/fsl_i2c.c
>> +++ b/drivers/i2c/fsl_i2c.c
>> @@ -249,6 +249,14 @@ i2c_init(int speed, int slaveadd)
>>  	writeb(0x0, &dev->sr);			/* clear status register */
>>  	writeb(I2C_CR_MEN, &dev->cr);		/* start I2C controller */
>>  #endif
>> +
>> +#ifdef CONFIG_SYS_I2C_BOARD_LATE_INIT
>> +	/* Call board specific i2c bus reset routine after the bus has been   */
>> +	/* initialized. Use either this callpoint or i2c_init_board; which is */
>> +	/* called before i2c_init operations.                                 */
>> +	/* For details about this problem see doc/I2C_Edge_Conditions.        */
>> +	i2c_board_late_init();
>> +#endif
> 
> Incorrect multiline comment style.

Yep, Richard please fix this. Also it would be nice to have an
entry in the README for your new callpoint.

> Instead of adding more #ifdef'ery we now tend to use weak symbols -
> but I'm not sure about this here in this context, though. Heiko, what
> do you think about this?

I would prefer here the define version, but common uboot style
is, as you said, using weak symbols ... If using here weak symbols,
I vote for changing the "#ifdef CONFIG_SYS_I2C_INIT_BOARD" case
also to weak.

Thanks.

bye
Heiko
-- 
DENX Software Engineering GmbH,     MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany

[U-Boot] [PATCH v3]fsl_i2c: Add i2c_board_late_init

[richardretanubun at ruggedcom.com]

[U-Boot] [PATCH v2]fsl_i2c: Add i2c_board_late_init

[richardretanubun at ruggedcom.com]