[U-Boot] Supporting SCCB protocol

[U-Boot] Supporting SCCB protocol

[John Tobias]

Hi All,

I would like to know if someone here have implemented a SCCB support in
uboot?. I would appreciate if you could give me some snapshot of your
codes?.

Regards,

John

[U-Boot] Supporting SCCB protocol

[Detlev Zundel]

Hi John,

> I would like to know if someone here have implemented a SCCB support in
> uboot?. I would appreciate if you could give me some snapshot of your
> codes?.

It would be good to give some context for people not dealing with the
specific topic on a daily basis.

A quick web search for sccb finds "South Carolina Commission for the
Blind" - I guess you don't mean that :)

Apart form that, what would you expect from such a support in a
boot-loader?

Cheers
  Detlev

-- 
I think that level of generalization is too abstract for useful thinking.
             -- Richard Stallman in <E19N344-0006Q9-Bt@fencepost.gnu.org>
--
DENX Software Engineering GmbH,      MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich,  Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-40 Fax: (+49)-8142-66989-80 Email: dzu at denx.de

[U-Boot] Supporting SCCB protocol

[John Tobias]

That's correct! I should elaborate it. It should be (Serial Camera Control
Bus) protocol developed by omnivision.
I am using a OV2715 sensor and I need to access the registers of the said
sensor, I have to modify the I2C read/write in uboot to support the SCCB
transactions.

Here's my question:
If my sensor has power and a clock, does it response to the I2C probe or I
have to modify it too?. Right now, If I run iprobe, it did not detect my
sensor and not sure what it caused.

Regards,

john



On Mon, Jun 6, 2011 at 4:15 AM, Detlev Zundel <dzu@denx.de> wrote:

> Hi John,
>
> > I would like to know if someone here have implemented a SCCB support in
> > uboot?. I would appreciate if you could give me some snapshot of your
> > codes?.
>
> It would be good to give some context for people not dealing with the
> specific topic on a daily basis.
>
> A quick web search for sccb finds "South Carolina Commission for the
> Blind" - I guess you don't mean that :)
>
> Apart form that, what would you expect from such a support in a
> boot-loader?
>
> Cheers
>  Detlev
>
> --
> I think that level of generalization is too abstract for useful thinking.
>             -- Richard Stallman in <E19N344-0006Q9-Bt@fencepost.gnu.org>
> --
> DENX Software Engineering GmbH,      MD: Wolfgang Denk & Detlev Zundel
> HRB 165235 Munich,  Office: Kirchenstr.5, D-82194 Groebenzell, Germany
> Phone: (+49)-8142-66989-40 Fax: (+49)-8142-66989-80 Email: dzu at denx.de
>

[U-Boot] Supporting SCCB protocol

[Wolfgang Denk]

Dear John Tobias,

In message <BANLkTimzdPONQ5vQuLUVNQNURF85VtiC5Q@mail.gmail.com> you wrote:
>
> That's correct! I should elaborate it. It should be (Serial Camera Control
> Bus) protocol developed by omnivision.
> I am using a OV2715 sensor and I need to access the registers of the said
> sensor, I have to modify the I2C read/write in uboot to support the SCCB
> transactions.

Which exact operations do you need to perform in U-Boot?

I would expect that initializing a camera controller (which is
probably not used in any parts of U-Boot code) should rathe rbe done
in the OS device driver.

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
Murder is contrary to the laws of man and God.
	-- M-5 Computer, "The Ultimate Computer", stardate 4731.3

[U-Boot] Supporting SCCB protocol

[John Tobias]

Hi Wolfgang Denk,

The actual initialisation of the sensor is in the OS. But, I need an early
access to get/set the information in the OTP registers of the sensor.

Regards,

john

On Mon, Jun 6, 2011 at 1:11 PM, Wolfgang Denk <wd@denx.de> wrote:

> Dear John Tobias,
>
> In message <BANLkTimzdPONQ5vQuLUVNQNURF85VtiC5Q@mail.gmail.com> you wrote:
> >
> > That's correct! I should elaborate it. It should be (Serial Camera
> Control
> > Bus) protocol developed by omnivision.
> > I am using a OV2715 sensor and I need to access the registers of the said
> > sensor, I have to modify the I2C read/write in uboot to support the SCCB
> > transactions.
>
> Which exact operations do you need to perform in U-Boot?
>
> I would expect that initializing a camera controller (which is
> probably not used in any parts of U-Boot code) should rathe rbe done
> in the OS device driver.
>
> 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
> Murder is contrary to the laws of man and God.
>        -- M-5 Computer, "The Ultimate Computer", stardate 4731.3
>

[U-Boot] Supporting SCCB protocol

[Wolfgang Denk]

Dear John Tobias,

In message <BANLkTin9pfUZ5krZUoxDDbbsJHr4uY3boQ@mail.gmail.com> you wrote:
>
> The actual initialisation of the sensor is in the OS. But, I need an early
> access to get/set the information in the OTP registers of the sensor.

Could you please explain why this cannot be done in the OS driver
initialization code as well?

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
Do not underestimate the value of print statements for debugging.

[U-Boot] Supporting SCCB protocol

[John Tobias]

I am going to use the OTP register to put a unique ID of the board. In order
to do that, I don't have to boot the OS if I need to read/write the unique
ID of the board.

Regards,

john

On Mon, Jun 6, 2011 at 2:12 PM, Wolfgang Denk <wd@denx.de> wrote:

> Dear John Tobias,
>
> In message <BANLkTin9pfUZ5krZUoxDDbbsJHr4uY3boQ@mail.gmail.com> you wrote:
> >
> > The actual initialisation of the sensor is in the OS. But, I need an
> early
> > access to get/set the information in the OTP registers of the sensor.
>
> Could you please explain why this cannot be done in the OS driver
> initialization code as well?
>
> 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
> Do not underestimate the value of print statements for debugging.
>

[U-Boot] Supporting SCCB protocol

[Wolfgang Denk]

Dear John Tobias,

In message <BANLkTinn5oA711EuOELQeNRk2uYQ1N4+nw@mail.gmail.com> you wrote:
> 
> I am going to use the OTP register to put a unique ID of the board. In order
> to do that, I don't have to boot the OS if I need to read/write the unique
> ID of the board.
...
> On Mon, Jun 6, 2011 at 2:12 PM, Wolfgang Denk <wd@denx.de> wrote:
...
> > Could you please explain why this cannot be done in the OS driver
> > initialization code as well?

Well, this is obviously nowhere needed for U-Boot operation, and you
also don't need this in U-Boot to boot your OS.

See bullet # 2 at
http://www.denx.de/wiki/view/U-Boot/DesignPrinciples#2_Keep_it_Fast :
We don't initialize things in U-Boot, that are not needed here, unless
there is a very good reason for it.

In your case, such initialization should be done in the OS device
driver.  Leave it out of U-Boot.

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
Lots of folks confuse bad management with destiny.   -- Frank Hubbard

[U-Boot] Supporting SCCB protocol

[John Tobias]

Thanks for chatting.

Regards,

john

On Mon, Jun 6, 2011 at 3:26 PM, Wolfgang Denk <wd@denx.de> wrote:

> Dear John Tobias,
>
> In message <BANLkTinn5oA711EuOELQeNRk2uYQ1N4+nw@mail.gmail.com> you wrote:
> >
> > I am going to use the OTP register to put a unique ID of the board. In
> order
> > to do that, I don't have to boot the OS if I need to read/write the
> unique
> > ID of the board.
> ...
> > On Mon, Jun 6, 2011 at 2:12 PM, Wolfgang Denk <wd@denx.de> wrote:
> ...
> > > Could you please explain why this cannot be done in the OS driver
> > > initialization code as well?
>
> Well, this is obviously nowhere needed for U-Boot operation, and you
> also don't need this in U-Boot to boot your OS.
>
> See bullet # 2 at
> http://www.denx.de/wiki/view/U-Boot/DesignPrinciples#2_Keep_it_Fast :
> We don't initialize things in U-Boot, that are not needed here, unless
> there is a very good reason for it.
>
> In your case, such initialization should be done in the OS device
> driver.  Leave it out of U-Boot.
>
> 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
> Lots of folks confuse bad management with destiny.   -- Frank Hubbard
>

[U-Boot] Supporting SCCB protocol

[Mike Frysinger]

On Monday, June 06, 2011 16:48:05 John Tobias wrote:

please dont top post in your replies
-mike
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[U-Boot] Supporting SCCB protocol

[Detlev Zundel]

Hi John,

> That's correct! I should elaborate it. It should be (Serial Camera Control
> Bus) protocol developed by omnivision.
> I am using a OV2715 sensor and I need to access the registers of the said
> sensor, I have to modify the I2C read/write in uboot to support the SCCB
> transactions.

So SCCB is really only another name for I2C or are there differences in
the protocol?

If the first holds, then the infrastructure is already thereand you
should be able to use the i2c commands.  If the latter then you really
shoudl come up with your own "sccb" driver.  Probably basing it on
drivers.i2c/soft_i2c.c would be a good idea.

> Here's my question:
> If my sensor has power and a clock, does it response to the I2C probe or I
> have to modify it too?. Right now, If I run iprobe, it did not detect my
> sensor and not sure what it caused.

This should be discoverable by reading the manuals of the sensor.  If
this is at all like I2C, then it should definitely answer when its clock
and data pins are driven by I2C.  Did you check with an oscilloscope
that you really are talking to the chip?

Cheers
  Detlev

-- 
-- Question authority!
-- Yeah, says who?
--
DENX Software Engineering GmbH,      MD: Wolfgang Denk & Detlev Zundel
HRB 165235 Munich,  Office: Kirchenstr.5, D-82194 Groebenzell, Germany
Phone: (+49)-8142-66989-40 Fax: (+49)-8142-66989-80 Email: dzu at denx.de

[U-Boot] Supporting SCCB protocol

[Mike Frysinger]

On Wednesday, June 08, 2011 03:54:01 Detlev Zundel wrote:
> > That's correct! I should elaborate it. It should be (Serial Camera
> > Control Bus) protocol developed by omnivision.
> > I am using a OV2715 sensor and I need to access the registers of the said
> > sensor, I have to modify the I2C read/write in uboot to support the SCCB
> > transactions.
> 
> So SCCB is really only another name for I2C or are there differences in
> the protocol?

there are slight differences.  enough that existing i2c signals arent 
sufficient, but not enough that tweaking existing i2c framework shouldnt be 
too much of a hassle to make work.
-mike
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