i2c-imx: Autoprobe of eeproms

i2c-imx: Autoprobe of eeproms

[Mattias Walstrom]

I have tried to get autoprobe of eeproms to work on a custom freescale
mx27-board, and i found out that the i2c-imx driver was missing the
following, is there a reason for this, most other i2c-bus drivers seems
to have it?

--- linux-2.6.32.8.orig/drivers/i2c/busses/i2c-imx.c    2010-02-09
13:57:19.000000000 +0100
+++ linux-2.6.32.8/drivers/i2c/busses/i2c-imx.c 2010-02-12
11:30:12.000000000 +0100
@@ -521,6 +521,7 @@
        i2c_imx->adapter.algo           = &i2c_imx_algo;
        i2c_imx->adapter.dev.parent     = &pdev->dev;
        i2c_imx->adapter.nr             = pdev->id;
+        i2c_imx->adapter.class          = I2C_CLASS_HWMON | I2C_CLASS_SPD;
        i2c_imx->irq                    = irq;
        i2c_imx->base                   = base;
        i2c_imx->res                    = res;


Best regards
Mattias Walstr?m

i2c-imx: Autoprobe of eeproms

[Wolfram Sang]

Hi Mattias,

On Fri, Feb 12, 2010 at 11:15:51PM +0100, Mattias Walstrom wrote:

> I have tried to get autoprobe of eeproms to work on a custom freescale
> mx27-board, and i found out that the i2c-imx driver was missing the
> following, is there a reason for this, most other i2c-bus drivers seems
> to have it?

Yes. Autoprobing on I2C is not favoured (can have side-effects) with embedded
platforms, so the proper way is to declare the eeprom as board-info or
instantiate it at runtime.

Check Documentation/i2c/instantiating-devices for further info.

Regards,

   Wolfram

-- 
Pengutronix e.K.                           | Wolfram Sang                |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |
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i2c-imx: Autoprobe of eeproms

[Uwe Kleine-König]

On Fri, Feb 12, 2010 at 11:15:51PM +0100, Mattias Walstrom wrote:
> I have tried to get autoprobe of eeproms to work on a custom freescale
> mx27-board, and i found out that the i2c-imx driver was missing the
> following, is there a reason for this, most other i2c-bus drivers seems
> to have it?
> 
> --- linux-2.6.32.8.orig/drivers/i2c/busses/i2c-imx.c    2010-02-09
> 13:57:19.000000000 +0100
> +++ linux-2.6.32.8/drivers/i2c/busses/i2c-imx.c 2010-02-12
> 11:30:12.000000000 +0100
> @@ -521,6 +521,7 @@
>         i2c_imx->adapter.algo           = &i2c_imx_algo;
>         i2c_imx->adapter.dev.parent     = &pdev->dev;
>         i2c_imx->adapter.nr             = pdev->id;
> +        i2c_imx->adapter.class          = I2C_CLASS_HWMON | I2C_CLASS_SPD;
>         i2c_imx->irq                    = irq;
>         i2c_imx->base                   = base;
>         i2c_imx->res                    = res;
Your patch is broken.  drivers/i2c/busses/i2c-imx.c uses tabs for
indention, not spaces.

(Note, this doesn't mean I'd ack your patch, see Wolfram's reply.)

Best regards
Uwe

-- 
Pengutronix e.K.                           | Uwe Kleine-K?nig            |
Industrial Linux Solutions                 | http://www.pengutronix.de/  |

i2c-imx: Autoprobe of eeproms

[Ben Dooks]

On Fri, Feb 12, 2010 at 11:15:51PM +0100, Mattias Walstrom wrote:
> I have tried to get autoprobe of eeproms to work on a custom freescale
> mx27-board, and i found out that the i2c-imx driver was missing the
> following, is there a reason for this, most other i2c-bus drivers seems
> to have it?

auto-probing of anything on an i2c bus is always going to be trumped
by actually knowing. The limited address space means often different
types of peripherals can end up with similar addresses.

It is highly recommended in the ARM world where the board information is
known from early in the initialisation process that the board registers
the devices it knows to have available so that the i2c core can atatch
the relevant drivers.

I'm not even sure if SPD is the right class to have on this, I think
Jean Delvare has pronounced on this on the linux-i2c list (iirc, it
is for probing DRAM DIMMS).

Even if Jean hasn't nixed this, I would still prefer not to apply this.

PS, this should have been cc'd to the linux-i2c list!
 
> --- linux-2.6.32.8.orig/drivers/i2c/busses/i2c-imx.c    2010-02-09
> 13:57:19.000000000 +0100
> +++ linux-2.6.32.8/drivers/i2c/busses/i2c-imx.c 2010-02-12
> 11:30:12.000000000 +0100
> @@ -521,6 +521,7 @@
>         i2c_imx->adapter.algo           = &i2c_imx_algo;
>         i2c_imx->adapter.dev.parent     = &pdev->dev;
>         i2c_imx->adapter.nr             = pdev->id;
> +        i2c_imx->adapter.class          = I2C_CLASS_HWMON | I2C_CLASS_SPD;
>         i2c_imx->irq                    = irq;
>         i2c_imx->base                   = base;
>         i2c_imx->res                    = res;
> 
> 
> Best regards
> Mattias Walstr?m

-- 
Ben

Q:      What's a light-year?
A:      One-third less calories than a regular year.