[lm-sensors] lm75 on a ppc405

[lm-sensors] lm75 on a ppc405

[Martin Hicks]

hi,

I've got a board with an lm75 connected to the iic of a ppc405.
Inserting the i2c-ibm_iic and lm75 (and dependent) modules doesn't find
the device.  I poked around a bit and applying the following patch
seemed to make things better (against 2.6.11.x):

Index: kernel/drivers/i2c/chips/lm75.c
=================================RCS file: /opt/targa/src/e-dtu/kernel/drivers/i2c/chips/lm75.c,v
retrieving revision 1.1.1.1
diff -u -p -r1.1.1.1 lm75.c
--- kernel/drivers/i2c/chips/lm75.c	13 May 2005 17:59:52 -0000	1.1.1.1
+++ kernel/drivers/i2c/chips/lm75.c	7 Dec 2005 20:28:13 -0000
@@ -104,8 +104,6 @@ static DEVICE_ATTR(temp1_input, S_IRUGO,
 
 static int lm75_attach_adapter(struct i2c_adapter *adapter)
 {
-	if (!(adapter->class & I2C_CLASS_HWMON))
-		return 0;
 	return i2c_detect(adapter, &addr_data, lm75_detect);
 }


This may be wrong, but why do we care if the *adapter* (i.e., the ppc's
iic) is a HWMON device?  We want the i2c adapters to scan their busses
for lm75 devices.

Any insight or is this a correct patch?  With this patch I see the lm75
at 0x48 and the temperature it reports is reasonable.

mh

-- 
Martin Hicks || mort at bork.org || PGP/GnuPG: 0x4C7F2BEE

[lm-sensors] lm75 on a ppc405

[Jean Delvare]

Hi Martin,

> I've got a board with an lm75 connected to the iic of a ppc405.
> Inserting the  and lm75 (and dependent) modules doesn't find
> the device.  I poked around a bit and applying the following patch
> seemed to make things better (against 2.6.11.x):
> 
> Index: kernel/drivers/i2c/chips/lm75.c
> =================================> RCS file: /opt/targa/src/e-dtu/kernel/drivers/i2c/chips/lm75.c,v
> retrieving revision 1.1.1.1
> diff -u -p -r1.1.1.1 lm75.c
> --- kernel/drivers/i2c/chips/lm75.c	13 May 2005 17:59:52 -0000	1.1.1.1
> +++ kernel/drivers/i2c/chips/lm75.c	7 Dec 2005 20:28:13 -0000
> @@ -104,8 +104,6 @@ static DEVICE_ATTR(temp1_input, S_IRUGO,
>  
>  static int lm75_attach_adapter(struct i2c_adapter *adapter)
>  {
> -	if (!(adapter->class & I2C_CLASS_HWMON))
> -		return 0;
>  	return i2c_detect(adapter, &addr_data, lm75_detect);
>  }
> 
> 
> This may be wrong, but why do we care if the *adapter* (i.e., the ppc's
> iic) is a HWMON device?  We want the i2c adapters to scan their busses
> for lm75 devices.

We care in that some adapters do not want to be probed for random
chips, for they know exactly which chips they can have. This is
frequently the case for media/video devices. The class separation was
introduced to prevent useless probing which was said to sometimes
confuse chips and busses. We might move to a better approach in the
future, but for now we'll just stick to this one as it works rather
fine.

> Any insight or is this a correct patch?  With this patch I see the lm75
> at 0x48 and the temperature it reports is reasonable.

The correct approach is to add I2C_CLASS_HWMON to i2c-ibm_iic's class
flags. I'd take a patch doing that.

-- 
Jean Delvare

[lm-sensors] lm75 on a ppc405

[Martin Hicks]

On Wed, Dec 07, 2005 at 11:14:23PM +0100, Jean Delvare wrote:
> 

[snip]

> We care in that some adapters do not want to be probed for random
> chips, for they know exactly which chips they can have. This is
> frequently the case for media/video devices. The class separation was
> introduced to prevent useless probing which was said to sometimes
> confuse chips and busses. We might move to a better approach in the
> future, but for now we'll just stick to this one as it works rather
> fine.
> 

Ah, that explains it pefectly.

> > Any insight or is this a correct patch?  With this patch I see the lm75
> > at 0x48 and the temperature it reports is reasonable.
> 
> The correct approach is to add I2C_CLASS_HWMON to i2c-ibm_iic's class
> flags. I'd take a patch doing that.

Excellent.  Tested against 2.6.11.9, and compile tested with Linus'
latest git tree.

Thanks
mh

-- 
Martin Hicks || mort at bork.org || PGP/GnuPG: 0x4C7F2BEE


[PATCH] i2c/ibm_iic - Add to HWMON class

Add the ibm_iic driver to the HWMON class so it will scan the
bus for connected hardware monitor sensors.

Signed-off-by:  Martin Hicks <mort at bork.org>

---

 drivers/i2c/busses/i2c-ibm_iic.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)

applies-to: 75f680b437862b125cbce00709fcebf57f146b88
72522808f521cb378a1ed6ee490a9ea7c6e977f7
diff --git a/drivers/i2c/busses/i2c-ibm_iic.c b/drivers/i2c/busses/i2c-ibm_iic.c
index 1a58725..87fae93 100644
--- a/drivers/i2c/busses/i2c-ibm_iic.c
+++ b/drivers/i2c/busses/i2c-ibm_iic.c
@@ -725,6 +725,7 @@ static int __devinit iic_probe(struct oc
 	strcpy(adap->name, "IBM IIC");
 	i2c_set_adapdata(adap, dev);
 	adap->id = I2C_HW_OCP;
+	adap->class = I2C_CLASS_HWMON;
 	adap->algo = &iic_algo;
 	adap->client_register = NULL;
 	adap->client_unregister = NULL;

[lm-sensors] lm75 on a ppc405

[Jean Delvare]

Hi Martin,

> > The correct approach is to add I2C_CLASS_HWMON to i2c-ibm_iic's class
> > flags. I'd take a patch doing that.
> 
> Excellent.  Tested against 2.6.11.9, and compile tested with Linus'
> latest git tree.

Applied, thanks.

-- 
Jean Delvare