On 09/18/2012 07:15 PM, Bo Shen wrote:

Hi Stephen Warren,

On 9/18/2012 22:51, Stephen Warren wrote:

quoted

On 09/18/2012 03:02 AM, Bo Shen wrote:

quoted

When i2c-gpio node number is greater than 1, the second can not
sucessfully
regiter

Using alias method to get the pdev->id, or else the second device
will use
the same id which will cause fail to register

pdev->id shouldn't be used at all with device tree. Why does
registration fail without this change?

I add the debug info, and it give the following error without this patch.

--<8----------------------------------
adap->name = i2c-gpio-1
i2c-gpio i2c.2: using pins 30 (SDA) and 31 (SCL)
adap->name = i2c-gpio-1
i2c-gpio: probe of i2c.3 failed with error -16
-->8----------------------------------

With this patch, it successfully registered.
--<8----------------------------------
adap->name = i2c-gpio0
i2c-gpio i2c.2: using pins 30 (SDA) and 31 (SCL)
adap->name = i2c-gpio1
i2c-gpio i2c.3: using pins 90 (SDA) and 91 (SCL)
-->8----------------------------------

Yes, that explains why the registration fails, but not why this patch is
the correct solution to the problem.

The problematic code appears to be:

snprintf(adap->name, sizeof(adap->name), "i2c-gpio%d", pdev->id);

Instead, I think that should be something more like:

adap->name = dev_name(&pdev->dev);

or perhaps:

if (pdev->dev.of_node)
  /* named will be based on DT node name */
  adap->name = dev_name(&pdev->dev);
else
  snprintf(adap->name, sizeof(adap->name), "i2c-gpio%d", pdev->id);

?