[RFC 2/3] ARM: Tegra: Device Tree Support: Add i2c devices

[grant.likely@secretlab.ca (Grant Likely)]

On Thu, May 12, 2011 at 6:34 AM, Stephen Warren <swarren@nvidia.com> wrote:
> John Bonesio wrote at Wednesday, May 11, 2011 5:27 PM:
>> This patch initializes i2c controller devices in board-dt.c. The i2c controller
>> is added to tegra250.dtsi so later on-board i2c devices can be found and
>> initialized based on the device tree information.
>>...
>> diff --git a/arch/arm/mach-tegra/board-dt.c b/arch/arm/mach-tegra/board-dt.c
>>...
>> +#include <linux/i2c.h>
>> +#include <linux/i2c-tegra.h>
>
> I don't think those headers are needed now the platform data isn't set up here.
>
>> diff --git a/drivers/i2c/busses/i2c-tegra.c b/drivers/i2c/busses/i2c-tegra.c
>>...
>> @@ -598,6 +609,7 @@ static int tegra_i2c_probe(struct platform_device *pdev)
>> ? ? ? i2c_dev->adapter.algo = &tegra_i2c_algo;
>> ? ? ? i2c_dev->adapter.dev.parent = &pdev->dev;
>> ? ? ? i2c_dev->adapter.nr = pdev->id;
>> + ? ? i2c_dev->adapter.dev.of_node = of_node_get(pdev->dev.of_node);
>
> It seems like users of this of_node (i.e. the probe function) could just
> access pdev->dev.of_node directly (since pdev is already passed in)
> rather than storing a copy here. At least, sdhci-tegra.c works that way.
> Still, this isn't a big deal, I think.

Actually, using of_node_get() here is the right thing since it
increases the reference count on the of_node.  However, the patch
should also do an of_node_put() in the remove hook, or in the .probe
error path.

>
>> @@ -605,6 +617,8 @@ static int tegra_i2c_probe(struct platform_device *pdev)
>> ? ? ? ? ? ? ? goto err_free_irq;
>> ? ? ? }
>>
>> + ? ? of_i2c_register_devices(&i2c_dev->adapter);
>> +
>
> I would have expected that to be performed inside the core I2C code,
> probably inside i2c_add_numbered_adapter? Still, it looks like the
> other I2C controllers don't already work that way, so this is probably
> more a suggestion for future cleanup than something to be addressed in
> this patch.

This may move into core code in the future, but for the moment the
drivers need to call it explicitly.

g.