RE: [PATCH V3 2/4] drivers/i2c/busses/i2c-at91.c: add new driver

Voss, Nikolaus
2011-11-09T16:01:55Z

Hi Ryan,

> > +#include <mach/at91_twi.h>
>
>
> This include file looks like it only contains register definitions which
> are used in this file. Would be good to either move them directly into
> this driver or move the header file to this directory and make it a
> local include.

Ok.

> > +
> > + dev->dev = get_device(&pdev->dev);
>
>
> Is this (and the put_device(&pdev->dev) in the exit code) necessary? I
> see that some other i2c drivers do this also, but I'm not familiar with
> using it in other device drivers. Isn't the reference count for
> pdev->dev already incremented by the fact we are probing the device?

It is incremented by the platform_device_register() which does a
device_add(). This seems to be enough, I removed the get-/put_device().

>
> > + dev->irq = irq->start;
> > + platform_set_drvdata(pdev, dev);
> > +
> > + dev->clk = clk_get(&pdev->dev, "twi_clk");
>
>
> This didn't get answered. Can't you just do:
>
> dev->clk = clk_get(&pdev->dev, NULL);
>
> and clkdev should figure out the correct clock based on the device pointer?

No, this doesn't work on at91 since the clocks have no dev_id property
but only con_id. I cannot see a reason for this, but that's the way it's
done. Multiple hardware interfaces are handled via a lookup table.

> > + rc = i2c_del_adapter(&dev->adapter);
>
>
> Most of the other i2c drivers don't check the return code for
> i2c_del_adapter. If this fails then you will unload the module, but
> potentially leak resources that i2c_del_adapter failed to free up. Not
> sure what the correct answer is here.

I don't really check the value but use it has exit code for the remove()-
function to indicate something went wrong. Just ignoring it wouldn't heal
the resource leakage.

Thanks for reviewing,

Niko