Re: [PATCH v2 i2c-master] i2c: microchip: pci1xxxx: Add driver for I2C host controller in multifunction endpoint of pci1xxxx switch

[Andy Shevchenko]

On Fri, Sep 02, 2022 at 11:31:11AM +0000, Tharunkumar.Pasumarthi@xxxxxxxxxxxxx wrote:
> On Thu, 2022-09-01 at 21:47 +0300, Andy Shevchenko wrote:

...

> > > +             if (buf)
> > > +                     memcpy_toio((i2c->i2c_base + SMBUS_MST_BUF), buf,
> > > transferlen);
> > 
> > Why do you need buf checks? Is your code can shoot itself in the foot?
> 
> Yes, buf will be passed as NULL in some cases. So, this check is required.

Can you show an excerpt of the caller which passes NULL?

...

> > Each long sleep (20 ms is quite long) has to be explained. But this entire
> > loop
> > looks like a band-aid of lack of IRQ or so. Why do you need to poll?
> 
> This handling takes care of special case when system is put to suspend when i2c
> transfer is progress in driver. We will wait until transfer completes.

This should be at least a comment in the code.

...

> > > +     pci1xxxx_i2c_init(i2c);
> > 
> > Here you need to wrap pci1xxxx_i2c_shutdown() to be devm_. See below.
> > 
> > > +     ret = pci_alloc_irq_vectors(pdev, 1, 1, PCI_IRQ_ALL_TYPES);
> > > +     if (ret < 0) {
> > > +             pci1xxxx_i2c_shutdown(i2c);
> 
> I am not getting. Are you suggesting to change API name to
> devm_pci1xxxx_i2c_shutdown?
> 
> > > +
> > > +     ret = devm_i2c_add_adapter(&pdev->dev, &i2c->adap);
> > > +     if (ret) {
> > > +             dev_err(&pdev->dev, "i2c add adapter failed = %d\n", ret);
> > 
> > > +             pci1xxxx_i2c_shutdown(i2c);
> > 
> > You can't mix devm_ and non-devm_ in such manner. It's asking for troubles at
> > ->remove() or unbind stages.
> 
> I am not getting this comment. Can you kindly explain more.
> 
> > > +             return ret;

Explanations [1] & [2]. Example how to workaround [3].

[1]: https://www.mail-archive.com/linux-kernel@xxxxxxxxxxxxxxx/msg1949091.html
[2]: https://lore.kernel.org/all/YXktrG1LhK5tj2uF@xxxxxxxxxxxxxxxxxx/
[3]: https://www.spinics.net/lists/kernel/msg4433985.html

...

> > After fixing above, convert the error messages to use
> > 
> >         return dev_err_probe(...);
> > 
> > pattern.
> 
> Okay.

Will be result of above fix.

...

> > > +static void pci1xxxx_i2c_remove_pci(struct pci_dev *pdev)
> > > +{
> > > +     struct pci1xxxx_i2c *i2c = pci_get_drvdata(pdev);
> > > +
> > > +     pci1xxxx_i2c_shutdown(i2c);
> > > +}
> > 
> > This will be gone.
> 
> I am not getting this comment also.

See above.

-- 
With Best Regards,
Andy Shevchenko