Re: [PATCH v2 3/4] gpio: adp5585: Add Analog Devices ADP5585 support

From: Laurent Pinchart
Date: Tue May 28 2024 - 16:21:06 EST


Hi Andy,

Thank you for the patch.

On Tue, May 28, 2024 at 10:36:06PM +0300, Andy Shevchenko wrote:
> Tue, May 28, 2024 at 10:03:13PM +0300, Laurent Pinchart kirjoitti:
> > From: Haibo Chen <haibo.chen@xxxxxxx>
> >
> > The ADP5585 is a 10/11 input/output port expander with a built in keypad
> > matrix decoder, programmable logic, reset generator, and PWM generator.
> > This driver supports the GPIO function using the platform device
> > registered by the core MFD driver.
> >
> > The driver is derived from an initial implementation from NXP, available
> > in commit 451f61b46b76 ("MLK-25917-2 gpio: adp5585-gpio: add
> > adp5585-gpio support") in their BSP kernel tree. It has been extensively
> > rewritten.
>
> Why is this not using gpio-regmap?
>
> ...
>
> > +#include <linux/device.h>
> > +#include <linux/gpio/driver.h>
> > +#include <linux/mfd/adp5585.h>
> > +#include <linux/module.h>
> > +#include <linux/platform_device.h>
> > +#include <linux/regmap.h>
>
> + types.h
>
> ...
>
> > + bit = off * 2 + (off > 5 ? 4 : 0);
>
> Right, but can you use >= 6 here which immediately follows to the next
> question, i.e. why not use bank in this conditional?

The ADP5585_BANK() macro is meant to be used with ADP5585_BIT(), for a
set of registers with the same layout. Here the layout is different, the
registers contain multi-bit fields. I can't use ADP5585_BIT(), so I'd
rather not use ADP5585_BANK() either. I have decided to use > 5 instead
of >= 6 to match the R5 field name in the comment above:

/*
* The bias configuration fields are 2 bits wide and laid down in
* consecutive registers ADP5585_RPULL_CONFIG_*, with a hole of 4 bits
* after R5.
*/

> ...
>
> > + struct adp5585_dev *adp5585 = dev_get_drvdata(pdev->dev.parent);
>
> (see below)
>
> > + struct adp5585_gpio_dev *adp5585_gpio;
> > + struct device *dev = &pdev->dev;
>
> struct adp5585_dev *adp5585 = dev_get_drvdata(dev->parent);

I prefer keeping the current ordering, with long lines first, I think
that's more readable.

> > + struct gpio_chip *gc;
> > + int ret;
>
> ...
>
> > + platform_set_drvdata(pdev, adp5585_gpio);
>
> Any use of driver data?

In v1, not v2. I'll drop it.

> ...
>
> > + device_set_of_node_from_dev(dev, dev->parent);
>
> Why not device_set_node()?

Because device_set_of_node_from_dev() is meant for this exact use case,
where the same node is used for multiple devices. It also puts any
previous dev->of_node, ensuring proper refcounting when devices are
unbound and rebound, without being deleted.

--
Regards,

Laurent Pinchart