linux-kernel - Re: [PATCH v3 1/2] gpio: tps65219: add GPIO support for TPS65219 PMIC

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Message-ID: <ZHD3VtFDYUyy_Std@surfacebook>
Date:   Fri, 26 May 2023 21:15:50 +0300
From:   andy.shevchenko@...il.com
To:     Jerome Neanne <jneanne@...libre.com>
Cc:     Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <brgl@...ev.pl>,
        Tony Lindgren <tony@...mide.com>, Lee Jones <lee@...nel.org>,
        linux-kernel@...r.kernel.org, linux-gpio@...r.kernel.org,
        linux-omap@...r.kernel.org,
        Jonathan Cormier <jcormier@...ticallink.com>
Subject: Re: [PATCH v3 1/2] gpio: tps65219: add GPIO support for TPS65219 PMIC

Fri, May 26, 2023 at 05:06:03PM +0200, Jerome Neanne kirjoitti:
> Add support for TPS65219 PMICs GPIO interface.
> 
> 3 GPIO pins:
> - GPIO0 only is IO but input mode reserved for MULTI_DEVICE_ENABLE usage
> - GPIO1 and GPIO2 are Output only and referred as GPO1 and GPO2 in spec
> 
> GPIO0 is statically configured as input or output prior to Linux boot.
> it is used for MULTI_DEVICE_ENABLE function.
> This setting is statically configured by NVM.
> GPIO0 can't be used as a generic GPIO (specification Table 8-34).
> It's either a GPO when MULTI_DEVICE_EN=0,
> or a GPI when MULTI_DEVICE_EN=1.

> Datasheet describes specific usage for non standard GPIO.

> Link: https://www.ti.com/lit/ds/symlink/tps65219.pdf
> 

This blank line makes Link: above not to be a tag. Tag block mustn't have blank
lines. OTOH, the other text must be delimited by a blank line before the tag
block. That said, move this blank line to before Link: line.

> Co-developed-by: Jonathan Cormier <jcormier@...ticallink.com>
> Signed-off-by: Jonathan Cormier <jcormier@...ticallink.com>
> Signed-off-by: Jerome Neanne <jneanne@...libre.com>

...

> +	help
> +	  Select this option to enable GPIO driver for the TPS65219
> +	  chip family.
> +	  GPIO0 is statically configured as input or output prior to Linux boot.
> +	  it is used for MULTI_DEVICE_ENABLE function.
> +	  This setting is statically configured by NVM.
> +	  GPIO0 can't be used as a generic GPIO.
> +	  It's either a GPO when MULTI_DEVICE_EN=0,
> +	  or a GPI when MULTI_DEVICE_EN=1.

This is strange indentation, we have longer lines, why not using all room
available? Btw, seems the commit message itself has the same issue.

> +	  This driver can also be built as a module. If so, the
> +	  module will be called gpio_tps65219.

...

Missing bits.h

> +#include <linux/gpio/driver.h>
> +#include <linux/mfd/tps65219.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/regmap.h>

...

> +static int tps65219_gpio_get(struct gpio_chip *gc, unsigned int offset)
> +{
> +	struct tps65219_gpio *gpio = gpiochip_get_data(gc);

With

	struct device *dev = gpio->tps->dev;

you may make some code blocks shorter.

> +	int ret, val;
> +
> +	if (offset != TPS65219_GPIO0_IDX) {
> +		dev_err(gpio->tps->dev,
> +			"GPIO%d is output only, cannot get\n",
> +			offset);

Like here.

> +		return -EOPNOTSUPP;
> +	}
> +
> +	ret = regmap_read(gpio->tps->regmap, TPS65219_REG_MFP_CTRL, &val);
> +	if (ret)
> +		return ret;
> +
> +	dev_warn(gpio->tps->dev,
> +		 "GPIO%d = %d, used for MULTI_DEVICE_ENABLE, not as standard GPIO\n",

> +		 offset, !!(val & BIT(TPS65219_MFP_GPIO_STATUS_MASK)));

Isn't it the same...

> +	/* depends on NVM config return error if dir output else the GPIO0 status bit */
> +	if (tps65219_gpio_get_direction(gc, offset) == TPS65219_GPIO_DIR_OUT)
> +		return -EOPNOTSUPP;
> +
> +	return !!(val & BIT(TPS65219_MFP_GPIO_STATUS_MASK));

...as this one? What the point to evaluate it twice?

> +}

...

> +		dev_err(gpio->tps->dev, "GPIO%d, set to value %d failed.\n", offset, value);

Yeah, there is an inconsistency between line lengths in different functions.
Define for yourself the style 80 or 100 and use it everywhere.

...

> +	/* Documentation is stating that GPIO0 direction must not be changed in Linux:
> +	 * Table 8-34. MFP_1_CONFIG(3): MULTI_DEVICE_ENABLE,
> +	 * Should only be changed in INITIALIZE state (prior to ON Request).
> +	 * Set statically by NVM, changing direction in application can cause a hang.
> +	 * Below can be used for test purpose only:
> +	 */
> +

/*
 * The style of multi-line comment
 * is incorrect. See this example.
 * Besides that, remove unneeded
 * blank line above.
 */

> +	if (IS_ENABLED(DEBUG)) {
> +		int ret = regmap_update_bits(gpio->tps->regmap, TPS65219_REG_MFP_1_CONFIG,
> +					     TPS65219_GPIO0_DIR_MASK, direction);
> +		if (ret) {
> +			dev_err(gpio->tps->dev,

> +				"DEBUG enabled: Fail to change direction to %u for GPIO%d. \
> +				For test only\n",

Do not split string literals on non-\n characters.

> +				direction, offset);

> +		return ret;

Wrong indentation.

> +		}
> +	}

-- 
With Best Regards,
Andy Shevchenko