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Date:   Tue, 10 Oct 2023 09:19:27 -0700
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Subject: Re: [PATCH v1 2/4] hte: tegra194: don't access struct gpio_chip
Content-Language: en-US
To:     Andy Shevchenko <andriy.shevchenko@linux.intel.com>,
        Bartosz Golaszewski <bartosz.golaszewski@linaro.org>,
        linux-gpio@vger.kernel.org, linux-kernel@vger.kernel.org,
        timestamp@lists.linux.dev, linux-tegra@vger.kernel.org
Cc:     Linus Walleij <linus.walleij@linaro.org>,
        Bartosz Golaszewski <brgl@bgdev.pl>,
        Andy Shevchenko <andy@kernel.org>,
        Thierry Reding <thierry.reding@gmail.com>,
        Jonathan Hunter <jonathanh@nvidia.com>
References: <20231010151709.4104747-1-andriy.shevchenko@linux.intel.com>
 <20231010151709.4104747-3-andriy.shevchenko@linux.intel.com>
From:   Dipen Patel <dipenp@nvidia.com>
In-Reply-To: <20231010151709.4104747-3-andriy.shevchenko@linux.intel.com>
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On 10/10/23 8:17 AM, Andy Shevchenko wrote:
> From: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
> 
> Using struct gpio_chip is not safe as it will disappear if the
> underlying driver is unbound for any reason. Switch to using reference
> counted struct gpio_device and its dedicated accessors.
> 
> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
> Tested-by: Dipen Patel <dipenp@nvidia.com>
> Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
> [andy: used gpio_device_find_by_fwnode()]
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> ---
>  drivers/hte/hte-tegra194.c | 33 +++++++++++++++++++--------------
>  1 file changed, 19 insertions(+), 14 deletions(-)
> 
> diff --git a/drivers/hte/hte-tegra194.c b/drivers/hte/hte-tegra194.c
> index 9fd3c00ff695..339ff5921ec8 100644
> --- a/drivers/hte/hte-tegra194.c
> +++ b/drivers/hte/hte-tegra194.c
> @@ -132,7 +132,7 @@ struct tegra_hte_soc {
>  	const struct tegra_hte_data *prov_data;
>  	struct tegra_hte_line_data *line_data;
>  	struct hte_chip *chip;
> -	struct gpio_chip *c;
> +	struct gpio_device *gdev;
>  	void __iomem *regs;
>  };
>  
> @@ -421,7 +421,7 @@ static int tegra_hte_line_xlate(struct hte_chip *gc,
>  	 * HTE/GTE namespace.
>  	 */
>  	if (gs->prov_data->type == HTE_TEGRA_TYPE_GPIO && !args) {
> -		line_id = desc->attr.line_id - gs->c->base;
> +		line_id = desc->attr.line_id - gpio_device_get_base(gs->gdev);
>  		map = gs->prov_data->map;
>  		map_sz = gs->prov_data->map_sz;
>  	} else if (gs->prov_data->type == HTE_TEGRA_TYPE_GPIO && args) {
> @@ -643,12 +643,15 @@ static irqreturn_t tegra_hte_isr(int irq, void *dev_id)
>  static bool tegra_hte_match_from_linedata(const struct hte_chip *chip,
>  					  const struct hte_ts_desc *hdesc)
>  {
> +	struct gpio_device *gdev __free(gpio_device_put) = NULL;
>  	struct tegra_hte_soc *hte_dev = chip->data;
>  
>  	if (!hte_dev || (hte_dev->prov_data->type != HTE_TEGRA_TYPE_GPIO))
>  		return false;
>  
> -	return hte_dev->c == gpiod_to_chip(hdesc->attr.line_data);
> +	gdev = gpiod_to_device(hdesc->attr.line_data);
> +
> +	return hte_dev->gdev == gdev;
>  }
>  
>  static const struct of_device_id tegra_hte_of_match[] = {
> @@ -676,14 +679,11 @@ static void tegra_gte_disable(void *data)
>  	tegra_hte_writel(gs, HTE_TECTRL, 0);
>  }
>  
> -static int tegra_get_gpiochip_from_name(struct gpio_chip *chip, void *data)
> +static void tegra_hte_put_gpio_device(void *data)
>  {
> -	return !strcmp(chip->label, data);
> -}
> +	struct gpio_device *gdev = data;
>  
> -static int tegra_gpiochip_match(struct gpio_chip *chip, void *data)
> -{
> -	return chip->fwnode == of_node_to_fwnode(data);
> +	gpio_device_put(gdev);
>  }
>  
>  static int tegra_hte_probe(struct platform_device *pdev)
> @@ -763,8 +763,8 @@ static int tegra_hte_probe(struct platform_device *pdev)
>  
>  		if (of_device_is_compatible(dev->of_node,
>  					    "nvidia,tegra194-gte-aon")) {
> -			hte_dev->c = gpiochip_find("tegra194-gpio-aon",
> -						tegra_get_gpiochip_from_name);
> +			hte_dev->gdev =
> +				gpio_device_find_by_label("tegra194-gpio-aon");
>  		} else {
>  			gpio_ctrl = of_parse_phandle(dev->of_node,
>  						     "nvidia,gpio-controller",
> @@ -775,14 +775,19 @@ static int tegra_hte_probe(struct platform_device *pdev)
>  				return -ENODEV;
>  			}
>  
> -			hte_dev->c = gpiochip_find(gpio_ctrl,
> -						   tegra_gpiochip_match);
> +			hte_dev->gdev =
> +				gpio_device_find_by_fwnode(of_fnode_handle(gpio_ctrl));
>  			of_node_put(gpio_ctrl);
>  		}
>  
> -		if (!hte_dev->c)
> +		if (!hte_dev->gdev)
>  			return dev_err_probe(dev, -EPROBE_DEFER,
>  					     "wait for gpio controller\n");
> +
> +		ret = devm_add_action_or_reset(dev, tegra_hte_put_gpio_device,
> +					       hte_dev->gdev);
> +		if (ret)
> +			return ret;
>  	}
>  
>  	hte_dev->chip = gc;

Looks good to me, I will wait for others to comment and will test out (2,3,4
also) probably end of the day 11th Oct.