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Date: Tue, 23 Apr 2024 15:59:42 +0300
From: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
To: Linus Walleij <linus.walleij@linaro.org>
Cc: Kalle Valo <kvalo@kernel.org>, Arnd Bergmann <arnd@arndb.de>,
	Alban Bedel <albeu@free.fr>, Bartosz Golaszewski <brgl@bgdev.pl>,
	Toke =?iso-8859-1?Q?H=F8iland-J=F8rgensen?= <toke@toke.dk>,
	linux-wireless@vger.kernel.org, brcm80211-dev-list.pdl@broadcom.com,
	linux-gpio@vger.kernel.org
Subject: Re: [PATCH v2] wifi: ath9k: Obtain system GPIOS from descriptors
Message-ID: <Ziewvkh_Hd2j5hHF@smile.fi.intel.com>
References: <20240423-descriptors-wireless-v2-1-6d1d03b30bfa@linaro.org>
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In-Reply-To: <20240423-descriptors-wireless-v2-1-6d1d03b30bfa@linaro.org>
Organization: Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo

On Tue, Apr 23, 2024 at 02:12:33PM +0200, Linus Walleij wrote:
> The ath9k has an odd use of system-wide GPIOs: if the chip
> does not have internal GPIO capability, it will try to obtain a
> GPIO line from the system GPIO controller:
> 
>   if (BIT(gpio) & ah->caps.gpio_mask)
>         ath9k_hw_gpio_cfg_wmac(...);
>   else if (AR_SREV_SOC(ah))
>         ath9k_hw_gpio_cfg_soc(ah, gpio, out, label);
> 
> Where ath9k_hw_gpio_cfg_soc() will attempt to issue
> gpio_request_one() passing the local GPIO number of the controller
> (0..31) to gpio_request_one().
> 
> This is somewhat peculiar and possibly even dangerous: there is
> nowadays no guarantee of the numbering of these system-wide
> GPIOs, and assuming that GPIO 0..31 as used by ath9k would
> correspond to GPIOs 0..31 on the system as a whole seems a bit
> wild.
> 
> Register all 32 GPIOs at index 0..31 directly in the ATH79K
> GPIO driver and associate with WIFI if and only if we are probing
> ATH79K wifi from the AHB bus (used for SoCs).

...

> +/*
> + * This registers all of the ath79k GPIOs as descriptors to be picked
> + * directly from the ATH79K wifi driver if the two are jitted together
> + * in the same SoC.
> + */
> +#define ATH79K_WIFI_DESCS 32
> +static int ath79_gpio_register_wifi_descriptors(struct device *dev,
> +						const char *label)
> +{
> +	struct gpiod_lookup_table *lookup;
> +	int i;

unsigned ?

> +	/* Create a gpiod lookup using gpiochip-local offsets + 1 for NULL */
> +        lookup = devm_kzalloc(dev,
> +			      struct_size(lookup, table, ATH79K_WIFI_DESCS + 1),
> +			      GFP_KERNEL);

> +

Besides unneeded blank line the above has a broken indentation.

> +	if (!lookup)
> +		return -ENOMEM;
> +
> +	lookup->dev_id = "ath9k";
> +
> +	for (i = 0; i < ATH79K_WIFI_DESCS; i++) {

> +		lookup->table[i] = (struct gpiod_lookup)

This is not needed as GPIO_LOOKUP_IDX() is a compound literal.

> +			GPIO_LOOKUP_IDX(label, 0, NULL, i,
> +					GPIO_ACTIVE_HIGH);

Hence:

		lookup->table[i] =
			GPIO_LOOKUP_IDX(label, 0, NULL, i, GPIO_ACTIVE_HIGH);

> +	}
> +
> +	gpiod_add_lookup_table(lookup);
> +
> +	return 0;
> +}

...

> +	/* Obtains a system specific GPIO descriptor from another GPIO controller */
> +	gpiod = devm_gpiod_get_index(ah->dev, NULL, gpio, flags);

> +

Unneeded blank line.

> +	if (IS_ERR(gpiod)) {
> +		err = PTR_ERR(gpiod);
>  		ath_err(ath9k_hw_common(ah), "request GPIO%d failed:%d\n",
>  			gpio, err);
>  		return;
>  	}

-- 
With Best Regards,
Andy Shevchenko