linux-kernel - Re: [PATCH] gpio: brcmstb: allow 0 width GPIO banks

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Date:   Wed, 15 Aug 2018 17:14:05 -0700
From:   Florian Fainelli <f.fainelli@...il.com>
To:     justinpopo6@...il.com, linux-gpio@...r.kernel.org
Cc:     linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
        bcm-kernel-feedback-list@...adcom.com, f.fainelli@...il.com,
        computersforpeace@...il.com, linus.walleij@...aro.org,
        gregory.0xf0@...il.com
Subject: Re: [PATCH] gpio: brcmstb: allow 0 width GPIO banks

On 08/14/2018 04:31 PM, justinpopo6@...il.com wrote:
> From: Justin Chen <justinpopo6@...il.com>
> 
> Sometimes we have empty banks within the GPIO block. This commit allows
> proper handling of 0 width GPIO banks. We handle 0 width GPIO banks by
> incrementing the bank and number of GPIOs, but not initializing them.
> This will mean a call into the non-existent GPIOs will return an error.
> 
> Also remove banks and GPIO information from the dev_info print. This
> information is misleading since the incremented banks and gpio_base do
> not reflect the actual GPIOs that got initialized. We leave this
> information out since it is already printed with dev_dbg.
> 
> Signed-off-by: Justin Chen <justinpopo6@...il.com>
> ---
>  drivers/gpio/gpio-brcmstb.c | 15 +++++++++++++--
>  1 file changed, 13 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpio/gpio-brcmstb.c b/drivers/gpio/gpio-brcmstb.c
> index 16c7f9f..8658910 100644
> --- a/drivers/gpio/gpio-brcmstb.c
> +++ b/drivers/gpio/gpio-brcmstb.c
> @@ -664,6 +664,18 @@ static int brcmstb_gpio_probe(struct platform_device *pdev)
>  		struct brcmstb_gpio_bank *bank;
>  		struct gpio_chip *gc;
>  
> +		/*
> +		 * If bank_width is 0, then there is an empty bank in the
> +		 * register block. Special handling for this case.
> +		 */
> +		if (bank_width == 0) {
> +			dev_dbg(dev, "Width 0 found: Empty bank @ %d\n",
> +					num_banks);

Stylistic nit: you would want the second line to be aligned at the start
of the opening parenthesis

> +			num_banks++;
> +			gpio_base += MAX_GPIO_PER_BANK;
> +			continue;
> +		}
> +
>  		bank = devm_kzalloc(dev, sizeof(*bank), GFP_KERNEL);
>  		if (!bank) {
>  			err = -ENOMEM;
> @@ -740,8 +752,7 @@ static int brcmstb_gpio_probe(struct platform_device *pdev)
>  			goto fail;
>  	}
>  
> -	dev_info(dev, "Registered %d banks (GPIO(s): %d-%d)\n",
> -			num_banks, priv->gpio_base, gpio_base - 1);
> +	dev_info(dev, "Brcmstb GPIO registered\n");

Not sure if there much value in preserving that message anymore, if the
controller is not there, nothing will show up in /sys/class/gpio, so you
would pretty quickly find out that something went wrong?

>  
>  	if (priv->parent_wake_irq && need_wakeup_event)
>  		pm_wakeup_event(dev, 0);
> 


-- 
Florian