linux-kernel - Re: [PATCH] gpiolib: of: fix lookup quirk for MIPS Lantiq

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Date: Mon, 01 Jul 2024 08:12:17 +0200
From: Martin Schiller <ms@....tdt.de>
To: Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc: Linus Walleij <linus.walleij@...aro.org>, Bartosz Golaszewski
 <brgl@...ev.pl>, Hauke Mehrtens <hauke@...ke-m.de>, Thomas Bogendoerfer
 <tsbogend@...ha.franken.de>, linux-gpio@...r.kernel.org,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH] gpiolib: of: fix lookup quirk for MIPS Lantiq

On 2024-06-28 20:35, Dmitry Torokhov wrote:
> As it turns out, there is a large number of out-of-tree DTSes (in
> OpenWrt project) that used to specify incorrect (active high) polarity
> for the Lantiq reset GPIO, so to keep compatibility while they are
> being updated a quirk for force the polarity low is needed. Luckily
> these old DTSes used nonstandard name for the property ("gpio-reset" vs
> "reset-gpios") so the quirk will not hurt if there are any new devices
> that need inverted polarity as they can specify the right polarity in
> their DTS when using the standard "reset-gpios" property.
> 
> Additionally the condition to enable the translation from standard to
> non-standard reset GPIO property name was inverted and the replacement
> name for the property was not correct. Fix this as well.
> 
> Fixes: fbbbcd177a27 ("gpiolib: of: add quirk for locating reset lines
> with legacy bindings")
> Fixes: 90c2d2eb7ab5 ("MIPS: pci: lantiq: switch to using gpiod API")
> Reported-by: Martin Schiller <ms@....tdt.de>
> Signed-off-by: Dmitry Torokhov <dmitry.torokhov@...il.com>
> ---
>  drivers/gpio/gpiolib-of.c | 14 ++++++++++++--
>  1 file changed, 12 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpio/gpiolib-of.c b/drivers/gpio/gpiolib-of.c
> index 59c7f8a2431a..d21085830632 100644
> --- a/drivers/gpio/gpiolib-of.c
> +++ b/drivers/gpio/gpiolib-of.c
> @@ -203,6 +203,16 @@ static void of_gpio_try_fixup_polarity(const
> struct device_node *np,
>  		 */
>  		{ "qi,lb60",		"rb-gpios",	true },
>  #endif
> +#if IS_ENABLED(CONFIG_PCI_LANTIQ)
> +		/*
> +		 * According to the PCI specification, the RST# pin is an
> +		 * active-low signal. However, most of the device trees that
> +		 * have been widely used for a long time incorrectly describe
> +		 * reset GPIO as active-high, and were also using wrong name
> +		 * for the property.
> +		 */
> +		{ "lantiq,pci-xway",	"gpio-reset",	false },
> +#endif
>  #if IS_ENABLED(CONFIG_TOUCHSCREEN_TSC2005)
>  		/*
>  		 * DTS for Nokia N900 incorrectly specified "active high"
> @@ -512,9 +522,9 @@ static struct gpio_desc
> *of_find_gpio_rename(struct device_node *np,
>  		{ "reset",	"reset-n-io",	"marvell,nfc-uart" },
>  		{ "reset",	"reset-n-io",	"mrvl,nfc-uart" },
>  #endif
> -#if !IS_ENABLED(CONFIG_PCI_LANTIQ)
> +#if IS_ENABLED(CONFIG_PCI_LANTIQ)
>  		/* MIPS Lantiq PCI */
> -		{ "reset",	"gpios-reset",	"lantiq,pci-xway" },
> +		{ "reset",	"gpio-reset",	"lantiq,pci-xway" },
>  #endif
> 
>  		/*
> --
> 2.45.2.803.g4e1b14247a-goog

Acked-by: Martin Schiller <ms@....tdt.de>