linux-kernel - [PATCH] gpiolib: fix allocation of mixed dynamic/static GPIOs

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Date:   Thu, 27 Apr 2023 00:03:38 +0200
From:   Andreas Kemnade <andreas@...nade.info>
To:     linus.walleij@...aro.org, brgl@...ev.pl,
        christophe.leroy@...roup.eu, andy.shevchenko@...il.com,
        linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org,
        ": Tony Lindgren" <tony@...mide.com>,
        Aaro Koskinen <aaro.koskinen@....fi>,
        linux-omap@...r.kernel.org
Cc:     Andreas Kemnade <andreas@...nade.info>
Subject: [PATCH] gpiolib: fix allocation of mixed dynamic/static GPIOs

If static allocation and dynamic allocation GPIOs are present,
dynamic allocation pollutes the numberspace for static allocation,
causing static allocation to fail.
Enfore dynamic allocation above GPIO_DYNAMIC_BASE.

Seen on a GTA04 when omap-gpio (static) and twl-gpio (dynamic)
raced.
On that device it is fixed invasively by
commit 92bf78b33b0b4 ("gpio: omap: use dynamic allocation of base")
but lets also fix that for devices where there is still
a mixture of static and dynamic allocation.

Fixes: 7b61212f2a07 ("gpiolib: Get rid of ARCH_NR_GPIOS")
Suggested-by: andy.shevchenko@...il.com
Signed-off-by: Andreas Kemnade <andreas@...nade.info>
---
 drivers/gpio/gpiolib.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 19bd23044b017..18b68d0aec7db 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -188,6 +188,10 @@ static int gpiochip_find_base(int ngpio)
 	int base = GPIO_DYNAMIC_BASE;
 
 	list_for_each_entry(gdev, &gpio_devices, list) {
+		/* do not pollute area for static allocation */
+		if (gdev->base < GPIO_DYNAMIC_BASE)
+			continue;
+
 		/* found a free space? */
 		if (gdev->base >= base + ngpio)
 			break;
-- 
2.39.2