linux-kernel - [PATCH 4.4 119/137] gpio: mpc8xxx: Dont overwrite default irq_set

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Date:   Thu,  2 Jan 2020 23:08:12 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Vladimir Oltean <vladimir.oltean@....com>,
        Michael Walle <michael@...le.cc>,
        Linus Walleij <linus.walleij@...aro.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.4 119/137] gpio: mpc8xxx: Dont overwrite default irq_set_type callback

From: Vladimir Oltean <vladimir.oltean@....com>

[ Upstream commit 4e50573f39229d5e9c985fa3b4923a8b29619ade ]

The per-SoC devtype structures can contain their own callbacks that
overwrite mpc8xxx_gpio_devtype_default.

The clear intention is that mpc8xxx_irq_set_type is used in case the SoC
does not specify a more specific callback. But what happens is that if
the SoC doesn't specify one, its .irq_set_type is de-facto NULL, and
this overwrites mpc8xxx_irq_set_type to a no-op. This means that the
following SoCs are affected:

- fsl,mpc8572-gpio
- fsl,ls1028a-gpio
- fsl,ls1088a-gpio

On these boards, the irq_set_type does exactly nothing, and the GPIO
controller keeps its GPICR register in the hardware-default state. On
the LS1028A, that is ACTIVE_BOTH, which means 2 interrupts are raised
even if the IRQ client requests LEVEL_HIGH. Another implication is that
the IRQs are not checked (e.g. level-triggered interrupts are not
rejected, although they are not supported).

Fixes: 82e39b0d8566 ("gpio: mpc8xxx: handle differences between incarnations at a single place")
Signed-off-by: Vladimir Oltean <vladimir.oltean@....com>
Link: https://lore.kernel.org/r/20191115125551.31061-1-olteanv@gmail.com
Tested-by: Michael Walle <michael@...le.cc>
Signed-off-by: Linus Walleij <linus.walleij@...aro.org>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/gpio/gpio-mpc8xxx.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/gpio/gpio-mpc8xxx.c b/drivers/gpio/gpio-mpc8xxx.c
index 9e02cb6afb0b..ce6e15167d0b 100644
--- a/drivers/gpio/gpio-mpc8xxx.c
+++ b/drivers/gpio/gpio-mpc8xxx.c
@@ -409,7 +409,8 @@ static int mpc8xxx_probe(struct platform_device *pdev)
 	 * It's assumed that only a single type of gpio controller is available
 	 * on the current machine, so overwriting global data is fine.
 	 */
-	mpc8xxx_irq_chip.irq_set_type = devtype->irq_set_type;
+	if (devtype->irq_set_type)
+		mpc8xxx_irq_chip.irq_set_type = devtype->irq_set_type;

 	gc->direction_output = devtype->gpio_dir_out ?: mpc8xxx_gpio_dir_out;
 	gc->get = devtype->gpio_get ?: mpc8xxx_gpio_get;
-- 
2.20.1