linux-kernel - [PATCH RFC/RFT] pinctrl: qcom: make the pinmuxing strict

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Message-ID: <20250625153711.194208-1-brgl@bgdev.pl>
Date: Wed, 25 Jun 2025 17:37:11 +0200
From: Bartosz Golaszewski <brgl@...ev.pl>
To: Bjorn Andersson <andersson@...nel.org>,
	Linus Walleij <linus.walleij@...aro.org>,
	Konrad Dybcio <konradybcio@...nel.org>
Cc: linux-arm-msm@...r.kernel.org,
	linux-gpio@...r.kernel.org,
	linux-kernel@...r.kernel.org,
	Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: [PATCH RFC/RFT] pinctrl: qcom: make the pinmuxing strict

From: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>

The strict flag in struct pinmux_ops disallows the usage of the same pin
as a GPIO and for another function. Without it, a rouge user-space
process with enough privileges (or even a buggy driver) can request a
used pin as GPIO and drive it, potentially confusing devices or even
crashing the system. Set it globally for all pinctrl-msm users.

Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
---
Having discussed this with Bjorn and Konrad - it seems the consensus is
that it makes sense to set this flag in pinctrl-msm. I'm marking this
patch as an RFC/RFT as I'm a bit afraid existing use-cases could break
with it but I suggest we give it a shot and see what happens.

 drivers/pinctrl/qcom/pinctrl-msm.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/pinctrl/qcom/pinctrl-msm.c b/drivers/pinctrl/qcom/pinctrl-msm.c
index f713c80d7f3ed..b78492dc05adc 100644
--- a/drivers/pinctrl/qcom/pinctrl-msm.c
+++ b/drivers/pinctrl/qcom/pinctrl-msm.c
@@ -293,6 +293,7 @@ static const struct pinmux_ops msm_pinmux_ops = {
 	.get_function_groups	= msm_get_function_groups,
 	.gpio_request_enable	= msm_pinmux_request_gpio,
 	.set_mux		= msm_pinmux_set_mux,
+	.strict			= true,
 };
 
 static int msm_config_reg(struct msm_pinctrl *pctrl,
-- 
2.48.1