From: Peng Fan peng.fan@nxp.com
[ Upstream commit 20117cf426b677e7aced4e7a1b2b37f6080a46dc ]
Kernel warns about mutable irq_chips: "not an immutable chip, please consider fixing!"
Constify pxa_muxed_gpio_chip, flag the irq_chip as IRQCHIP_IMMUTABLE, add the new helper functions, and call the appropriate gpiolib functions.
Signed-off-by: Peng Fan peng.fan@nxp.com Reviewed-by: Linus Walleij linus.walleij@linaro.org Link: https://lore.kernel.org/r/20250509-gpio-v1-9-639377c98288@nxp.com Signed-off-by: Bartosz Golaszewski bartosz.golaszewski@linaro.org Signed-off-by: Sasha Levin sashal@kernel.org ---
**YES** This commit should be backported to stable kernel trees. Here's my extensive analysis: ## Backport Analysis: gpio: pxa: Make irq_chip immutable ### Code Changes Analysis The commit makes three key changes to `drivers/gpio/gpio-pxa.c`: 1. **Makes irq_chip structure const**: Changes `static struct irq_chip pxa_muxed_gpio_chip` to `static const struct irq_chip pxa_muxed_gpio_chip` 2. **Adds IRQCHIP_IMMUTABLE flag**: Includes `.flags = IRQCHIP_IMMUTABLE` in the irq_chip structure 3. **Adds resource helper macros**: Includes `GPIOCHIP_IRQ_RESOURCE_HELPERS` macro 4. **Updates mask/unmask functions**: Adds proper `gpiochip_disable_irq()` and `gpiochip_enable_irq()` calls in the mask and unmask functions respectively ### Why This Should Be Backported **1. Follows Established Pattern** This commit follows the exact same pattern as the reference commits marked "YES" for backporting: - Similar to gpio-vf610 (commit e6ef4f8ede09) which was backported - Identical to gpio-104-idio-16 (commit 410a5041aa60) which was backported - Same transformation pattern as dozens of other GPIO drivers **2. Fixes Kernel Warning** The commit explicitly addresses a kernel warning: "not an immutable chip, please consider fixing!" This is the same warning addressed in all the reference "YES" commits. **3. Small, Contained Changes** - Only modifies one file (`drivers/gpio/gpio-pxa.c`) - Changes are minimal and mechanical - No architectural changes or new features - Low risk of introducing regressions **4. Important Bug Fix for Users** - Eliminates annoying kernel warnings that users encounter - Brings driver in compliance with modern kernel IRQ subsystem requirements - Improves system reliability by preventing dynamic modification of irq_chip callbacks **5. No Side Effects** - The changes are purely structural improvements - Maintains identical functionality - Does not change the driver's external behavior - Only makes the irq_chip structure immutable for safety **6. Critical Subsystem Compliance** - GPIO subsystem actively enforces immutable irq_chips - This is part of a kernel-wide migration to improve memory safety - Prevents potential security issues from dynamic irq_chip modification **7. Hardware Support Impact** The PXA GPIO driver supports widely-used ARM processors: - Intel PXA25x, PXA26x, PXA27x, PXA3xx series - Marvell PXA93x, MMP, MMP2, PXA1928 series - These are found in many embedded systems and IoT devices ### Comparison with Current Tree The analysis shows that in the current kernel tree (`/home/sasha/linux/`), the gpio-pxa.c driver still has the old mutable irq_chip structure (line 523: `static struct irq_chip pxa_muxed_gpio_chip`), while the target directory shows it has already been converted. This confirms this is a legitimate conversion commit that needs backporting. ### Risk Assessment **Very Low Risk:** - Mechanical transformation following established pattern - No functional changes to GPIO operations - Extensive precedent from similar successful backports - Changes are compile-time enforced (const keyword) This commit represents a straightforward compliance fix that eliminates user- visible warnings while improving code safety, making it an ideal candidate for stable tree backporting.
drivers/gpio/gpio-pxa.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/drivers/gpio/gpio-pxa.c b/drivers/gpio/gpio-pxa.c index cae9661862fe1..0e9f3baf1bd31 100644 --- a/drivers/gpio/gpio-pxa.c +++ b/drivers/gpio/gpio-pxa.c @@ -497,6 +497,8 @@ static void pxa_mask_muxed_gpio(struct irq_data *d) gfer = readl_relaxed(base + GFER_OFFSET) & ~GPIO_bit(gpio); writel_relaxed(grer, base + GRER_OFFSET); writel_relaxed(gfer, base + GFER_OFFSET); + + gpiochip_disable_irq(&pchip->chip, gpio); }
static int pxa_gpio_set_wake(struct irq_data *d, unsigned int on) @@ -516,17 +518,21 @@ static void pxa_unmask_muxed_gpio(struct irq_data *d) unsigned int gpio = irqd_to_hwirq(d); struct pxa_gpio_bank *c = gpio_to_pxabank(&pchip->chip, gpio);
+ gpiochip_enable_irq(&pchip->chip, gpio); + c->irq_mask |= GPIO_bit(gpio); update_edge_detect(c); }
-static struct irq_chip pxa_muxed_gpio_chip = { +static const struct irq_chip pxa_muxed_gpio_chip = { .name = "GPIO", .irq_ack = pxa_ack_muxed_gpio, .irq_mask = pxa_mask_muxed_gpio, .irq_unmask = pxa_unmask_muxed_gpio, .irq_set_type = pxa_gpio_irq_type, .irq_set_wake = pxa_gpio_set_wake, + .flags = IRQCHIP_IMMUTABLE, + GPIOCHIP_IRQ_RESOURCE_HELPERS, };
static int pxa_gpio_nums(struct platform_device *pdev)