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The shared GPIO descriptor used either a mutex or a spinlock, chosen at runtime from the underlying chip's can_sleep: shared_desc->can_sleep = gpiod_cansleep(shared_desc->desc); ... if (can_sleep) mutex_lock(); else spin_lock_irqsave(); can_sleep describes only the value path (->get/->set). Under the same lock, however, the proxy may call gpiod_set_config() and gpiod_direction_*(), which can reach pinctrl paths that take a mutex (e.g. gpiod_set_config() -> gpiochip_generic_config() -> pinctrl_gpio_set_config()), independent of can_sleep. On a controller with non-sleeping MMIO value ops the descriptor lock was a spinlock, so the sleeping pinctrl call ran from atomic context. Reproduced on an Amlogic A113X board with the workaround from commit28f2406838("pinctrl: meson: mark the GPIO controller as sleeping") reverted; the original Khadas VIM3 report hit the same path: BUG: sleeping function called from invalid context __mutex_lock pinctrl_get_device_gpio_range pinctrl_gpio_set_config gpiochip_generic_config gpiod_set_config gpio_shared_proxy_set_config <- voting spinlock held ... mmc_pwrseq_simple_probe The spinlock existed to take the value vote from atomic context, but the vote and the (possibly sleeping) control operations share the same state and lock, so this scheme cannot serialize config under a mutex and still offer atomic value access. Always serialize the shared descriptor with a mutex instead and mark the proxy a sleeping gpiochip, driving the underlying GPIO through the cansleep value accessors: those are valid for both sleeping and non-sleeping chips, so value access keeps working on fast controllers, at the cost of no longer being atomic. With every vote edge now driven through the cansleep value setter, gpio_shared_proxy_set_unlocked() no longer needs a per-call setter: drop its set_func callback and call gpiod_set_value_cansleep() directly. The shared direction_output path reaches it only once the line is already an output, so driving the value there is equivalent to re-issuing gpiod_direction_output(), without the redundant per-edge re-assertion of drive config and bias. This is observable: consumers gating on gpiod_cansleep() take their sleeping branch on a proxied GPIO (mmc-pwrseq-emmc skips its emergency-restart reset handler; its normal reset is unaffected), and consumers that reject sleeping GPIOs (pwm-gpio, ps2-gpio, ...) would fail to probe. Such atomic users do not share a pin through the proxy, whose purpose is voting on shared reset/enable lines. The same narrowing already applies on Amlogic since that workaround, and rockchip addressed the identical splat per-driver in commit7ca497be00("gpio: rockchip: Stop calling pinctrl for set_direction"); fixing the proxy addresses the locking error once, for every controller. The lock type was added by commita060b8c511("gpiolib: implement low-level, shared GPIO support"); the sleeping call under it arrived with the proxy driver. Fixes:e992d54c6f("gpio: shared-proxy: implement the shared GPIO proxy driver") Reported-by: Marek Szyprowski <m.szyprowski@samsung.com> Closes: https://lore.kernel.org/all/00107523-7737-4b92-a785-14ce4e93b8cb@samsung.com/ Signed-off-by: Viacheslav Bocharov <v@baodeep.com> Link: https://patch.msgid.link/20260630101545.800625-2-v@baodeep.com Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@oss.qualcomm.com>
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