From b77bd3ba762f34e5eb731134cf50e233d1060053 Mon Sep 17 00:00:00 2001 From: Fabio Estevam Date: Wed, 27 Nov 2024 16:06:05 -0300 Subject: [PATCH 1/2] ARM: imx: Re-introduce the PINCTRL selection Since commit 17d210018914 ("ARM: imx: Allow user to disable pinctrl"), the CONFIG_PINCTRL option is no longer implicitly selected, causing several i.MX SoC pinctrl drivers no longer getting selected by default. This causes boot regressions on the ARMv4, ARMv5, ARMv6 and ARMv7 i.MX SoCs. Fix it by selecting CONFIG_PINCTRL as before. This defeats the purpose of 7d210018914 ("ARM: imx: Allow user to disable pinctrl"), but it is the less invasive fix for the boot regressions. The attempt to build Layerscape without pinctrl can still be explored later as suggested by Arnd: "Overall, my best advice here is still to not change the way i.MX pinctrl works at all, but just fix Layerscape to not depend on i.MX. The reason for the 'select' here is clearly that the i.MX machines would fail to boot without pinctrl, and changing that because of Layerscape seems backwards." Fixes: 17d210018914 ("ARM: imx: Allow user to disable pinctrl") Reported-by: Guenter Roeck Closes: https://lore.kernel.org/linux-arm-kernel/49ff070a-ce67-42d7-84ec-8b54fd7e9742@roeck-us.net/ Signed-off-by: Fabio Estevam Acked-by: Arnd Bergmann Reviewed-by: Linus Walleij Tested-by: Guenter Roeck Link: https://lore.kernel.org/20241127190605.1367157-1-festevam@gmail.com Signed-off-by: Linus Walleij --- arch/arm/mach-imx/Kconfig | 1 + 1 file changed, 1 insertion(+) diff --git a/arch/arm/mach-imx/Kconfig b/arch/arm/mach-imx/Kconfig index e4fe059cd861..dc47b2312127 100644 --- a/arch/arm/mach-imx/Kconfig +++ b/arch/arm/mach-imx/Kconfig @@ -6,6 +6,7 @@ menuconfig ARCH_MXC select CLKSRC_IMX_GPT select GENERIC_IRQ_CHIP select GPIOLIB + select PINCTRL select PM_OPP if PM select SOC_BUS select SRAM From a37eecb705f33726f1fb7cd2a67e514a15dfe693 Mon Sep 17 00:00:00 2001 From: Evgenii Shatokhin Date: Mon, 9 Dec 2024 10:46:59 +0300 Subject: [PATCH 2/2] pinctrl: mcp23s08: Fix sleeping in atomic context due to regmap locking If a device uses MCP23xxx IO expander to receive IRQs, the following bug can happen: BUG: sleeping function called from invalid context at kernel/locking/mutex.c:283 in_atomic(): 1, irqs_disabled(): 1, non_block: 0, ... preempt_count: 1, expected: 0 ... Call Trace: ... __might_resched+0x104/0x10e __might_sleep+0x3e/0x62 mutex_lock+0x20/0x4c regmap_lock_mutex+0x10/0x18 regmap_update_bits_base+0x2c/0x66 mcp23s08_irq_set_type+0x1ae/0x1d6 __irq_set_trigger+0x56/0x172 __setup_irq+0x1e6/0x646 request_threaded_irq+0xb6/0x160 ... We observed the problem while experimenting with a touchscreen driver which used MCP23017 IO expander (I2C). The regmap in the pinctrl-mcp23s08 driver uses a mutex for protection from concurrent accesses, which is the default for regmaps without .fast_io, .disable_locking, etc. mcp23s08_irq_set_type() calls regmap_update_bits_base(), and the latter locks the mutex. However, __setup_irq() locks desc->lock spinlock before calling these functions. As a result, the system tries to lock the mutex whole holding the spinlock. It seems, the internal regmap locks are not needed in this driver at all. mcp->lock seems to protect the regmap from concurrent accesses already, except, probably, in mcp_pinconf_get/set. mcp23s08_irq_set_type() and mcp23s08_irq_mask/unmask() are called under chip_bus_lock(), which calls mcp23s08_irq_bus_lock(). The latter takes mcp->lock and enables regmap caching, so that the potentially slow I2C accesses are deferred until chip_bus_unlock(). The accesses to the regmap from mcp23s08_probe_one() do not need additional locking. In all remaining places where the regmap is accessed, except mcp_pinconf_get/set(), the driver already takes mcp->lock. This patch adds locking in mcp_pinconf_get/set() and disables internal locking in the regmap config. Among other things, it fixes the sleeping in atomic context described above. Fixes: 8f38910ba4f6 ("pinctrl: mcp23s08: switch to regmap caching") Cc: stable@vger.kernel.org Signed-off-by: Evgenii Shatokhin Link: https://lore.kernel.org/20241209074659.1442898-1-e.shatokhin@yadro.com Signed-off-by: Linus Walleij --- drivers/pinctrl/pinctrl-mcp23s08.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/pinctrl/pinctrl-mcp23s08.c b/drivers/pinctrl/pinctrl-mcp23s08.c index d66c3a3e8429..b96e6368a956 100644 --- a/drivers/pinctrl/pinctrl-mcp23s08.c +++ b/drivers/pinctrl/pinctrl-mcp23s08.c @@ -86,6 +86,7 @@ const struct regmap_config mcp23x08_regmap = { .num_reg_defaults = ARRAY_SIZE(mcp23x08_defaults), .cache_type = REGCACHE_FLAT, .max_register = MCP_OLAT, + .disable_locking = true, /* mcp->lock protects the regmap */ }; EXPORT_SYMBOL_GPL(mcp23x08_regmap); @@ -132,6 +133,7 @@ const struct regmap_config mcp23x17_regmap = { .num_reg_defaults = ARRAY_SIZE(mcp23x17_defaults), .cache_type = REGCACHE_FLAT, .val_format_endian = REGMAP_ENDIAN_LITTLE, + .disable_locking = true, /* mcp->lock protects the regmap */ }; EXPORT_SYMBOL_GPL(mcp23x17_regmap); @@ -228,7 +230,9 @@ static int mcp_pinconf_get(struct pinctrl_dev *pctldev, unsigned int pin, switch (param) { case PIN_CONFIG_BIAS_PULL_UP: + mutex_lock(&mcp->lock); ret = mcp_read(mcp, MCP_GPPU, &data); + mutex_unlock(&mcp->lock); if (ret < 0) return ret; status = (data & BIT(pin)) ? 1 : 0; @@ -257,7 +261,9 @@ static int mcp_pinconf_set(struct pinctrl_dev *pctldev, unsigned int pin, switch (param) { case PIN_CONFIG_BIAS_PULL_UP: + mutex_lock(&mcp->lock); ret = mcp_set_bit(mcp, MCP_GPPU, pin, arg); + mutex_unlock(&mcp->lock); break; default: dev_dbg(mcp->dev, "Invalid config param %04x\n", param);