From: Radim Pavlik <radim.pavlik@xxxxxxxxxxxxxxxxxx> [ Upstream commit 897120d41e7afd9da435cb00041a142aeeb53c07 ] Checking value of MCP_INTF in mcp23s08_irq suggests that the handler may be called even when there is no interrupt pending. But the actual interrupt could happened between reading MCP_INTF and MCP_GPIO. In this situation we got nothing from MCP_INTF, but the event gets acknowledged on the expander by reading MCP_GPIO. This leads to losing events. Fix the problem by not reading any register until we see something in MCP_INTF. The error was reproduced and fix tested on MCP23017. Signed-off-by: Radim Pavlik <radim.pavlik@xxxxxxxxxxxxxxxxxx> Link: https://lore.kernel.org/r/AM7PR06MB6769E1183F68DEBB252F665ABA3E9@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx Signed-off-by: Linus Walleij <linus.walleij@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> --- drivers/pinctrl/pinctrl-mcp23s08.c | 10 +++++----- 1 file changed, 5 insertions(+), 5 deletions(-) diff --git a/drivers/pinctrl/pinctrl-mcp23s08.c b/drivers/pinctrl/pinctrl-mcp23s08.c index ce2d8014b7e0..799d596a1a4b 100644 --- a/drivers/pinctrl/pinctrl-mcp23s08.c +++ b/drivers/pinctrl/pinctrl-mcp23s08.c @@ -351,6 +351,11 @@ static irqreturn_t mcp23s08_irq(int irq, void *data) if (mcp_read(mcp, MCP_INTF, &intf)) goto unlock; + if (intf == 0) { + /* There is no interrupt pending */ + return IRQ_HANDLED; + } + if (mcp_read(mcp, MCP_INTCAP, &intcap)) goto unlock; @@ -368,11 +373,6 @@ static irqreturn_t mcp23s08_irq(int irq, void *data) mcp->cached_gpio = gpio; mutex_unlock(&mcp->lock); - if (intf == 0) { - /* There is no interrupt pending */ - return IRQ_HANDLED; - } - dev_dbg(mcp->chip.parent, "intcap 0x%04X intf 0x%04X gpio_orig 0x%04X gpio 0x%04X\n", intcap, intf, gpio_orig, gpio); -- 2.30.2
