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| author | Radim Pavlik <radim.pavlik@tbs-biometrics.com> | 2021-06-01 10:48:18 +0000 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-07-19 08:53:09 +0200 |
| commit | c0b70153f13e0d8b8637ce59fa12f576242efe15 (patch) | |
| tree | 20a56b7c1a2326c8ab9d995c6ef6d28f602011aa /drivers/pinctrl | |
| parent | e10062afd67d993f7eb28d34a4a4e56ae1ff0091 (diff) | |
| download | linux-c0b70153f13e0d8b8637ce59fa12f576242efe15.tar.gz linux-c0b70153f13e0d8b8637ce59fa12f576242efe15.tar.bz2 linux-c0b70153f13e0d8b8637ce59fa12f576242efe15.zip | |
pinctrl: mcp23s08: fix race condition in irq handler
[ 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@tbs-biometrics.com>
Link: https://lore.kernel.org/r/AM7PR06MB6769E1183F68DEBB252F665ABA3E9@AM7PR06MB6769.eurprd06.prod.outlook.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Diffstat (limited to 'drivers/pinctrl')
| -rw-r--r-- | drivers/pinctrl/pinctrl-mcp23s08.c | 10 |
1 files changed, 5 insertions, 5 deletions
diff --git a/drivers/pinctrl/pinctrl-mcp23s08.c b/drivers/pinctrl/pinctrl-mcp23s08.c index d8bcbefcba89..9d5e2d9b6b93 100644 --- a/drivers/pinctrl/pinctrl-mcp23s08.c +++ b/drivers/pinctrl/pinctrl-mcp23s08.c @@ -459,6 +459,11 @@ 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; @@ -476,11 +481,6 @@ 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); |