diff options
| author |   Radim Pavlik <radim.pavlik@tbs-biometrics.com> | 2021-06-01 10:48:18 +0000 |
|---|---|---|
| committer |   Linus Walleij <linus.walleij@linaro.org> | 2021-06-07 00:23:58 +0200 |
| commit | 897120d41e7afd9da435cb00041a142aeeb53c07 (patch) | |
| tree | 05573ba7f8beb5704b3805cb5a9f8805b7d0dc23 /drivers/pinctrl | |
| parent | Merge tag 'renesas-pinctrl-for-v5.14-tag1' of git://git.kernel.org/pub/scm/linux/kernel/git/geert/renesas-drivers into devel (diff) | |
| download | linux-dev-897120d41e7afd9da435cb00041a142aeeb53c07.tar.xz linux-dev-897120d41e7afd9da435cb00041a142aeeb53c07.zip | |
pinctrl: mcp23s08: fix race condition in irq handler
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>
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 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); |