Hi Alexander,
On 13/05/2019 15:59, Alexander Stein wrote:
Am Montag, 13. Mai 2019, 16:02:18 CEST schrieb Joe Burmeister:
Hi Alexander,
You probably noticed there is a v3, but that just adds the missing signoff.
On 13/05/2019 13:59, Alexander Stein wrote:
Am Montag, 13. Mai 2019, 14:00:24 CEST schrieb Joe Burmeister:
Though it has a 'standby' it doesn't appear to be an issue and
marking the chip with can_sleep means gpiolib.c won't allow its use
as a interrupt controller.
---
drivers/pinctrl/pinctrl-mcp23s08.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/drivers/pinctrl/pinctrl-mcp23s08.c b/drivers/pinctrl/
pinctrl-mcp23s08.c
index 3fc63cb5b332..7334d8eb9135 100644
--- a/drivers/pinctrl/pinctrl-mcp23s08.c
+++ b/drivers/pinctrl/pinctrl-mcp23s08.c
@@ -890,7 +890,7 @@ static int mcp23s08_probe_one(struct mcp23s08 *mcp,
struct device *dev,
return PTR_ERR(mcp->regmap);
mcp->chip.base = base;
- mcp->chip.can_sleep = true;
+ mcp->chip.can_sleep = false;
mcp->chip.parent = dev;
mcp->chip.owner = THIS_MODULE;
IMHO this is completly wrong, please refer to the documentation of this
flag, e.g. https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/
tree/include/linux/gpio/driver.h#n217
It essentially means you can't use this GPIOs from atomic context, as SPI
or I2C transfers block/sleep, hence the name.
In your case the IRQs are probably not requested as threaded, as stated in
the link above.
I should have seen that bit of docs, sorry.
That opens a bit of a Pandora's box.
Now I look again with a better idea of what that means, I see this isn't
the only driver that has a mutex, and sets can_sleep to true, uses
devm_request_threaded_irq, and called
gpiochip_set_nested_irqchip/gpiochip_set_chained_irqchip.
Now I'm confused because I can't see how you can use them as nested
interrupt controllers.
They will all cause "you cannot have chained interrupts on a chip that
may sleep" from gpiochip_set_cascaded_irqchip the moment you try.
I'm still reading through what I do now, but any hints or tips would be
appreciated.
Have a look at https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/
linux.git/tree/Documentation/driver-api/gpio/driver.rst#n309 which pretty much
describes the types.
Was just reading
https://www.kernel.org/doc/Documentation/gpio/driver.txt as this came
through.
I think you are confusing chained and nested IRQ controllers. Using
gpiochip_set_nested_irqchip cannot result in that error.
mcp23s08 driver is using gpiochip_set_nested_irqchip appropriately.
It was seeing the error was what I thought brought me to can_sleep.
I assumed about can_sleep and assumed completely wrong.
I've just removed this second patch and it all seams to still be working
fine.
Ignore this second patch, it's clearly nonsense. Sorry I wasted your
time, if it's any consolation, I wasted much more of mine.
Should I resubmit the series with just the first patch?
I'm wondering what you are trying to resolve. Are you attaching another IRQ
controller to MCP23Sxx inputs?
We are using a MCP23S017 in a Raspberry Pi Compute Module motherboard, 4
interrupt lines go into it and 2 come out.
(Though it turns out might as well be 1 as they both go into the same
GPIO bank on the Pi, so same interrupt regardless.)
Best regards,
Alexander
Regards,
Joe
