2019-08-07 07:20:28

by Fuqian Huang

[permalink] [raw]

Subject: [PATCH v2] i2c: avoid sleep in IRQ context

---

i2c_pxa_handler -> i2c_pxa_irq_txempty ->
i2c_pxa_reset -> i2c_pxa_set_slave -> i2c_pxa_wait_slave

As i2c_pxa_handler is an interrupt handler, it will finally
calls i2c_pxa_wait_slave which calls msleep.

Add in_interrupt check before msleep to avoid sleep
in IRQ context.
When in interrupt context, use mdelay instead of msleep.

Signed-off-by: Fuqian Huang <[email protected]>
---
drivers/i2c/busses/i2c-pxa.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/i2c/busses/i2c-pxa.c b/drivers/i2c/busses/i2c-pxa.c
index 2c3c3d6935c0..876e693bafd9 100644
--- a/drivers/i2c/busses/i2c-pxa.c
+++ b/drivers/i2c/busses/i2c-pxa.c
@@ -456,7 +456,10 @@ static int i2c_pxa_wait_slave(struct pxa_i2c *i2c)
return 1;
}

- msleep(1);
+ if (in_interrupt())
+ mdelay(1);
+ else
+ msleep(1);
}

if (i2c_debug > 0)
--
2.11.0

2019-08-14 10:09:08

by Wolfram Sang

[permalink] [raw]

Subject: Re: [PATCH v2] i2c: avoid sleep in IRQ context

---

On Wed, Aug 07, 2019 at 03:18:07PM +0800, Fuqian Huang wrote:
> i2c_pxa_handler -> i2c_pxa_irq_txempty ->
> i2c_pxa_reset -> i2c_pxa_set_slave -> i2c_pxa_wait_slave
>
> As i2c_pxa_handler is an interrupt handler, it will finally
> calls i2c_pxa_wait_slave which calls msleep.
>
> Add in_interrupt check before msleep to avoid sleep
> in IRQ context.
> When in interrupt context, use mdelay instead of msleep.
>
> Signed-off-by: Fuqian Huang <[email protected]>

Adding RMK to CC because he is the PXA I2C slave user I know of.

> ---
> drivers/i2c/busses/i2c-pxa.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/i2c/busses/i2c-pxa.c b/drivers/i2c/busses/i2c-pxa.c
> index 2c3c3d6935c0..876e693bafd9 100644
> --- a/drivers/i2c/busses/i2c-pxa.c
> +++ b/drivers/i2c/busses/i2c-pxa.c
> @@ -456,7 +456,10 @@ static int i2c_pxa_wait_slave(struct pxa_i2c *i2c)
> return 1;
> }
>
> - msleep(1);
> + if (in_interrupt())
> + mdelay(1);
> + else
> + msleep(1);
> }
>
> if (i2c_debug > 0)
> --
> 2.11.0
>

---

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