[PATCH v4 2/5] i2c:ocores: do not handle IRQ if IF is not set

Federico Vaga
2019-02-11T08:31:19Z

If the Interrupt Flag (IF) is not set, we should not handle the IRQ:
- the line can be shared with other devices
- it can be a spurious interrupt

To avoid reading twice the status register, the ocores_process() function
expects it to be read by the caller.

Signed-off-by: Federico Vaga <federico.vaga@cern.ch>
Acked-by: Peter Korsgaard <peter@korsgaard.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>

---
drivers/i2c/busses/i2c-ocores.c | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/i2c/busses/i2c-ocores.c b/drivers/i2c/busses/i2c-ocores.c
index aa85202..fcc2558 100644
--- a/drivers/i2c/busses/i2c-ocores.c
+++ b/drivers/i2c/busses/i2c-ocores.c
@@ -143,10 +143,9 @@ static inline u8 oc_getreg(struct ocores_i2c *i2c, int reg)
return i2c->getreg(i2c, reg);
}

-static void ocores_process(struct ocores_i2c *i2c)
+static void ocores_process(struct ocores_i2c *i2c, u8 stat)
{
struct i2c_msg *msg = i2c->msg;
- u8 stat = oc_getreg(i2c, OCI2C_STATUS);
unsigned long flags;

/*
@@ -223,8 +222,12 @@ out:
static irqreturn_t ocores_isr(int irq, void *dev_id)
{
struct ocores_i2c *i2c = dev_id;
+ u8 stat = oc_getreg(i2c, OCI2C_STATUS);
+
+ if (!(stat & OCI2C_STAT_IF))
+ return IRQ_NONE;

- ocores_process(i2c);
+ ocores_process(i2c, stat);

return IRQ_HANDLED;
}
--
2.15.0