[PATCH v2 5/9] i2c: designware: Do not enable interrupts shortly in polling mode

Jarkko Nikula
2024-02-06T14:52:23Z

I was testing the polling mode txgbe_i2c_dw_xfer_quirk() on a HW where
the i2c-designware has interrupt connected and shared with other device.
I noticed there is a bogus interrupt for each transfer.

Reason for this that both polling mode functions call the
i2c_dw_xfer_init() which enable interrupts then followed by immediate
disable by the same polling mode functions. This is enough to trigger
TX_EMPTY interrupt.

Fix this by introducing a __i2c_dw_write_intr_mask() helper that unmasks
interrupts conditionally and use it in i2c_dw_xfer_init().

Signed-off-by: Jarkko Nikula <jarkko.nikula@linux.intel.com>
---
drivers/i2c/busses/i2c-designware-core.h | 8 ++++++++
drivers/i2c/busses/i2c-designware-master.c | 4 +---
2 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/drivers/i2c/busses/i2c-designware-core.h b/drivers/i2c/busses/i2c-designware-core.h
index ee93c0b4e817..353d753d9d5d 100644
--- a/drivers/i2c/busses/i2c-designware-core.h
+++ b/drivers/i2c/busses/i2c-designware-core.h
@@ -353,6 +353,14 @@ static inline void __i2c_dw_disable_nowait(struct dw_i2c_dev *dev)
dev->status &= ~STATUS_ACTIVE;
}

+static inline void __i2c_dw_write_intr_mask(struct dw_i2c_dev *dev,
+ unsigned int intr_mask)
+{
+ unsigned int val = dev->flags & ACCESS_POLLING ? 0 : intr_mask;
+
+ regmap_write(dev->map, DW_IC_INTR_MASK, val);
+}
+
void __i2c_dw_disable(struct dw_i2c_dev *dev);

extern void i2c_dw_configure_master(struct dw_i2c_dev *dev);
diff --git a/drivers/i2c/busses/i2c-designware-master.c b/drivers/i2c/busses/i2c-designware-master.c
index e879a0f5cc97..835d82e2c5fe 100644
--- a/drivers/i2c/busses/i2c-designware-master.c
+++ b/drivers/i2c/busses/i2c-designware-master.c
@@ -250,7 +250,7 @@ static void i2c_dw_xfer_init(struct dw_i2c_dev *dev)

/* Clear and enable interrupts */
regmap_read(dev->map, DW_IC_CLR_INTR, &dummy);
- regmap_write(dev->map, DW_IC_INTR_MASK, DW_IC_INTR_MASTER_MASK);
+ __i2c_dw_write_intr_mask(dev, DW_IC_INTR_MASTER_MASK);
}

static int i2c_dw_check_stopbit(struct dw_i2c_dev *dev)
@@ -300,7 +300,6 @@ static int amd_i2c_dw_xfer_quirk(struct i2c_adapter *adap, struct i2c_msg *msgs,
dev->msgs = msgs;
dev->msgs_num = num_msgs;
i2c_dw_xfer_init(dev);
- regmap_write(dev->map, DW_IC_INTR_MASK, 0);

/* Initiate messages read/write transaction */
for (msg_wrt_idx = 0; msg_wrt_idx < num_msgs; msg_wrt_idx++) {
@@ -384,7 +383,6 @@ static int txgbe_i2c_dw_xfer_quirk(struct i2c_adapter *adap, struct i2c_msg *msg
dev->msgs = msgs;
dev->msgs_num = num_msgs;
i2c_dw_xfer_init(dev);
- regmap_write(dev->map, DW_IC_INTR_MASK, 0);

for (msg_idx = 0; msg_idx < num_msgs; msg_idx++) {
buf = msgs[msg_idx].buf;
--
2.43.0