[PATCH 4/4] i2c: xiic: Fix Tx Interrupt path for grouped messages

Shubhrajyoti Datta
2022-04-20T08:01:09Z

From: Raviteja Narayanam <raviteja.narayanam@xilinx.com>

When a group of messages are sent from user space as a set, if
the last message has less than Tx FIFO DEPTH number of bytes
to transfer, Tx half empty interrupt is triggered continuously
from the hardware. It is due to Bus not busy interrupt coming
along with Tx half empty and tx empty.

Hence, service the Tx interrupts before Bus not busy interrupt
to update the i2c message status correctly.

Signed-off-by: Raviteja Narayanam <raviteja.narayanam@xilinx.com>
Signed-off-by: Shubhrajyoti Datta <shubhrajyoti.datta@xilinx.com>
---
drivers/i2c/busses/i2c-xiic.c | 38 ++++++++++++++++++-----------------
1 file changed, 20 insertions(+), 18 deletions(-)

diff --git a/drivers/i2c/busses/i2c-xiic.c b/drivers/i2c/busses/i2c-xiic.c
index eb4d34e7c0fe..953f7cffe0d8 100644
--- a/drivers/i2c/busses/i2c-xiic.c
+++ b/drivers/i2c/busses/i2c-xiic.c
@@ -468,24 +468,6 @@ static irqreturn_t xiic_process(int irq, void *dev_id)
}
}
}
- if (pend & XIIC_INTR_BNB_MASK) {
- /* IIC bus has transitioned to not busy */
- clr |= XIIC_INTR_BNB_MASK;
-
- /* The bus is not busy, disable BusNotBusy interrupt */
- xiic_irq_dis(i2c, XIIC_INTR_BNB_MASK);
-
- if (!i2c->tx_msg)
- goto out;
-
- wakeup_req = 1;
-
- if (i2c->nmsgs == 1 && !i2c->rx_msg &&
- xiic_tx_space(i2c) == 0)
- wakeup_code = STATE_DONE;
- else
- wakeup_code = STATE_ERROR;
- }
if (pend & (XIIC_INTR_TX_EMPTY_MASK | XIIC_INTR_TX_HALF_MASK)) {
/* Transmit register/FIFO is empty or ½ empty */

@@ -522,6 +504,26 @@ static irqreturn_t xiic_process(int irq, void *dev_id)
*/
xiic_irq_dis(i2c, XIIC_INTR_TX_HALF_MASK);
}
+
+ if (pend & XIIC_INTR_BNB_MASK) {
+ /* IIC bus has transitioned to not busy */
+ clr |= XIIC_INTR_BNB_MASK;
+
+ /* The bus is not busy, disable BusNotBusy interrupt */
+ xiic_irq_dis(i2c, XIIC_INTR_BNB_MASK);
+
+ if (!i2c->tx_msg)
+ goto out;
+
+ wakeup_req = 1;
+
+ if (i2c->nmsgs == 1 && !i2c->rx_msg &&
+ xiic_tx_space(i2c) == 0)
+ wakeup_code = STATE_DONE;
+ else
+ wakeup_code = STATE_ERROR;
+ }
+
out:
dev_dbg(i2c->adap.dev.parent, "%s clr: 0x%x\n", __func__, clr);

--
2.17.1