i2c: img-scb: Clear line and interrupt status before starting a transfer

Clear line status and all generated interrupts from the interrupt
status register before starting a transfer, as we may have
unserviced interrupts from previous transfers that might be
handled in the context of the new transfer.

Fixes: commit 27bce457d588 ("i2c: img-scb: Add Imagination Technologies I2C SCB driver")
Signed-off-by: Sifan Naeem <sifan.naeem@imgtec.com>
Acked-by: James Hogan <james.hogan@imgtec.com>
Reviewed-by: James Hartley <james.hartley@imgtec.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

diff --git a/drivers/i2c/busses/i2c-img-scb.c b/drivers/i2c/busses/i2c-img-scb.c
index 049d193..0fa4715 100644 (file)
--- a/drivers/i2c/busses/i2c-img-scb.c
+++ b/drivers/i2c/busses/i2c-img-scb.c
@@ -1060,6 +1060,15 @@ static int img_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
                i2c->last_msg = (i == num - 1);
                reinit_completion(&i2c->msg_complete);
 
+               /*
+                * Clear line status and all interrupts before starting a
+                * transfer, as we may have unserviced interrupts from
+                * previous transfers that might be handled in the context
+                * of the new transfer.
+                */
+               img_i2c_writel(i2c, SCB_INT_CLEAR_REG, ~0);
+               img_i2c_writel(i2c, SCB_CLEAR_REG, ~0);
+
                if (atomic)
                        img_i2c_atomic_start(i2c);
                else if (msg->flags & I2C_M_RD)