i2c: xiic: Only ever transfer single message

Transferring multiple messages via XIIC suffers from strange interaction
between the interrupt status/enable register flags. These flags are being
reused in the hardware to indicate different things for read and write
transfer, and doing multiple transactions becomes horribly complex. Just
send a single transaction and reload the controller with another message
once the transaction is done in the interrupt handler thread.

Signed-off-by: Marek Vasut <marex@denx.de>
Acked-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Wolfram Sang <wsa@kernel.org>

diff --git a/drivers/i2c/busses/i2c-xiic.c b/drivers/i2c/busses/i2c-xiic.c
index f7277629923ff5c45873184a14558f147d274394..6cd7830fe4898974918cb29d75ddc9ff28857c28 100644 (file)
--- a/drivers/i2c/busses/i2c-xiic.c
+++ b/drivers/i2c/busses/i2c-xiic.c
@@ -609,8 +609,6 @@ static void xiic_start_send(struct xiic_i2c *i2c)
 {
        struct i2c_msg *msg = i2c->tx_msg;
 
-       xiic_irq_clr(i2c, XIIC_INTR_TX_ERROR_MASK);
-
        dev_dbg(i2c->adap.dev.parent, "%s entry, msg: %p, len: %d",
                __func__, msg, msg->len);
        dev_dbg(i2c->adap.dev.parent, "%s entry, ISR: 0x%x, CR: 0x%x\n",
@@ -628,16 +626,17 @@ static void xiic_start_send(struct xiic_i2c *i2c)
                xiic_setreg16(i2c, XIIC_DTR_REG_OFFSET, data);
        }
 
-       xiic_fill_tx_fifo(i2c);
-
        /* Clear any pending Tx empty, Tx Error and then enable them. */
        xiic_irq_clr_en(i2c, XIIC_INTR_TX_EMPTY_MASK | XIIC_INTR_TX_ERROR_MASK |
-               XIIC_INTR_BNB_MASK);
+               XIIC_INTR_BNB_MASK |
+               ((i2c->nmsgs > 1 || xiic_tx_space(i2c)) ?
+                       XIIC_INTR_TX_HALF_MASK : 0));
+
+       xiic_fill_tx_fifo(i2c);
 }
 
 static void __xiic_start_xfer(struct xiic_i2c *i2c)
 {
-       int first = 1;
        int fifo_space = xiic_tx_fifo_space(i2c);
        dev_dbg(i2c->adap.dev.parent, "%s entry, msg: %p, fifos space: %d\n",
                __func__, i2c->tx_msg, fifo_space);
@@ -648,35 +647,12 @@ static void __xiic_start_xfer(struct xiic_i2c *i2c)
        i2c->rx_pos = 0;
        i2c->tx_pos = 0;
        i2c->state = STATE_START;
-       while ((fifo_space >= 2) && (first || (i2c->nmsgs > 1))) {
-               if (!first) {
-                       i2c->nmsgs--;
-                       i2c->tx_msg++;
-                       i2c->tx_pos = 0;
-               } else
-                       first = 0;
-
-               if (i2c->tx_msg->flags & I2C_M_RD) {
-                       /* we dont date putting several reads in the FIFO */
-                       xiic_start_recv(i2c);
-                       return;
-               } else {
-                       xiic_start_send(i2c);
-                       if (xiic_tx_space(i2c) != 0) {
-                               /* the message could not be completely sent */
-                               break;
-                       }
-               }
-
-               fifo_space = xiic_tx_fifo_space(i2c);
+       if (i2c->tx_msg->flags & I2C_M_RD) {
+               /* we dont date putting several reads in the FIFO */
+               xiic_start_recv(i2c);
+       } else {
+               xiic_start_send(i2c);
        }
-
-       /* there are more messages or the current one could not be completely
-        * put into the FIFO, also enable the half empty interrupt
-        */
-       if (i2c->nmsgs > 1 || xiic_tx_space(i2c))
-               xiic_irq_clr_en(i2c, XIIC_INTR_TX_HALF_MASK);
-
 }
 
 static int xiic_start_xfer(struct xiic_i2c *i2c, struct i2c_msg *msgs, int num)