i2c: at91: disable TXRDY interrupt after sending data

commit d12e3aae160fb26b534c4496b211d6e60a5179ed upstream.

Driver was not disabling TXRDY interrupt after last TX byte.
This caused interrupt storm until transfer timeouts for slow
or broken device on the bus. The patch fixes the interrupt storm
on my SAMA5D2-based board.

Cc: stable@vger.kernel.org # 5.2.x
[v5.2 introduced file split; the patch should apply to i2c-at91.c before the split]
Fixes: fac368a04048 ("i2c: at91: add new driver")
Signed-off-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Acked-by: Ludovic Desroches <ludovic.desroches@microchip.com>
Tested-by: Raag Jadav <raagjadav@gmail.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/i2c/busses/i2c-at91-master.c b/drivers/i2c/busses/i2c-at91-master.c
index e87232f2e70855c3c5a21b1028597b8fd298a114..a3fcc35ffd3b65b037965efb5ededd808b82ea8b 100644 (file)
--- a/drivers/i2c/busses/i2c-at91-master.c
+++ b/drivers/i2c/busses/i2c-at91-master.c
@@ -122,9 +122,11 @@ static void at91_twi_write_next_byte(struct at91_twi_dev *dev)
        writeb_relaxed(*dev->buf, dev->base + AT91_TWI_THR);
 
        /* send stop when last byte has been written */
-       if (--dev->buf_len == 0)
+       if (--dev->buf_len == 0) {
                if (!dev->use_alt_cmd)
                        at91_twi_write(dev, AT91_TWI_CR, AT91_TWI_STOP);
+               at91_twi_write(dev, AT91_TWI_IDR, AT91_TWI_TXRDY);
+       }
 
        dev_dbg(dev->dev, "wrote 0x%x, to go %zu\n", *dev->buf, dev->buf_len);
 
@@ -542,9 +544,8 @@ static int at91_do_twi_transfer(struct at91_twi_dev *dev)
                } else {
                        at91_twi_write_next_byte(dev);
                        at91_twi_write(dev, AT91_TWI_IER,
-                                      AT91_TWI_TXCOMP |
-                                      AT91_TWI_NACK |
-                                      AT91_TWI_TXRDY);
+                                      AT91_TWI_TXCOMP | AT91_TWI_NACK |
+                                      (dev->buf_len ? AT91_TWI_TXRDY : 0));
                }
        }