serial: sc16is7xx: remove obsolete loop in sc16is7xx_port_irq()

commit ed647256e8f226241ecff7baaecdb8632ffc7ec1 upstream.

Commit 834449872105 ("sc16is7xx: Fix for multi-channel stall") changed
sc16is7xx_port_irq() from looping multiple times when there was still
interrupts to serve. It simply changed the do {} while(1) loop to a
do {} while(0) loop, which makes the loop itself now obsolete.

Clean the code by removing this obsolete do {} while(0) loop.

Fixes: 834449872105 ("sc16is7xx: Fix for multi-channel stall")
Cc:  <stable@vger.kernel.org>
Suggested-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Hugo Villeneuve <hvilleneuve@dimonoff.com>
Link: https://lore.kernel.org/r/20231221231823.2327894-5-hugo@hugovil.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c
index 06f9f33..910870c 100644 (file)
--- a/drivers/tty/serial/sc16is7xx.c
+++ b/drivers/tty/serial/sc16is7xx.c
@@ -724,58 +724,55 @@ static void sc16is7xx_update_mlines(struct sc16is7xx_one *one)
 static bool sc16is7xx_port_irq(struct sc16is7xx_port *s, int portno)
 {
        bool rc = true;
+       unsigned int iir, rxlen;
        struct uart_port *port = &s->p[portno].port;
        struct sc16is7xx_one *one = to_sc16is7xx_one(port, port);
 
        mutex_lock(&one->efr_lock);
 
-       do {
-               unsigned int iir, rxlen;
+       iir = sc16is7xx_port_read(port, SC16IS7XX_IIR_REG);
+       if (iir & SC16IS7XX_IIR_NO_INT_BIT) {
+               rc = false;
+               goto out_port_irq;
+       }
 
-               iir = sc16is7xx_port_read(port, SC16IS7XX_IIR_REG);
-               if (iir & SC16IS7XX_IIR_NO_INT_BIT) {
-                       rc = false;
-                       goto out_port_irq;
-               }
+       iir &= SC16IS7XX_IIR_ID_MASK;
 
-               iir &= SC16IS7XX_IIR_ID_MASK;
-
-               switch (iir) {
-               case SC16IS7XX_IIR_RDI_SRC:
-               case SC16IS7XX_IIR_RLSE_SRC:
-               case SC16IS7XX_IIR_RTOI_SRC:
-               case SC16IS7XX_IIR_XOFFI_SRC:
-                       rxlen = sc16is7xx_port_read(port, SC16IS7XX_RXLVL_REG);
-
-                       /*
-                        * There is a silicon bug that makes the chip report a
-                        * time-out interrupt but no data in the FIFO. This is
-                        * described in errata section 18.1.4.
-                        *
-                        * When this happens, read one byte from the FIFO to
-                        * clear the interrupt.
-                        */
-                       if (iir == SC16IS7XX_IIR_RTOI_SRC && !rxlen)
-                               rxlen = 1;
-
-                       if (rxlen)
-                               sc16is7xx_handle_rx(port, rxlen, iir);
-                       break;
+       switch (iir) {
+       case SC16IS7XX_IIR_RDI_SRC:
+       case SC16IS7XX_IIR_RLSE_SRC:
+       case SC16IS7XX_IIR_RTOI_SRC:
+       case SC16IS7XX_IIR_XOFFI_SRC:
+               rxlen = sc16is7xx_port_read(port, SC16IS7XX_RXLVL_REG);
+
+               /*
+                * There is a silicon bug that makes the chip report a
+                * time-out interrupt but no data in the FIFO. This is
+                * described in errata section 18.1.4.
+                *
+                * When this happens, read one byte from the FIFO to
+                * clear the interrupt.
+                */
+               if (iir == SC16IS7XX_IIR_RTOI_SRC && !rxlen)
+                       rxlen = 1;
+
+               if (rxlen)
+                       sc16is7xx_handle_rx(port, rxlen, iir);
+               break;
                /* CTSRTS interrupt comes only when CTS goes inactive */
-               case SC16IS7XX_IIR_CTSRTS_SRC:
-               case SC16IS7XX_IIR_MSI_SRC:
-                       sc16is7xx_update_mlines(one);
-                       break;
-               case SC16IS7XX_IIR_THRI_SRC:
-                       sc16is7xx_handle_tx(port);
-                       break;
-               default:
-                       dev_err_ratelimited(port->dev,
-                                           "ttySC%i: Unexpected interrupt: %x",
-                                           port->line, iir);
-                       break;
-               }
-       } while (0);
+       case SC16IS7XX_IIR_CTSRTS_SRC:
+       case SC16IS7XX_IIR_MSI_SRC:
+               sc16is7xx_update_mlines(one);
+               break;
+       case SC16IS7XX_IIR_THRI_SRC:
+               sc16is7xx_handle_tx(port);
+               break;
+       default:
+               dev_err_ratelimited(port->dev,
+                                   "ttySC%i: Unexpected interrupt: %x",
+                                   port->line, iir);
+               break;
+       }
 
 out_port_irq:
        mutex_unlock(&one->efr_lock);