char: make some qemu_chr_fe skip if no driver

In most cases, front ends do not care about the side effect of
CharBackend, so we can simply skip the checks and call the qemu_chr_fe
functions even without associated CharDriver.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20161022095318.17775-20-marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 9 insertions, 17 deletions

diff --git a/hw/char/imx_serial.c b/hw/char/imx_serial.c
index d9a0a25d44..8dbb7b26e6 100644
--- a/hw/char/imx_serial.c
+++ b/hw/char/imx_serial.c
@@ -121,9 +121,7 @@ static uint64_t imx_serial_read(void *opaque, hwaddr offset,
             s->usr2 &= ~USR2_RDR;
             s->uts1 |= UTS1_RXEMPTY;
             imx_update(s);
-            if (s->chr.chr) {
-                qemu_chr_fe_accept_input(&s->chr);
-            }
+            qemu_chr_fe_accept_input(&s->chr);
         }
         return c;
 
@@ -182,11 +180,9 @@ static void imx_serial_write(void *opaque, hwaddr offset,
     case 0x10: /* UTXD */
         ch = value;
         if (s->ucr2 & UCR2_TXEN) {
-            if (s->chr.chr) {
-                /* XXX this blocks entire thread. Rewrite to use
-                 * qemu_chr_fe_write and background I/O callbacks */
-                qemu_chr_fe_write_all(&s->chr, &ch, 1);
-            }
+            /* XXX this blocks entire thread. Rewrite to use
+             * qemu_chr_fe_write and background I/O callbacks */
+            qemu_chr_fe_write_all(&s->chr, &ch, 1);
             s->usr1 &= ~USR1_TRDY;
             imx_update(s);
             s->usr1 |= USR1_TRDY;
@@ -215,9 +211,7 @@ static void imx_serial_write(void *opaque, hwaddr offset,
         }
         if (value & UCR2_RXEN) {
             if (!(s->ucr2 & UCR2_RXEN)) {
-                if (s->chr.chr) {
-                    qemu_chr_fe_accept_input(&s->chr);
-                }
+                qemu_chr_fe_accept_input(&s->chr);
             }
         }
         s->ucr2 = value & 0xffff;
@@ -319,12 +313,10 @@ static void imx_serial_realize(DeviceState *dev, Error **errp)
 {
     IMXSerialState *s = IMX_SERIAL(dev);
 
-    if (s->chr.chr) {
-        qemu_chr_fe_set_handlers(&s->chr, imx_can_receive, imx_receive,
-                                 imx_event, s, NULL);
-    } else {
-        DPRINTF("No char dev for uart\n");
-    }
+    DPRINTF("char dev for uart: %p\n", qemu_chr_fe_get_driver(&s->chr));
+
+    qemu_chr_fe_set_handlers(&s->chr, imx_can_receive, imx_receive,
+                             imx_event, s, NULL);
 }
 
 static void imx_serial_init(Object *obj)