[src/trunk]: src/sys/dev/ic ahci_intr: use ffs in the port bitmask instead of...

[jmcneill <jmcneill%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/8fefe4a75de4
branches:  trunk
changeset: 979366:8fefe4a75de4
user:      jmcneill <jmcneill%NetBSD.org@localhost>
date:      Sat Dec 26 15:40:29 2020 +0000

description:
ahci_intr: use ffs in the port bitmask instead of looping over all 32 bits

diffstat:

 sys/dev/ic/ahcisata_core.c |  17 ++++++++++-------
 1 files changed, 10 insertions(+), 7 deletions(-)

diffs (44 lines):

diff -r baba13c42c3f -r 8fefe4a75de4 sys/dev/ic/ahcisata_core.c
--- a/sys/dev/ic/ahcisata_core.c        Sat Dec 26 15:28:52 2020 +0000
+++ b/sys/dev/ic/ahcisata_core.c        Sat Dec 26 15:40:29 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: ahcisata_core.c,v 1.88 2020/12/26 10:56:25 jmcneill Exp $      */
+/*     $NetBSD: ahcisata_core.c,v 1.89 2020/12/26 15:40:29 jmcneill Exp $      */
 
 /*
  * Copyright (c) 2006 Manuel Bouyer.
@@ -26,7 +26,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: ahcisata_core.c,v 1.88 2020/12/26 10:56:25 jmcneill Exp $");
+__KERNEL_RCSID(0, "$NetBSD: ahcisata_core.c,v 1.89 2020/12/26 15:40:29 jmcneill Exp $");
 
 #include <sys/types.h>
 #include <sys/malloc.h>
@@ -592,17 +592,20 @@
 ahci_intr(void *v)
 {
        struct ahci_softc *sc = v;
-       uint32_t is;
-       int i, r = 0;
+       uint32_t is, ports;
+       int bit, r = 0;
 
        while ((is = AHCI_READ(sc, AHCI_IS))) {
                AHCIDEBUG_PRINT(("%s ahci_intr 0x%x\n", AHCINAME(sc), is),
                    DEBUG_INTR);
                r = 1;
                AHCI_WRITE(sc, AHCI_IS, is);
-               for (i = 0; i < AHCI_MAX_PORTS; i++)
-                       if (is & (1U << i))
-                               ahci_intr_port(&sc->sc_channels[i]);
+               ports = is;
+               while ((bit = ffs(ports)) != 0) {
+                       bit--;
+                       ahci_intr_port(&sc->sc_channels[bit]);
+                       ports &= ~(1U << bit);
+               }
        }
 
        return r;