[src/trunk]: src/sys/arch/sparc/dev add counter to periodically drain the ins...

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

details:   https://anonhg.NetBSD.org/src/rev/38ce4e776d56
branches:  trunk
changeset: 376353:38ce4e776d56
user:      macallan <macallan%NetBSD.org@localhost>
date:      Tue Jun 13 10:09:31 2023 +0000

description:
add counter to periodically drain the instruction queue in order to avoid
stalling the MBus during long SX operations
adapted from xf86-video-suncg14

diffstat:

 sys/arch/sparc/dev/sx.c    |   5 +++--
 sys/arch/sparc/dev/sxvar.h |  25 ++++++++++++++++++++++++-
 2 files changed, 27 insertions(+), 3 deletions(-)

diffs (77 lines):

diff -r 0ae59b89a8ec -r 38ce4e776d56 sys/arch/sparc/dev/sx.c
--- a/sys/arch/sparc/dev/sx.c   Tue Jun 13 00:15:52 2023 +0000
+++ b/sys/arch/sparc/dev/sx.c   Tue Jun 13 10:09:31 2023 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: sx.c,v 1.6 2023/04/13 13:07:48 macallan Exp $  */
+/*     $NetBSD: sx.c,v 1.7 2023/06/13 10:09:31 macallan Exp $  */
 
 /*-
  * Copyright (c) 2013 The NetBSD Foundation, Inc.
@@ -30,7 +30,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: sx.c,v 1.6 2023/04/13 13:07:48 macallan Exp $");
+__KERNEL_RCSID(0, "$NetBSD: sx.c,v 1.7 2023/06/13 10:09:31 macallan Exp $");
 
 #include "locators.h"
 
@@ -84,6 +84,7 @@ sx_attach(device_t parent, device_t self
        sc->sc_dev = self;
        sc->sc_tag = ma->ma_bustag;
        sc->sc_uregs = ma->ma_paddr + 0x1000;
+       sc->sc_cnt = 0;
 
        if (bus_space_map(sc->sc_tag, ma->ma_paddr, 0x1000, 0, &sc->sc_regh)) {
                aprint_error_dev(self, "failed to map registers\n");
diff -r 0ae59b89a8ec -r 38ce4e776d56 sys/arch/sparc/dev/sxvar.h
--- a/sys/arch/sparc/dev/sxvar.h        Tue Jun 13 00:15:52 2023 +0000
+++ b/sys/arch/sparc/dev/sxvar.h        Tue Jun 13 10:09:31 2023 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: sxvar.h,v 1.4 2019/03/01 02:30:42 macallan Exp $       */
+/*     $NetBSD: sxvar.h,v 1.5 2023/06/13 10:09:31 macallan Exp $       */
 
 /*-
  * Copyright (c) 2013 The NetBSD Foundation, Inc.
@@ -32,11 +32,14 @@
 #ifndef SXVAR_H
 #define SXVAR_H
 
+#include <sparc/dev/sxreg.h>
+
 struct sx_softc {
        device_t                sc_dev;
        bus_addr_t              sc_uregs;
        bus_space_tag_t         sc_tag;
        bus_space_handle_t      sc_regh;
+       int                     sc_cnt;
 };
 
 static inline void
@@ -51,6 +54,26 @@ sx_read(struct sx_softc *sc, int addr)
        return bus_space_read_4(sc->sc_tag, sc->sc_regh, addr);
 }
 
+/*
+ * to be used before issuing SX instructions
+ * this will periodically allow the instruction queue to drain in order
+ * to avoid excessive MBus relinquish & retry cycles during long SX ops
+ * which may cause us to lose interrupts
+ */
+static inline void
+sx_wait(struct sx_softc *sc)
+{
+       uint32_t reg;
+       if (sc->sc_cnt > 6) {
+               do {
+                       reg = bus_space_read_4(sc->sc_tag, sc->sc_regh,
+                                                SX_CONTROL_STATUS);
+               } while ((reg & SX_MT) == 0);
+               sc->sc_cnt = 0;
+       } else
+               sc->sc_cnt++;
+}
+
 void sx_dump(void);
 
 #endif