acpivout: try to consistently adjust brightness by 5%

[joshua stein]

When responding to hardware keys to increment or decrement screen 
brightness, don't just adjust by 1 BCL level as there may be 100 
levels.  Find the next brightness level that is at least 5% up or 
down, and use that.


Index: dev/acpi/acpivout.c
===================================================================
RCS file: /cvs/src/sys/dev/acpi/acpivout.c,v
retrieving revision 1.13
diff -u -p -u -p -r1.13 acpivout.c
--- dev/acpi/acpivout.c 13 Oct 2019 10:56:31 -0000      1.13
+++ dev/acpi/acpivout.c 14 Oct 2019 02:26:12 -0000
@@ -47,6 +47,8 @@ int   acpivout_notify(struct aml_node *, i
 #define NOTIFY_BRIGHTNESS_ZERO         0x88
 #define NOTIFY_DISPLAY_OFF             0x89
 
+#define BRIGHTNESS_STEP                        5
+
 struct acpivout_softc {
        struct device           sc_dev;
 
@@ -61,8 +63,7 @@ struct acpivout_softc {
 };
 
 void   acpivout_brightness_cycle(struct acpivout_softc *);
-void   acpivout_brightness_up(struct acpivout_softc *);
-void   acpivout_brightness_down(struct acpivout_softc *);
+void   acpivout_brightness_step(struct acpivout_softc *, int);
 void   acpivout_brightness_zero(struct acpivout_softc *);
 int    acpivout_get_brightness(struct acpivout_softc *);
 int    acpivout_find_brightness(struct acpivout_softc *, int);
@@ -128,10 +129,10 @@ acpivout_notify(struct aml_node *node, i
                acpivout_brightness_cycle(sc);
                break;
        case NOTIFY_BRIGHTNESS_UP:
-               acpivout_brightness_up(sc);
+               acpivout_brightness_step(sc, 1);
                break;
        case NOTIFY_BRIGHTNESS_DOWN:
-               acpivout_brightness_down(sc);
+               acpivout_brightness_step(sc, -1);
                break;
        case NOTIFY_BRIGHTNESS_ZERO:
                acpivout_brightness_zero(sc);
@@ -158,45 +159,31 @@ acpivout_brightness_cycle(struct acpivou
        if (cur_level == sc->sc_bcl[sc->sc_bcl_len - 1])
                acpivout_brightness_zero(sc);
        else
-               acpivout_brightness_up(sc);
-}
-
-void
-acpivout_brightness_up(struct acpivout_softc *sc)
-{
-       int i, cur_level;
-
-       if (sc->sc_bcl_len == 0)
-               return;
-       cur_level = acpivout_get_brightness(sc);
-       if (cur_level == -1)
-               return;
-
-       /* check for max brightness level */
-       if (cur_level == sc->sc_bcl[sc->sc_bcl_len - 1])
-               return;
-
-       for (i = 0; i < sc->sc_bcl_len && cur_level != sc->sc_bcl[i]; i++);
-       acpivout_set_brightness(sc, sc->sc_bcl[i + 1]);
+               acpivout_brightness_step(sc, 1);
 }
 
 void
-acpivout_brightness_down(struct acpivout_softc *sc)
+acpivout_brightness_step(struct acpivout_softc *sc, int dir)
 {
-       int i, cur_level;
+       int level, nlevel;
 
        if (sc->sc_bcl_len == 0)
                return;
-       cur_level = acpivout_get_brightness(sc);
-       if (cur_level == -1)
+       level = acpivout_get_brightness(sc);
+       if (level == -1)
                return;
 
-       /* check for min brightness level */
-       if (cur_level == sc->sc_bcl[0])
+       nlevel = acpivout_find_brightness(sc, level + (dir * BRIGHTNESS_STEP));
+       if (nlevel == level) {
+               if (dir == 1 && (nlevel + 1 < sc->sc_bcl_len))
+                       nlevel++;
+               else if (dir == -1 && (nlevel - 1 >= 0))
+                       nlevel--;
+       }
+       if (nlevel == level)
                return;
 
-       for (i = 0; i < sc->sc_bcl_len && cur_level != sc->sc_bcl[i]; i++);
-       acpivout_set_brightness(sc, sc->sc_bcl[i - 1]);
+       acpivout_set_brightness(sc, nlevel);
 }
 
 void